Wavetek 960 Service and user manual

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INSTRUCTION MANUAL

MODEL 960 SERIES MICRO SWEEP 1 TO 18.0 GHz MICROWAVE GENERATORS

THIS DOCUMENT CONTAINS INFORMATION PRO-PRIETARY TO WAVETEK AND IS SOLELY FOR INSTRU-MENT OPERATION AND MAINTENANCE. THE INFORMA-TION IN THIS DOCUMENT MAY NOT BE DUPLICATED IN ANY MANNER WITHOUT THE PRIOR APPROVAL IN WRITING FROM WAVETEK.

WAVETEK MICROWAVE, INC.

Code 03

488 TASMAN DRIVE, SUNNYVALE, CALIFORNIA 94089 TEL: (408) 734-5780 TWX: (910) 339-9273 TELEX: 371-6460

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WARRANTY

Wavetek warrants that all products manufactured by Wavetek conform to published Wavetek specifications and are free from defects in materials and workmanship for a period of one (1) year from the date of delivery when used under normal operating conditions and within the service conditions for which they were furnished.

The obligation of Wavetek arising from a Warranty claim shall be limited to repairing, or at its option, replacing without charge, any product which in Wavetek's sole opinion proves to be defective within the scope of the Warranty. In the event Wavetek is not able to modify, repair or replace non-conforming defective parts or components to a condition as warrantied within a reasonable time after receipt thereof, Buyers shall be credited for their value at the original purchase price.

Wavetek must be notified in writing of the defect or nonconformity within the Warranty period and the affected product returned to Wavetek's factory or to an authorized service center within (30) days after discovery of such defect or nonconformity.

For product warranties requiring return to Wavetek, products must be returned to a service facility designated by Wavetek. Buyer shall prepay shipping charges, taxes, duties and insurance for products returned to Wavetek for warranty service. Except for products returned to Buyer from another country, Wavetek shall pay for return of products to Buyer.

Wavetek shall have no responsibility hereunder for any defect or damage caused by improper storage, improper installation, unauthorized modification, misuse, neglect, inadequate maintenance, accident or for any product which has been repaired or altered by anyone other than Wavetek or its authorized representative and not in accordance with instructions furnished by Wavetek.

Exclusion of Other Warranties

The Warranty described above is Buyer's sole and exclusive remedy and no other warranty, whether written or oral, is expressed or implied. Wavetek specifically disclaims the implied warranties of merchantability and fitness for a particular purpose. No statement, representation, agreement, or understanding, oral or written, made by an agent, distributor, representative, or employee of Wavetek, which is not contained in the foregoing Warranty will be binding upon Wavetek, unless made in writing and executed by an authorized Wavetek employee. Under no circumstances shall Wavetek be liable for any direct, indirect, special, incidental, or consequential damages, expenses, losses or delays (including loss of profits) based on contract, tort, or any other legal theory.

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SECTION 1 GENERAL DESCRIPTION

4.1.2 References

4.1.3 Digital Control

4.1.4 Waveform Generator

		1-1
	1.2 SPECIFICATIONS	\|-\|
	1.2.1 Frequency Characteristics	1-1
	1.2.2 Operating modes	1 2
	1.2.3 Sweep Capability	1-2
	1.2.5 Output Characteristics	1-3
		1-0
		1-4
		1-4
	1.3 ITEMS EURNISHED	1-4
		1-4
	1.5 TEST EQUIPMENT	1-4
SECTION 2	PREPARATION FOR USE AND INSTALLATION
	2.1 MECHANICAL INSTALLATION	2-1
	2.2 ELECTRICAL INSTALLATION	2-1
	2.2.1 Power Connection	2-1
	2.2.2 Signal Connection	2-2
	2.2.3 Marker Type Selection	2-2
	2.2.4 Z-Axis Blanking Polarity Selection	2-2
	2.2.5 Tuning Filter Selection	2-3
	2.3 INITIAL CHECKOUT PROCEDURE	2-3
SECTION 3	OPERATION
	3.1 CONTROLS, CONNECTORS AND INDICATORS	3-1
	3.2 OPERATION	3-3
	3.2.1 CW Operation	3-3
	3.2.2 Start/Stop Sweep	3-4
		3-6
	3.2.4 External Triggered Sweep	3-7
	3.2.5 Frequency Markers	3-7
	3.2.6 ALC/Leveling	3-9
	3.2.7 Amplitude Modulation	3-9
	3.2.8 Frequency Modulation	3-10
	3.2.9 External Tuning	3-10
SECTION 4	CIRCUIT DESCRIPTION
	4.1 GENERAL DESCRIPTION	4-1
	4.1.1 Power Supplies	4-1

iii

4-1

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CONTENTS (Continued)

4.1.5	Frequency and Sweep Control	4-1
4.1.6	YIG Oscillator Control	4-1
4.1.7	YIG Oscillator	4-2
4.1.8	Marker Control	4-2
4.1.9	Modulation and Leveling	4-2
4.1.10	Display	4-2
4.2 D	ETAILED CIRCUIT DESCRIPTION	4-2
4.2.1	Power Supplies	4-2
4.2.2	References	4-2
4.2.3	Digital Control	4-3
4.2.4	Waveform Generator	4-5
4.2.5	Frequency and Sweep Control	4-10
4.2.6	YIG Oscillator Control	4-16
4.2.7	YIG Oscillator	4-17
4.2.8	Marker Control	4-17
4.2.9	Modulation and Leveling	4-18
4.2.10	Digital Display	4-21

SECTION 5 CALIBRATION

5.1	FACTORY REPAIR	5-1
5.2	EQUIPMENT REQUIREMENTS	5-1
5.3	PRELIMINARY SETUP PROCEDURES	5-2
51	CALIBRATION	5-3

SECTION 6 TROUBLESHOOTING

6.1 FACTORY REPAIR	6-1
6.2 BEFORE YOU START	6-1
6.3 ISOLATING A PROBLEM	6-1
6.4 BLOCK ISOLATION	6-1
6.4.1 Power Supplies	6-4
6.4.2 References	6-4
6.4.3 Frequency and Sweep Control Block	6-4
6.4.4 Waveform Generator Block	6-4
6.4.5 Marker Control Block	6-4
6.4.6 YIG Oscillator Control Block	6-4
6.4.7 Modulation and Leveling	6-4
6.5 TROUBLESHOOTING GUIDES	6-5
6.5.1 Power Supplies	6-5
6.5.2 References	6-6
6.5.3 Digital Control Block	6-7
6.5.4 Waveform Generator	6-9
6.5.5 Frequency and Sweep Control	6-15
6.5.6 YIG Oscillator Control Block	6-19
6.5.7 YIG Oscillator	6-21
6.5.8 Modulation and Leveling	6-21

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CONTENTS (Continued)

6.5.9 Marker Control Block	6-23
6.5.10 Display Block	6-25
6.6 TROUBLESHOOTING INDIVIDUAL COMPONENTS	6-27
6.6.1 Transistors	6-27
6.6.2 Diodes	6-28
6.6.3 Operational Amplifiers	6-28
6.6.4 FET Transistor	6-28
6.6.5 Capacitors	6-28
6.6.6 Digital TTL Integrated Circuits	6-28
6.6.7 Reed Relays	6-28
6.6.8 Light Emitting Diodes (LED)	6-28

SECTION 7 PARTS LISTS AND SCHEMATICS

7.1	DRAWINGS	7-1
7.2	ADDENDA	7-1
7.3	ORDERING PARTS	7-1

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SAFETY

This instrument is wired for earth grounding via the facility power wiring. Do not bypass earth grounding with two wire extension cords, plug adapters, etc.

While the very low power of the RF energy generated in this instrument makes it ordinarily nonhazardous, extremely close and prolonged proximity of an eye to the RF output could cause injury.

BEFORE PLUGGING IN the instrument, comply with installation instructions.

MAINTENANCE may require power on with the instrument covers removed. This should be done only by qualified personnel aware of the electrical hazards.

The instrument power receptacle is connected to the instrument safety earth terminal with a green/yellow wire. Do not alter this connection. (Reference: ) or A stamped inside the rear panel near the safety earth terminal.)

WARNING notes call attention to possible injury or death hazards in subsequent operations.

CAUTION notes call attention to possible equipment damage in subsequent operations.

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Series 960 Micro Sweep

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1.1 INTRODUCTION

The 960 Micro Sweep series consist of four compact, lightweight microwave sweep generators that collectively cover the 1 to 18 GHz frequency range. These generators feature three operating modes (Start/Stop Sweep, ΔF Sweep, and CW) with three independently settable frequency markers. Frequency is displayed to 10 MHz resolution on a LCD display.

Frequency can be swept using either of two sweep modes (Start/Stop Sweep and ΔF Sweep). In Start/Stop Sweep, both the start and stop frequencies can be independently set; the Micro Sweep may be swept up or down in frequency. In ΔF Sweep, the center frequency and total frequency deviation each can be controlled; ΔF Sweep sweeps symmetrically upward only. For both sweep modes, the maximum sweep width is 100% of a Micro Sweep's frequency band, while the minimum sweep width is approximately 1%. Both sweep can be auto-triggered (continuous sweep) or triggered which allows the sweep to be started by an external signal. Furthermore, the frequency can be remotely controlled (External Tune) or frequency modulated (FM).

Three independently settable frequency markers can be used in the two sweep modes, CW, and external frequency tuning. These markers may be RF PIP, Z-Axis, or both. Internal switches select the type of marker. Plus, the polarity of the Z-Axis (Intensity markers) output can be set, using internal switches, for either positive or negative intensity control of an oscilloscope trace. In addition, marker intensity or PIP depth also can be set.

Output power is continuously variable. Maximum power is greater than +12 dBm, unleveled, or +10 dBm internally leveled. RF level control range is greater than 25 dB, unleveled, and a nominal 7dB when leveled. An optional internal leveler (Option 001) maintains the output level within ± 1.0 dBm or better across the Micro Sweep's frequency band. The RF output also may be leveled using an external coupler and diode detector. The output can be amplitude modulated (AM) using an external signal.

1.2 SPECIFICATIONS

1.2.1 Frequency Characteristics

Frequency Range

The frequency ranges of the Model 960 Series Micro Sweeps are as follows:

Model 962	1.0 — 4.0 GHz
Model 964	3.7 — 8.4 GHz
Model 965	7.0 — 12.4 GHz
Model 967	12.0 18.0 GHz

Frequency Accuracy

When operated at 25°C ± 10% and maximum RF output, the absolute frequency accuracy of the Model 960 Series Micro Sweep is better than ± 1% (0.5% typical) for CW, ± 1% (typical) for Markers and Center Frequency, and ± 2% (typical) for Start, Stop, and ΔF.

Display Resolution

The front panel display resolution is 10 MHz.

Frequency Stability

The frequency stability (typical) of the Model 960 Series is measured after 1 hour warm-up in a constant environment. Other conditions apply as indicated.

With Temperature	0.007% per °C (0 to +50°C).
With Line Voltage	0.001% with 10% line voltage change.
With Time: Short Term	0.004% over 5 minutes (after 1 hr. warm up and 15 minutes following any fre- quency change).
With Time: Long Term	0.01% over 1 hr. (after 1 hr. warm up and 15 min. follow- ing any frequency change).
With Load (midband 3:1 VSWR)	0.1%.

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Spectral Purity

	Model
	962	964	965	967
Residual FM Peak (50 Hz to 15 kHz post- detection bandwidth)	8 kHz	15 kHz	20 kHz	25 kHz
Spurious	– 55 dBc	– 55 dBc	– 55 dBc	– 55 dBc
Harmonics (maximum)	– 12 dBc*	– 20 dBc	– 20 dBc	– 20 dBc

* For output levels less than - 10 dBm, the harmonic specification is - 10 dBc.

Frequency Control

Manual Tuning: A ten turn control knob sets the CW frequency, marker frequencies, and Center Frequency (CF in ΔF Swp). Two single turn control knobs set the Start, Stop, and ΔF frequencies.

External Tune: 0 to + 10V controls the Micro Sweep for the full tuning range; Swp Time control must be in the Ext Tune position for external frequency tuning.

1.2.2 Operating Modes

Start/Stop Sweep: Sweeps from the frequency set by the Start control to the frequency set by the Stop/ΔF control. Both frequencies are continuously adjustable over full range. Pressing the front panel S/S Swp pushbutton selects the Start/Stop sweep mode. Pushbuttons below the LCD readout select the frequency displayed. Minimum practical sweep width is approximately 1% of band. Downward sweep is permitted but does not provide markers.

Δ F Sweep: Sweeps symmetrically upward, centered on the frequency (CF) set by the main tuning knob. Pressing front panel ΔF Swp pushbutton selects the ΔF sweep mode. Sweep width is set by using the Stop/ΔF sweep control, and the center frequency is set with the main tuning knob. Pushbuttons below the LCD readout select the frequency displayed. Width is adjustable from 100% to less than 1% of the band. Sweeping beyond the frequency limits of the Micro Sweep is not permitted.

CW Operation: Single frequency RF output is controlled by the main tuning knob. Pressing front panel CW mode pushbutton selects the CW mode. An illuminated LED near the main tuning knob indicates when the knob is functioning as CW, Center Frequency, or marker frequency control.

1.2.3 Sweep Capability

Sweep Modes

The two sweep modes (Start/Stop and ΔF Swp) are described in paragraph 1.2.2.

Sweep Time	Continuously adjustable from 0.02 to
	20 seconds, nominal, per sweep.

Sweep Out/Ext Tune In

Internal Sweep Sweep output is 0 to + 10V directcoupled, modified sawtooth waveform regardless of sweep width.

CW Sweep output is linearly proportional to frequency with OV (lowest frequency) to + 10V (highest frequency), nominal, for full Micro Sweep bandwidth.

Frequency Markers

Three constant width markers, independently adjustable over the full frequency band of the Micro Sweep, are available for all sweep functions (Start/Stop, ΔF, and Remote) plus CW. Markers are only produced when the frequency is swept from low to high frequency.

Intensity Marker: A rectangular pulse provides a marker signal for the Z-axis input to oscilloscope. Pulse polarity is factory set for a negative-going pulse, but may be changed to a positive-going pulse via an internal switch (see paragraph 2.2.3 and figure 3-4). Retrace blanking signal will be of the opposite polarity. A front panel trim adjustment permits intensity adjustment.

Amplitude (RF PIP) Marker: The RF PIP marker is generated by momentarily reducing the RF output. (Factory set position enables this type of marker.) The RF PIP maker can be disabled with an internal switch (see paragraph 2.2.3). A front panel trim adjustment permits PIP depth adjustment.

Operation: Marker 1, Marker 2, and Marker 3 are set in any order by first pressing the pushbutton of the desired marker and displaying its frequency on the LCD readout; this activates the marker to accept other commands. The marker being displayed and operated on is identified by a flashing indicator. Markers which are off will blink with a short duty cycle, and markers which are on will blink with a long duty cycle. The marker is then toggled on or off using the On/Off pushbutton. The marker frequency is changed by pressing the Update pushbutton to ''on'' and then adjusting the main turning knob.

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Resolution: Each marker may be set to a digitized resolution of 0.1% of the Micro Sweeps bandwidth. Display resolution is 10 MHz.

Blanking

During retrace, a +5V, nominal, direct coupled rectangular pulse provides the Z-axis input to the oscilloscope. Polarity may be changed to negative by changing an internal switch (see paragraph 2.2.4 and figure 3-4). RF blanking is not provided.

Sweep Trigger

Auto-Trigger: Sweep is automatically triggered on a continuous basis.

External Trigger: A single sweep is triggered by a signal at the front panel Trig In BNC. Pressing the Ext Trig pushbutton selects this mode as indicated by an illuminated Ext Trig pushbutton. The sweep is triggered by the falling edge (high or low) of a TTL signal or a switch contact closure to ground. A double press of the pushbutton

will manually trigger a single sweep at slower sweep rates; there will be a brief delay before the sweep begins.

1.2.4 External Modulation

АМ

Depth	0 to 25 dB min. (30 dB typical) for a 0 to + 10V input.
Bandwidth	50 kHz typical 3dB bandwidth, dc coupled.
Input Impedance	10 kΩ nominal.
M
Deviation	±5MHz min. deviation for ±4V input.
Bandwidth	50 kHz typical, 3dB bandwidth, dc coupled.
Input Impedance	10kΩ nominal.

1.2.5 Output Characteristics

(See table 1-1.)

		М	odel
	962	964	965	967
Output Power Unleveled (without internal leveling option
001)	+ 12 dBm	+ 12 dBm	+ 12 dBm	+ 12 dBm
Leveled (via internal leveling option 001)	+ 10 dBm	+ 10 dBm	+ 10 dBm	+ 10 dBm
Unleveled (with internal leveling option 001 installed	+ 11 dBm	+ 11 dBm	+ 11 dBm	+ 11 dBm
RF Level Control Range
Unleveled Operation Leveled Operation		25 dB minimu 7 dB nominal	ım, 30 dB typica	al.
RF Leveling
Internal Option		Flat ± 1.0 dB	, maximum.
External Leveling (at maximum output using HP 8472A negative polarity detector and 16 dB coupler)		Flat ±0.1 dB maximum, excluding coupler, detector variations.		cluding coupler/
Input Sensitivity		- 50 dB/mV n at front panel	ominal, gain adju	ustment provided
Input Impedance		1kΩ nominal.
Output Impedance		50Ωnominal.
VSWR (with internal leveling option)	<2.5	<1.5	<1.5	<1.5

Table 1-1. Output Characteristics

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1.2.6 General

Connectors

RF Output: Precision Type N. AC Power: CEE22 Type VI. All Others: BNC.

Environment

Operating

Temperature: 0 to + 50°C. Nonoperating - 40 to + 75°C (Rate of temperature change not to exceed 1° per minute). Humidity: 0 to 95% noncondensing. Dimension: 21.6 cm (8½ in.) wide; 9.8 cm (3½ in.) high; 29.9 cm (11¾ in.) deep. Weight: 5.4 kg (12 lb), nominal. Power: 90 - 126V or 198 - 252V; 50 - 400 Hz; 40 VA.

1.2.7 Storage

Short Term (<30 days): Same as Environmental limits; see 1.2.6 General.

Long Term (>30 days): Refer to Preparation for Shipment; see 1.2.6 General.

1.2.8 Options

001 Internal Leveling

1.3 ITEMS FURNISHED

Each Micro Sweep is shipped with an instruction manual and a power cable.

1.4 ITEMS REQUIRED BUT NOT FURNISHED

50Ω BNC and 50Ω Type N coaxial cables are required to interconnect the Micro Sweep to other devices during operation. Items referenced in table 1-2 are required to perform maintenance on the Micro Sweep.

1.5 TEST EQUIPMENT

The tools and test equipment required to perform the checkout procedure, troubleshooting, and calibration procedures are contained in table 1-2.

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Category	Recommended Equipment	Alternate Equipment	Test Equipment Parameters
Oscilloscope	Tektronix 2465	Tektronix 453 Tektronix 475	Sensitivity: 5mV/div. Rise/Fall time: <0.05 μS. Sweep rate: 50 mS/div to 5 μs/div. Trigger: Int and Line
Spectrum Analyzer	Tektronix 492	HP 8559 HP 141T	Range: 1 to 18 GHz. Freq/Division: 10 kHz/div. Bandwidth: 3kHz.
RF Counter, Phase Locking	EIP 575		Range: 5Hz to 10 kHz and 1 to 18 GHz.
RF Power	HP 436A with HP 8484A Power Sensor	Wavetek Pacific Measurements Model 7500	Response: 1 to 18 GHz. Range: +20 to - 40 dBm. Readout: dBm and dBref.
Digital Voltmeter	Fluke 8600A	Fluke 8050A	Range: 19 mV to 19V full scale. Resolution: 4½ digits. Accuracy: ½ LSB.
Test Generator	Wavetek 182A
DC Voltage Source	Fluke 332B	Datel Model DCV-8500	0.0 to +15V.
Oscilloscope Probe	Tektronix P6028	Tektronix P6101	Direct Probe (X1)
Directional Coupler	Krytar 1820	Narda 3292-1	Range: 1 to 18 GHz Coupling: — 16 dB.
Crystal Detector	HP 8470B Option 012		Polarity: Negative. Range: 1 to 18 GHz. Sensitivity: >400 μV/μW.
RF Attenuators	HP 8491B HP 8491B Option 010 HP 8491B Option 040		3dB with Type N connectors, 1 to 18 GHz. 10 dB with Type N connectors, 1 to 18 GHz.
Terminations	Tektronix 5015-1003-00		50Ω, BNC connectors.
Coaxial Adapters	Pomona Model 3285	Tektronix 103-0030-00	BNC Tee.
Coaxial Cables			50Ω BNC (M) to BNC (M). 50Ω Type N (M) to Type N (M).

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SECTION

2.1 MECHANICAL INSTALLATION

After unpacking the instrument, visually inspect all external parts for possible damage to connectors, surface areas, etc. If damaged, file a claim with the carrier who transported the unit. Save the shipping container and packing material in the unlikely event reshipment is required.

The Model 960 Series Micro Sweep is designed primarily for benchtop use. The instrument should be positioned so it rests upon the four rubber feet. The attached tip-up feet may be used to tilt the instrument for a better view of the front panel controls.

CAUTION

When using the instrument, do not obstruct the rear panel heatsink from normal airflow. Also, do not obstruct the top cover of the unit. Both surfaces are used to remove heat from the instrument. A confined operating environment will result in a higher than normal operating temperature and may reduce operating lifetime.

Wherever possible, place the unit in an area where air currents over the rear panel heat sink remain constant. Changes in air velocity over the heat sink will result in temperature changes at the YIG-tuned oscillator and corresponding slight frequency shifts.

2.2 ELECTRICAL INSTALLATION

2.2.1 Power Connection

NOTE

Unless otherwise specified at the time of purchase, this instrument was shipped from the factory with the power transformer connected for operation on a 120Vac line supply and with an 1 amp slow blow fuse.

Conversion to the 220 Vac input setting requires a change in rear panel fuse holder voltage card position and fuse (figure 2-1) according to the following procedure.

Card Position	Input VAC	Fuse (Slo-Blo)
100	100 to 125	1amp
120	100 to 125	1amp
220	200 to 250	1/2 amp
240	200 to 250	1/2 amp

1. Disconnect the power cord at the rear of the instrument and open fuse holder cover door. Rotate the fuse-pull level down to remove the fuse.

Figure 2-1. Voltage Selector and Fuse

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2. Remove the small printed circuit board and select either the 120 or 220 volt positions by orienting the printed circuit board to position the desired voltage to the upper right when facing the rear of the unit. The desired voltage setting should be visible after inserting the card in the slot. Push the board firmly into its module slot.
3. Return the fuse-pull lever to the up position and insert the correct fuse into the fuse holder. Close the cover door.
4. Reconnect the power cord to the mating connector at the rear of the unit and then to the power source.

2.2.2 Signal Connection

When connecting the RF Output connector to associated equipment, use 50 \Omega coaxial cables equipped with male type N connectors that are compatible with those specified in US MIL-C-39012. Use mating BNC connectors with 50 \Omega coaxial cable for all other input and output connections.

CAUTION

Reverse power input to the Model 960 Series in excess of 20 mW may damage the output circuits.

2.2.3 Marker Type Selection

There are two types of markers available in the 960 micro sweeps: Intensity and RF PIP. Either one of these types or both may be selected by a switch SW2 inside the micro sweep. Micro Sweeps are preset to provide Intensity and RF PIP Markers when shipped. The magnitude of the marker can be adjusted using the front panel Mkr Adj adjustment; refer to paragraph 3.1, Mkr Adj.

To select the marker.

1. Disconnect the micro sweep from the power source.
2. To remove the top cover, remove the two screws at the rear of the cover and lift the cover off. It is usually possible to set the top cover with the power supply cable still attached to the left of the Micro Sweep. If the top cover needs to be disconnected from the Micro Sweep, refer to figure 2-2.
3. Set SW2, located on the Main Board (refer to figure 2-2), for the desired marker type; refer to the following table. It may be easier to remove the WaveGen board before setting the switch SW2.

SW2 Settings

Switch Position
1	2	3	4*	5	Marker Type
Closed	Open	Open	х	Closed	Intensity Marker
Open	Closed	Open	х	Closed	RF PIP Marker
Closed	Open	Closed	Х	Closed	Intensity and RF PIP Markers

* Refer to paragraph 2.2.5; Tuning Filter Settings X Do not care.

4. Connect the cables, if disconnected, and replace the top cover.

2.2.4 Z-Axis Blanking Polarity Selection

Switch SW1, located on the WaveGen board, allows selection of the Z-axis blanking pulse polarity, either positive-going (0 to + 5V) or negative-going (+ 5 to 0V) pulse. The Micro Sweeps are shipped set for positive going blanking pulses.

To select the Z-axis blanking polarity.

1. Disconnect the Micro Sweep from the power source.
2. To remove the top cover, remove the two screws at the rear of the cover and lift the cover off. Note: the power supply module is attached to the top cover and may need to be disconnected See figure 2-2.
3. Set SW1, located on the WaveGen Board, for the desired polarity; refer to the following table.

S	W	1	S	ei	ti	n	a	ş
-		-	_				-	-

Switch Position
1	2	3	4	5	Z Axis Polarity
NC	Closed	Open	Open	Closed	Positive-going
NC	Open	Closed	Closed	Open	blanking pulse Negative-going blanking pulse

NC Not connected.

4. Connect the cables, if disconnected, and replace the top cover.

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2.2.5 Tuning Filter Selection

SW2 position 4 allows enabling or disabling of the tuning filter in the CW mode. Micro Sweeps are preset to the enabling mode (SW2-4 closed) when shipped. To disable the filter, open SW2-4.

To select the tuning filter.

1. Disconnect the Micro Sweep from the power source.
2. To remove the top cover, remove the two screw at the rear of the cover and lift the cover off. Note: the power supply module is attached to the top cover and may need to be disconnected; see figure 2-2.
3. Set SW2 position 4, located on the Main board, to Open to disable the filter (fast tuning) and to Closed to enable the filter (low residual FM).
4. Connect the cables, if disconnected, and replace the top cover.

2.3 INITIAL CHECKOUT PROCEDURE

The procedure in table 2-1 provides an initial operational checkout of all controls, connectors, and indicators located on the front and rear panels of the Micro Sweep. Each operational test requiring test equipment has the equipment interconnection illustrated and referenced in the Equipment and Setup column. The Micro Sweep Checkout Record (table 2-2) may be copied and used for a permanent record of the unit's test.

The test equipment, or its equivalent, required for the checkout procedure is listed in table 1-1.

Figure 2-2. Switch Location

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Step	Test	Equipment/Setup	Controls and Indicators	Desired Results
1	Primary Power	None	Facility power: off.	Verify correct fuse installed. Verify cor- rect primary voltage selected.
2		Connect Micro Sweep to facility power source.	Facility power:on. Power switch: On.	Line LED lit.
3	Power up conditions			CW Mode LED lit. CW indicator by main tuning knob is lit.
4	RF On		RF On: On. (Allow 15 minutes for Micro Sweep to warm up.)	RF On indicator is lit.
5	CW Output frequency	See figure 2-3.	Main Tuning Knob: full ccw. Mode: CW.	Micro Sweep display reads at or below specified low end of Micro Sweep frequency range.
			FF Level: full Cw.	Counter reads Micro Sweep display fre- quency ±1%. (Must be at or below specified low end of Micro Sweep fre- quency range.)
6			Main Tuning Knob: full cw.	Micro Sweep display reads at or above specified high end of Micro Sweep frequency range.
				Counter reads Micro Sweep display fre- quency ±1%. (Must be at or above specified high end of Micro Sweep fre- quency range.
7	Output Level Vs Frequency, Micro Sweeps without Internal Leveler (Option 001)	See figure 2-4. NOTE Account for power sensor error in order to reduce measure- ment errors. Do not exceed maximum input to power meter.	Main Tuning Knob: full ccw. RF Level: full cw. Ext Level: Off. Ext Level indicator not lit. Lev indicator not lit.	RF output level ≥ + 12 dBm.
8			Main Tuning Knob: turn cw in 0.1 GHz (as indicated on Micro Sweep display).	RF level remains ≥ + 12 dBm as fre- quency is varied.

Table 2-1. Initial Checkout Procedure

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Step	Test	Equipment/Setup	Controls and Indicators	Desired Results
9	Output Level Vs Frequency, Micro Sweeps with Internal Leveler (Option 001)	See figure 2-4. NOTE Account for power sensor error in order to reduce measure- ment errors. Do not exceed maximum input to power meter.	Main Tuning Knob: full ccw. RF Level: full cw. Ext Level: Off. Ext Level indicator not lit. Lev indicator lit.	RF output level ≥ + 10 dBm.
10			Main Tuning Knob: turn cw in 0.1 GHz steps (as indicated on Micro Sweep display).	RF level remains ≥ + 10 dBm as fre- quency is varied.
11			Main Tuning Knob: full ccw. Ext Level: On. Ext Level indicator lit. Lev indicator not lit.	RF output level ≥ + 11 dBm.
12			Main Tuning Knob: turn cw in 0.1 GHz steps (as indicated on Micro Sweep display).	RF level remains ≥ + 11 dBm as fre- quency is varied.
13	Output Attenua- tion, Micro Sweep without Internal Level- ing (Option 001)		Main Tuning Knob: full ccw. RF Level: full ccw. Ext Level: Off. Ext Level indicator not lit. Lev indicator not lit.	Power meter reads at least 25 dB less than level recorded in step 7.
14	Output Attenua- tion, Micro Switch with Internal Level- ing (Option 001)		Main Tuning Knob: full ccw. RF Level: full ccw. Ext Level: Off. Ext Level indicator not lit. Lev indicator lit.	Power meter reads at least 7dB less than level recorded in step 10.

Table 2-1. Initial Checkout Procedure (Continued)

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Step	Test	Equipment/Setup	Controls and Indicators	Desired Results
15	External Level Control	See figure 2-5. NOTE Account for power sensor error in order to reduce measure- ment errors. Do not exceed maximum input to power meter.	Main Tuning Knob: full ccw. RF Level: full cw. Ext Level: On. Ext Level indicator lit. Lev indicator lit.	Note RF output level reading.
16			Main Tuning Knob: turn cw in 0.1 GHz steps (as indicated on Micro Sweep display).	RF level varies less than ±1 dB as frequency is varied.
17	Sweep Out Ramp	See figure 2-6.	Mode: S/S Swp. Start: full ccw. Stop/∆F: full cw. Swp Time: full cw.	Oscilloscope displays approximately ≤20 ms sweep time. See figure 2-7.
18			Swp Time: full ccw. NOTE If this control is acci- dentally placed in the Ext Tune posi- tion, the unit reverts to the CW mode.	Oscilloscope displays approximately ≥20 second sweep time.
19	S/S Sweep	See figure 2-8.	Mode: S/S Swp (indi- cator lit). Start: full ccw. Stop/∆F: full cw. Swp Time: full cw.	Oscilloscope verifies Start/Stop fre- frequency sweep. See figure 2-9.
20			Start: rotate cw; return to full ccw.	Start frequency increases; sweep range decreases.
21			Stop/∆F: rotate ccw; return to full cw.	Stop frequency decreases; sweep range decreases.

Table 2-1. Initial Checkout Procedure (Continued)

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Step	Test	Equipment/Setup	Controls and Indicators	Desired Results
22	Markers	See figure 2-8.	Start: full ccw. Stop/∆F: full cw. M1: press (indicator flashes at low duty cycle). On/Off: press once (M1 flashes at high duty cycle). Update: press Main Tuning Knob: ccw to lower end of band.	Oscilloscope displays marker number 1 on left half of trace; see figure 2-9. Note It may be necessary to adjust the Mkr Adj or the marker polarity for proper display. Refer to paragraph 2.2.4.
23			M2: press (indicator flashes at low duty cycle). M1 indicator on continuously. On/Off: press once (M2 flashes at high duty cycle). Update: press Main Tuning Knob: cw to upper end of band.	Oscilloscope displays marker number 2 on right half of trace; see figure 2-9.
24			M3: press (indicator flashes at low duty cycle). M1 and M2 indicator on continuously. On/Off: press (M3 flashes at high duty cycle). Update: press Main Tuning Knob: near center of frequency band.	Oscilloscope displays marker number 3 near center of trace; see figure 2-9.
25	ΔF Sweep		Mode: ΔF Swp. Main Tuning Knob: center of frequency band. Display Stop/ΔF: press Stop/ΔF: center of range.	Oscilloscope verifies ∆F sweep. Marker number 3 appears in the center of the trace; see figure 2-10.

Table 2-1. Initial Checkout Procedure (Continued)

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Step	Test	Equipment/Setup	Controls and Indicators	Desired Results
26	∆F Sweep	See figure 2-8.	Stop/AF: rotate cw.	Sweep range increases as verified on oscilloscope.
27			Stop/AF: rotate ccw.	Sweep range decreases as verified on oscilloscope.
28	External Trigger	See figure 2-11.	Mode: ΔF Swp. Main Tuning Knob: center of frequency band. Stop/ΔF: full cw. Ext Trig: On (indica- tor lit). Swp Time: full cw.	Oscilloscope verifies externally trig- gered ΔF sweep.
29	Single Sweep	Figure 2-11 without TTL source TRIG IN.	Ext Trig: On. Sweep Time: center of range (12 o'clock). Ext Trig: press twice.	Ext Trig indicator is lit. Oscilloscope displays a single trace each time Ext Trig is pressed twice.
30	External Frequency ·Modulation	Set up as shown in figure 2-12.	Mode: CW. Main Tuning Knob: center of frequency band.	Spectrum analyzer verifies 1kHz FM signal.
31	External Amplitude Modulation	Set up as shown in figure 2-13.	Mode: CW. Main Tuning Knob: center of frequency band. RF Level: cw.	Oscilloscope displays square wave with frequency of 1kHz. (Adjust RF Level to obtain desired detection range on oscilloscope.)
32	External Frequency Control	Set up as shown in figure 2-14. DC Source: 0V	Swp Time: ' extreme ccw (Ext Tune).	Ext Tune indicator lit. Micro Sweep dis- play reads low end of unit's frequency range.
33		DC Source: + 10 ± .02V.		Micro Sweep display reads high end of unit's frequency range.

Table 2-1. Initial Checkout Procedure (Continued)

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Figure 2-3. Frequency Measurement Setup

Figure 2-4. Output Level Measurement Setup

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Figure 2-5. External Level Control Setup

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Figure 2-7. Sweep Ramp and Blanking Pulse Output

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Figure 2-14. External Frequency Control Setup

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Step (Table 2-1)	Desired Results	Acceptable (∠)
1	Correct fuse installed. Correct voltage selected.
2	Line LED lit.
3	CW indicators lit.
4	RF LED indicator is lit.
5	Micro Sweep tunes to low end of frequency range. Counter reads Micro Sweep frequency ±1%.
6	Micro Sweep tunes to high end of frequency range. Counter reads Micro Sweep frequency ±1%.
7	Micro Sweep without Internal Leveler. RF output level ≥ + 12 dBm.
8	Micro Sweep without Internal Leveler. RF level remains ≥ + 12 dBm (minimum).
9	Micro Sweep with Internal Leveler. RF output level ≥ + 10 dBm.
10	Micro Sweep with Internal Leveler. RF level remains ≥ + 10 dBm.
11	Micro Sweep with Internal Leveler; Internal leveler off. RF output level ≥ + 11 dBm.
12	Micro Sweep with Internal Leveler; Internal leveler off. RF level remains ≥ + 11 dBm.
13	Micro Sweep without Internal Leveler or Micro Sweep with Internal leveler off. RF power meter reads at least 25 dB less than step 7.
14	Micro Sweep with Internal Leveler. RF power meter reads at least 7dB less than in step 10.
15	Note RF output level reading.
16	RF level varies ≤ ± 1 dB of reading in step 15.

Table 2-2. Micro Sweep Checkout Record

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Step (Table 2-1)	Desired Results	Acceptable ()
17	Oscilloscope verifies approximately ≤20 ms sweep time.
18	Oscilloscope verifies approximately ≥20 second sweep time
19	Oscilloscope verifies Start/Stop frequency sweep
20	Start frequency increases. Sweep range decreases
21	Stop frequency decreases. Sweep range decreases.
22	Oscilloscope displays Marker 1
23	Oscilloscope displays Marker 2
24	Oscilloscope displays Marker 3
25	Oscilloscope verifies AF Sweep
26	Sweep range increases as verified on oscilloscope
27	Sweep range decreases as verified on oscilloscope.
28	Oscilloscope verifies External Trigger
29	Oscilloscope verifies manual single sweep
30	Spectrum Analyzer verifies 1kHz FM signal
31	Oscilloscope displays 1kHz square wave
32	Frequency counter and Micro Sweep display read low end of Micro Sweep frequency range.
33	Frequency counter and Micro Sweep display read high end of Micro Sweep frequency range

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3.1 CONTROLS, CONNECTORS, AND INDICATORS

The Micro Sweeps front and rear panel controls, indicators, and connectors are shown in figure 3-1 and keyed to the following description.

1 Main Tuning Knob

This ten-turn manual frequency control knob sets three different types of frequency parameters, depending upon the operating and display mode of the instrument.

In the CW mode, it tunes the frequency of the microwave oscillator. In the ΔF sweep mode, the control sets the center frequency (CF) of the symmetrical sweep.

When a marker (M1 through M3) has been selected and the Update pushbutton 3 has been pressed, this control set the marker frequency.

Selecting the start/stop sweep mode (S/S Swp) or external tune (Ext Tune) disables the main tuning knob.

The three LED indicators to the right of the main tuning knob indicate which frequency parameter is being controlled by the knob.

2 Tuning Indicators

CW This red LED is illuminated when in the CW mode. The Main Tuning Knob 1 tunes the frequency of the microwave oscillator in the CW mode.

CF (Center Frequency) This red LED is illuminated when in the ΔF Sweep mode. The Main Tuning Knob 1 controls the center frequency in ΔF sweep.

Mkr (Marker) This red LED is illuminated when the Main Tuning Knob 1 is used to update any marker frequency. It is activated whenever the Update 3 switch is toggled on. For a marker frequency to be updated, a marker must have first been selected by pressing any of the switches M1 through M3. The Mkr LED may be on simultaneously with the CW or CF LED.

3 Marker Switches

M1 (Marker 1) This momentary contact pushbutton switch and integrated red LED indicator are used to select marker number 1 for frequency display and status change via the On/Off or Update switches. Pressing the switch displays the frequency of Marker 1 on the LCD readout, enables status change, and causes the LED to blink. If the selected marker 1 is on, the blink has a long duty cycle (mostly on). If the marker 1 is off, the blink has a short duty cycle (mostly off). If the marker is on but not selected for change, the LED is illuminated without blinking.

M2 (Marker 2) This switch and indicator functions exactly the same as the M1 marker switch and indicator, except Marker 2 is selected.

M3 (Marker 3) This switch and indicator functions exactly the same as the M1 marker switch and indicator, except Marker 3 is selected.

On/Off This momentary contact pushbutton switch changes the on/off status of a selected marker. If the selected marker is off, blinking with a mostly off (short duty) cycle, pressing the On/Off switch will turn on the marker and the blink duty cycle will become long (mostly on). If the selected marker is on, pressing the On/Off switch will turn the marker off.

Update This momentary contact pushbutton switch with integrated LED indicator activates the marker frequency tuning mode after a marker has been selected. Pressing this switch allows the Main Tuning Knob 1 to update the frequency of the selected marker. The marker update mode is indicated by the glowing LED indicator within the switch and the Mkr LED next to the Main Tuning Knob 1. Pressing any other front panel pushbutton switch cancels the marker update mode. If the Update switch is pressed without a marker being selected, the Update indicator will glow, but no marker frequencies will be changed.

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4 Mode Switches and Indicators

CW This momentary contact pushbutton switch with integrated LED indicator selects and indicates the CW mode of operation. Pressing the switch selects the CW tuning mode. When the CW mode has been selected, the LED inside the switch is illuminated. The CW mode is also indicated by the CW LED 2 to the right of the Main Tuning Knob 1. When the unit has been placed into the external tune (Ext Tune) mode, the CW mode is automatically selected and the LED indicators glow. Selecting the CW or external tuning mode of operation also switches a filter into the microwave oscillator tuning circuit which improves the residual FM performance. This filter reduces the response of the oscillator to rapid changes in frequency during the CW mode. The tuning filter can be disabled by a switch within the instrument; refer to paragraph 2.2.5.

S/S Swp This momentary contact pushbutton switch with integrated LED indicator selects and indicates the Start/Stop Sweep mode. Pressing the switch selects the Start/Stop mode. When the Start/Stop mode has been selected, the LED inside the switch is illuminated.

Δ F Swp This momentary contact pushbutton switch with integrated LED indicator selects and indicates the ΔF Sweep mode of operation.

5 RF Level Control This single turn manual control knob sets the RF output Power level. When rotated cw, the RF output level is increased. When rotated ccw, the RF output level is decreased.
6 RF On The momentary pushbutton and LED indicator enables or disables the signal at RF Output 7 . If the indicator is illuminated, the RF output is on; if the indicator is out the RF output is off (the actual YIG oscillator is shut off).
7 RF Output This N-Type connector provides a 50Ω output for the RF signal from the instrument.
8 Ext Level This momentary pushbutton and LED indicator switches the unit to accept a leveling input from the front panel ALC In BNC 9. If the LED is not glowing, the unit attempts to level with the internal leveling option, if installed.
9 ALC In This connector accepts a signal input which, when Ext Level 8 is selected, is used to level the RF output across the frequency band.

10 Lev An illuminated LED indicates that the RF output signal is leveled either internally or externally.
11 Lev Adj This screwdriver adjustment allows adjustment of the leveling loop gain. It has been factory preset for optimal leveling loop operation. When using different couplers and detectors, the Lev Adj may require further adjustment to optimize leveling loop performance and to prevent leveling loop oscillation.
12 Trig In This input allows external triggering of the sweep. Sweep is triggered by the falling edge of a TTL signal or contact closure to ground.
13 Ext Trig This momentary pushbutton with LED indicator selects either externally triggered sweep or auto-triggered sweep. When external trigger is selected (Ext Trig indicator lit), an external trigger signal or contact closure at the Trig In connector 12 triggers the sweep. Double pressing of this pushbutton at slower sweep rates permits single sweep operation. When auto-trigger is selected (Ext Trig indicator extinguished), the frequency is continuously swept.
14 Mkr Adj This front panel screwdriver adjustment adjusts the magnitude of the markers. If intensity markers are used, this control adjusts the relative brightness of the markers. If RF PIP markers are used, this control adjusts the depth of the PIP. When both markers types are used, the adjustment only affects the brightness of the intensity marker.
15 AM In This BNC connector provides an input port for external AM signals. A dc input at this port will remotely control the Micro Sweep's RF output level.
16 Swp Time This control sets the sweep time for the S/S Swp and ΔF Swp modes. The sweep time can be varied between 0.02 to 20 seconds, nominal. In addition, a detent position (Ext Tune) allows an analog signal at the Swp Out/Ext Tune In connector 25 (rear panel) to control the oscillator frequency; the unit is automatically switched to the CW mode.
17 ExtTune This LED, when lit, indicates the Swp Time control 16 is set to the Ext Tune position.
18 Stop/ΔF This single turn control sets either the stop frequency (S/S Swp mode) or ΔF frequency (ΔF Swp mode) depending on the sweep mode as determined by the Mode switches 4 .

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19 Display Stop/ΔF This momentary pushbutton (indicator lit) causes the display to show either the stop frequency (S/S Swp mode) or ΔF frequency (ΔF Swp) depending on the existing sweep mode. The Display Stop/ΔF pushbutton has no affect in the CW mode.
20 Start This control sets the start frequency in the S/S Swp mode.
21 Display Start/CF This momentary pushbutton (indicator lit) causes the display to show either the start frequency (S/S Swp mode) or CF frequency (ΔF Swp mode). The Display Start/CF indicator will light automatically when the S/S Swp mode or the ΔF Swp mode is initially selected.
22 Power On/Off This pushbutton controls the primary power to the unit. When the power is on the Line LED indicator is lit. When the power is off the Line LED indicator is extinguished.
23 Sweep This indicator lights for the duration of the sweep in the S/S Swp and ΔF Swp modes.
24 (Frequency) GHz This 3½ digit liquid crystal display (LCD) indicator displays the CW frequency (CW mode), start or stop frequency (S/S Swp mode), and center and ΔF frequencies (ΔF Swp mode). It also can be switched to display the frequencies of markers 1 through 3 and the externally tuned frequency.
25 Swp Out/Ext Tune In This rear panel BNC connector serves two functions depending upon the setting of the Swp Time 16 control. For internal sweep modes, this connector supplies a 0 to + 10V directcoupled, modified sawtooth waveform. The Swp Time control can be in any position except Ext Tune (detent). The signal limits are 0V (sweep beginning) and + 10V (sweep end) regardless of sweep width, rate or direction. In the internal CW mode, the output is proportional to the frequency with linear 0 to + 10V, nominal, for full instrument bandwidth.

When the Swp Time control is set to the Ext Tune position (detent), this connector accepts a 0 to + 10V input level that tunes the microwave oscillator from the bottom of the band to the top of the band respectively.

26 Power cord connector This combination connector provides a line voltage selector and fuse holder as well as a connector for a modular line cord.

27 Z-Axis Out This BNC connector provides the rectangular marker (Intensity Marker) pulse and retrace blanking pulse for Z-Axis input to CRT display units. The polarity of the marker output is factory set to a negative pulse with a corresponding positive blanking pulse. The pulse may be changed to the opposite polarity by an internal switch; see paragraph 2.2.4.
28 FM In This rear panel BNC connector provides an input port for external FM or phase-lock feedback signals.

3.2 OPERATION

The following paragraphs describes how to use the 960 Series Micro Sweep. All bold numbers in the text refer to the individual controls and connectors described in paragraph 3.1. Also, paragraph 2.3 and table 2-1 provides an excellent hands-on method of understanding the 960s' operation.

3.2.1 CW Operation

In the CW mode, the Micro Sweep supplies a single frequency at the RF Output connector 7 . The main tuning knob 1 sets the output frequency. The signal can be FM modulated (FM, see paragraph 3.2.8), and AM modulated (AM, see paragraph 3.2.7). The External Tuning mode is similar to the CW mode except the frequency is controlled by an external signal. Figure 3-2 illustrates the control settings and equipment setup for the CW mode.

The following list gives the controls and connectors required for the CW operating mode.

Control/Connector	Operation
Power 22	Press to turn unit on. Line LED is lit.
RF On 6	Press to On (indicator lit) to enable RF signal at RF Output.
RF Level 5	Set RF level at RF Output con- nector to desired output level.
Mode 4	Press CW pushbutton (indi- cator lit) to select CW (if necessary).
LCD Display 24	Shows output frequency.

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Control/Connector	Operation
CW LED 2	Lit indicates that main tuning knob controls the CW frequency.
Main Tuning Knob 1	Sets output frequency. Rotate cw to increase frequency and ccw to decrease frequency. Rotate cw to increase output level and ccw to decrease.
RF Output 7	Signal output from the unit. 50Ω source impedance.
Swp Out/Ext Tune In (Rear Panel) 25	A 0 to + 10V dc level propor- tional to the output frequency main tuning knob).

3.2.2 Start/Stop Sweep

In Start/Stop Sweep (S/S Swp), the frequency sweeps linearly between a set Start frequency and a set Stop frequency. The Start knob 20 controls the start frequency. and the Stop/AF knob controls the stop frequency. The Display Start/CF 21 and Display Stop/∆F 19 selects either the Start or Stop frequency for display. The Swp Time (Sweep Time) knob 16 sets the sweep rate. Frequency markers can be used with Start/Stop Sweep; refer to paragraph 3.2.5. Figure 3-3 illustrates the controls and equipment setup for the Start/Stop Sweep operation.

The following list gives the controls and connectors reauired for the Start/Stop Sweep operating mode.

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Figure 3-4. Sweep Sawtooth and Blanking Pulse Output

3-5

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Figure 3-5. △F Sweep Operation

Control/Connector

LCD Display 24

Main Tuning Knob

Operation

Shows the center frequency.

Sets the center frequency.

Rotate cw to increase fre-

3.2.3 AF Sweep

In the AF Sweep mode, the frequency sweeps symmetrically upward centered on the center frequency (CF). The Main Tuning knob 1 sets the center frequency, while the Stop/AF knob 18 sets the total frequency deviation. The Swp Time knob controls the sweep rate. Frea ра

pushbutton need not be pressed if the indicator is lit.

quency markers can paragraph 3.2.5. Figu trols for the ΔF Sweet	be used with ΔF Sweep; refer to re 3-5 indicates the primary con- p operation.		frequency.
The following list giv	es the controls and connectors	Display Stop/AF 19	Press to display total frequency deviation (indicator lights).
Control/Connector	Operation	LCD Display 24	Shows the total frequency deviation.
Power 22	Press to turn unit on. Line LED is lit.	Stop/ΔF 18	Sets the total frequency devia- tion. Rotate cw for maximum deviation and ccw for minimum
RF On 6	Press to On (indicator lit) to enable BE signal at BE Output.		deviation.
RF Level 5	Set RF level at RF Output con- nector. Rotate cw to increase output level and ccw to decrease.	Swp Time 16	Sets the sweep rate; can be varied between 0.02 (cw posi- tion) to 20 (ccw position) seconds. If the Swp Time switch is accidentally placed in the Ext Tune position, the unit
RF Output 7	Signal output from the unit. 50Ω source impedance.		reverts to the CW mode.
		Sweep LED 23	Blinks at sweep rate.
Mode 4	Press ΔF Swp pushbutton (indicator lit) to select ΔF Sweep mode. CF LED 2 is lit.	Swp Out/Ext Tune In (rear panel) 25	A 0 to + 10V dc coupled, modi- fied sawtooth wave; see figure 3-4.
Display Start/CF 21	Press to display center fre- quency (indicator lit), this

3-6

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Figure 3-6. External Triggered Sweep Operation

3.2.4 External Triggered Sweep

The unit may be externally triggered by applying an signal at the Trig In BNC or manually triggered using the Ext Trig pushbutton When triggered, the unit sweeps, either Start/Stop Sweep or A F Sweep, one time and returns to the original point. Figure 3-6 shows the controls and connectors required for the external triggered sweep mode

The following list gives the controls and connectors required for triggered sweep.

Control/Connector	Operation
Power 22	Press to turn unit on. Line LED is on.
RF On 6	Press to On (indicator lit) to enable RF signal at RF Output
RF Level 5	Set RF level at RF Output con- nector. Rotate cw to increase output level and ccw to decrease.
RF Output 7	Signal output from the unit. 50Ω source impedance.
Mode 4	Select the desired sweep mode. For Start/Stop Sweep, refer to paragraph 3.2.2. For ΔF Sweep, refer to paragraph 3.2.3.

Control/Connector	Operation
Ext Trig 13	Press to select externally trig- gered sweep, indicator is lit.
Trig In 12	To initiate a triggered sweep, apply a high to low TTL signal or contact closure to ground.

To manually trigger the sweep in external trigger, press the Ext Trig pushbutton twice. In order to effectively manually trigger, the sweep time must be slower than the rate at which the pushbutton is pressed. There is an initial retrace recovery delay before the sweep begins.

3.2.5 Frequency Markers

The Micro Sweep can supply up to three constant width frequency markers for CW, Start/Stop Sweep, A F Sweep, and Remote frequency control. Each marker is independently adjustable over the entire frequency band. The unit supplies two types of markers: Oscilloscope Z-Axis Intensity and Amplitude (RF PIP). The marker type can be selected using an internal switch; refer to paragraph 2 2.3. Frequency markers are provided only when the sweep is from a lower to higher frequency.

Intensity markers, a rectangular pulse, provides a marker signal for Z-axis input to oscilloscopes. The marker pulse is factory set for a negative-going pulse (u), but may be changed to positive-going pulse (n) using an internal switch; refer to paragraph 2.2.4. Retrace blanking signal will be of the opposite polarity.

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Amplitude (RF PIP) ma	rker is generated by momentarily t. The factory set position enables	Control/Connector	Operation
the amplitude marker, an internal switch; ref	however, it can be disabled with fer to paragraph 2.2.4.	M1 3	Press to select Marker 1. The M1 indicator flashes with a low
Figure 3-7 shows the guency markers. Cor	controls required to set the fre-		duty cycle (mostly off)
Sweep or ΔF Sweep a and 3.2.3 respectively	re described in paragraphs 3.2.2	LCD Display 24	Shows the frequency of Marker
The following list give required to set freque order to selecting, ena	es the controls and connectors ncy markers. There is a specific bling, and changing the markers.	On/Off 3	Press once to turn on marker 1. M1 indicator blinks at a high duty cycle (mostly on).
This example sets m markers (M2 and M3)	arker number 1, the other two are set the same way.	Update 3	Press once to update marker 1. The Update indicator lights: the
Control/Connector Operation			M1 indicator remains flashing.
Power 22	Press to turn unit on. Line LED is on.		the main tuning knob controls the marker.
RF On 6	Press to On (indicator lit) to enable RF signal at RF Output.	Main Tuning Knob 1	Turn cw or ccw to set marker 1 to desired frequency as shown on the LCD Display 23 .
RF Level 5	Set RF level at RF Output con- nector. Rotate cw to increase	Mode 4 .	Press any mode or display
	output level and ccw to decrease.	Display Start/CF 21 , or Display Stap/AF	button to leave the marker set- up mode. M1 indicator stops
RF Output 7	Signal output from the unit. 50Ω source impedance.	19	nashing and remains it.
Mode 4	Select the desired sweep mode. For Start/Stop Sweep, refer to paragraph 3.2.2. For ΔF Sweep, refer to paragraph	Z-Axis Out 27	A rectangular pulse to intensity modulate an oscilloscope; see Intensity Modulation in this paragraph and figure 3-4.
	3.2.3. For Ext Tune, refer to paragraph 3.2.9.	Mrk Adj 14	Adjust for proper intensity on oscilloscope.

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Figure 3-8. External Leveling Operation

3.2.6 ALC/Leveling

Leveling allows the RF output signal to be flat over the entire unit's frequency band. There are two types of leveling in the Micro Sweep: Internal (Option 001 required) and External Leveling can be used with all modes of operation.

With Option 001 installed, internal leveling is automatic whenever external leveling is not selected and the RF power is on. The Lev indicator is lit. Refer to paragraph 1.2.4 for level limitations.

To use external leveling, setup the Micro Sweep as shown in figure 3-8, then press the Ext Level 8 so its indicator is lit. The Lev indicator 10 will light when a proper leveling signal is present at the ALC In connector. The Lev Adj control 11 sets the leveling loop gain.

3.2.7 Amplitude Modulation (AM)

The output level may be amplitude modulated by using external signal at the AM In. This signal may be either ac or dc. A dc level at the AM In connector may be used to remotely control the output level. The Micro Sweep will respond unidirectionally and logarithmically to the external modulating signal. For example: a 0 to + 10V input (+ 10V is maximum attenuation) will decrease the signal level, while a 0 to -10V input will have no affect. To achieve maximum depth of modulation, set the RF Level to full cw. Figure 3-9 shows the controls and connectors required for Amplitude Modulation. The unit may be amplitude modulated in any mode.

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3.2.8 Frequency Modulation

The micro source's frequency may be modulated by an ac or dc signal. Figure 3-10 shows the controls and connectors required for frequency modulation. In addition, the FM In can be connected to the phase lock output of a phase locking counter to achieve the frequency accuracy of the counter's internal time base.

3.2.9 External Tuning

When the Swp Time knob is set to Ext Tune (the detent position), an external level controls the frequency of the microwave oscillator. Selecting Ext Tune automatically

places the Micro Sweep in the CW mode. A OV (minimum frequency) to + 10V (maximum frequency) level controls the oscillator. Figure 3-11 shows the controls and connections required for external frequency tuning. An internal tuning filter which filters the YIG tuned oscillator tuning current, can be switched in or out; see paragraph 2.2.6. If the external tuning signal is changing at a fast rate (>1V/second) or it is important to optimize frequency tracking during switching, the filter should be switched out (reduced filtering). When external tuning is used in conjunction with a source locking counter or any application requiring low residual FM, the filter should be switched in (maximum filtering); this is the factory setting.

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Figure 4-1. 960 Series Overall Block Diagram

4-0

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4.1 GENERAL DESCRIPTION

The Model 960 series consist of four microwave sweep generators that cover the following frequency ranges.

Model 962 1.0—4.0 GHz Model 964 3.7—8.4 GHz Model 965 7.0—12.4 GHz Model 967 12.0- 18.0 GHz

All four Micro Sweep models contain identical circuits; the only difference is the YIG Oscillator and related calibration adjustments Figure 4-1 shows the major circuits within the Micro Sweep and their relationships. Circuits are divided between five circuit boards: Main Circuit, Marker Circuit, Waveform Generator Circuit, Digital Control Circuit, and Display. Most major circuits are located on their respective board, however some circuits have sections located on several boards.

4.1.1 Power Supplies

A modular power supply attached to the top cover converts the primary ac power into + 16V dc and - 16V dc. These supplies provide the input voltage for the four other supplies: ±13V and ±6.3V used within the Micro Sweep.

4.1.2 References

There are three reference sources used in the Micro Sweep: +10 REF, +10_BUF, and -10_REF. The fundamental reference is the +10 REF; the other references are derived from this reference. These sources provide the accurate, high stability voltages required for various circuits in the instrument. All references are generated by a heater controlled zener diode.

4.1.3 Digital Control

When a front panel pushbutton is pressed, the Digital Control block decodes the transition and enables the appropriate control line or lines. These control lines control the various circuits within the Micro Sweep. The Digital Control block enables all front panel indicators except the frequency display.

4.1.4 Waveform Generator

The Waveform Generator block produces the Micro Sweep's internal modified sawtooth waveform and blanking pulses. To produce the modified sawtooth waveform, a constant current source charges a timing capacitor, a comparator detects the peak and discharges the timing capacitor. Two clippers limit the top and bottom peaks of the waveform The front panel Sweep Time control varies the charging current supplied by the constant current source. The modified sawtooth waveform also can be externally triggered by enabling and disabling the comparator. Normally, the waveform generator retriggers itself (Auto-trigger). However, an external trigger signal can enable the Waveform Generator to produce one modified sawtooth waveform per trigger signal. The Waveform Generator also produces a blanking pulse which is coincident with the top and bottom flat portions of the modified sawtooth waveform as well as the waveform's retrace. In addition, marker pulses from the Marker Control are combined with a blanking pulse to form the Z-Axis Out blanking pulse and marker signal

4.1.5 Frequency and Sweep Control

The Frequency and Sweep Control block originates the dc level for setting the CW, CF (center), and marker frequencies. Also, this block scales the modified sawtooth waveform into the scaled sweep waveform for setting Start and Stop, and ΔF (deviation) frequencies. Signal flow within this block depends upon the selected operating mode.

4.1.6 YIG Oscillator Control

The YIG Oscillator Control block contains the circuits that directly control and drive the YIG Oscillator. A main tuning coil driver sums the OSCTUNE input with an input from the temperature control circuit to produce the YIG main tuning coil current. The OSCTUNE input from the Frequency and Sweep Control may be either a dc (CW and Ext Tune) or scaled sweep waveform (Sweep modes). The temperature control circuit monitors the temperature within the YIG oscillator and makes slight frequency corrections by vary current to the YIG main tuning coil.

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4.1.7 YIG Oscillator

The YIG Oscillator (a separate module) produces the microwave signal supplied by the instrument. Varying the current, supplied by the YIG Oscillator Control, through the main tuning coil controls the frequency of the oscillator. The FM coil allows the frequency of the oscillator to be frequency modulated (FM) by varying the current through the smaller FM coil within the oscillator. An oscillator temperature probe senses the temperature of the oscillator and provides input for a temperature compensation circuit (in the YIG Oscillator Control) which makes small frequency corrections relative to the temperature. An internal heater maintains the oscillator's YIG circuit temperature at approximately 100°C. The + Bias supplies the voltage (approximately + 13V) required for the transistor within the oscillator.

4.1.8 Marker Control

The Marker Control block stores up to three user set frequencies which can produce marker pulses in either sweep mode or CW. Each marker may be turned on or off as needed. The output pulse (MARKER) is routed to the Modulation and Leveling circuit where it is diverted to either the Attenuation control circuit (RF PIP markers) or the Waveform Generator and Z-Axis blanking for Z-Axis intensity markers.

4.1.9 Modulation and Leveling

The Modulation and Leveling block provides all the output level related controls: RF Level, amplitude modulation (AM), automatic level control (ALC) and, if installed, internal leveling. In unleveled operation, the RF level can be varied over at least a 25dB range. In the leveled operation, the RF level is limited to approximately a 7dB range or greater. The primary output from the Modulation and Leveling block is the PIN diode driving current (PIN-DIODE). Varying the diode current will change the RF output level.

Another output is the FM Coil drive current that drives a smaller FM coil in the oscillator housing, which varies the magnetic field within the oscillator and the output frequency. An external FM signal must be supplied.

4.1.10 Display

The Display block selects, scales, and displays the eight frequencies: Start, Stop, AF, Marker 1, Marker 2, Marker 3, Center, or CW. The display multiplexer, located on the Marker board, selects one of the eight inputs to the Display. A resistor network scales the input, and a voltmeter/display converts and displays the frequency.

4.2 DETAILED CIRCUIT DESCRIPTION

4.2.1 Power Supplies

4.2.1.1 ±16V Modular Power Supply

The ±16V Modular Power Supply, a potted, nonrepairable unit, is a switching-type power supply which is attached to the top cover. The cover acts as the heat sink for the supply. AC power to the supply is received through a fused connector (Corcom on the rear panel) and a line switch (S1). The switch (S1), which mounts on the rear panel, is operated by a pushrod through the front panel Balancing resistors (B189, 190, and 191; refer to schematic 0103-00-1848 sheet 5 of 5) maintain reasonable matching of the plus and minus output currents drawn from the supply and provide a minimum load for good regulation. Different models use different balancing resistors; check the parts lists for correct values. The modular power supply provides ± 16V for the Oscillator Bias, Tuning Coil Drive, and ±13V regulators.

4.2.1.2 ±13V Regulators

The ± 13V regulators are two, three-terminal regulators (VR4 and VR5) located on the rear panel (refer to schematic 0103-00-1848 sheet 2 of 5) which power most circuits within the Micro Sweep. These regulators receive their inputs from the ± 16V supplies. Resistors R8 and R9 adjust the regulator VR4 for - 13V. The diode CR2 protects VR4 if the - 16V input is shorted. Resistors R10 and R11 adjust the regulator VR5 for + 13V. The diode CR3 protects VR5 if the + 16V input is shorted.

4.2.1.3 ± 6.3V Regulators

The ± 6.3V regulators are two, three-terminal regulators (VR1 and VR2; refer to schematic 0103-00-1848 sheet 2 of 5) which power various circuits within the Micro Sweep. These regulators receive their inputs from the ± 13V supplies. Resistors R14 and R15 adjust the regulator VR2 for - 6.3V, and resistors R12 and R13 adjust the regulator VR1 for + 6.3V.

4.2.2 References

4.2.2.1 + 10V Reference

The + 10V Reference (refer to schematic 0103-00-1848 sheet 1 of 5) provides the precision reference voltages required to establish the output frequency, the display scaling, the oscillator temperature compensation, and input for the + 10 BUF reference. The temperature controlled precision reference source (U6) provides a superstable voltage output to the control amplifier (U1 pin 3). The output of control amplifier U1 is fed to the buffer

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transistor (Q1). Q1 uses the +13V supply as a source. The emitter of transistor (Q1) can be set to exactly +10V by the +10V REF ADJ potentiometer (R3), which connects to U1 pin 2. This +10V reference is the source for only the most critical circuits requiring a +10V reference. The remaining less critical circuits are supplied by the +10V Buffered supply.

4.2.2.2 + 10V Buffered

The +10V buffered supply (refer to schematic 0103-00-1848 sheet 1 of 5) provides +10V to the less critical circuits requiring a +10V supply. Operational amplifier (U2C) and transistor (Q11) form a voltage follower which is referenced to the +10VREF source. The +10V REF voltage is applied to pin 10 of the voltage follower U2C which controls the regulator transistor (Q11). The output of Q11 feeds back to the inverting input (Pin 9) of the voltage follower U2C, this maintains the +10V output within a few millivolts of the +10V reference. Thus, the buffered supply will have little voltage variation due to load current changes.

4.2.2.3 - 10V Reference

The - 10V Reference (refer to schematic 0103-00-1854) supplies - 10V to the VREF input of the marker DACs and the ΔF Offset of the Frequency and Sweep control circuits. This circuit, located on the Marker control circuit board, consists of an unity gain inverting amplifier U30B. The amplifier's gain is fixed by resistors R75 and R74.

4.2.3 Digital Control

The Digital Control (refer to schematic 0103-00-1857 sheet 1 of 2) provides the digital control lines required to control other circuits within the Micro Sweep. When a front panel pushbutton is pressed, the Digital Control decodes the input lines from the pushbuttons and enables the appropriate output line or lines. The Digital Control also lights the related front panel indicators. The Digital Control block consists of the pushbuttons and LEDs, debounce and clock circuit, programmable logic arrays with memory register outputs, and logic array for output decoding.

Within the circuit, the majority of the work is accomplished by three, factory programmed, logic arrays (U1, U2, and U3). Of these logic arrays, U1 and U2 contain output registers. These registers store the current operating state of the Micro Sweep, much the same as a computer memory. In each of these registered arrays, the input contains programmable AND and OR gates which are used to synthesize the desired logic function. The rising edge of the input clock stores the decoded input signals in the array's output registers.

Each of the logic arrays has a unique program and independent function. Array U1 is largely responsible for the "status" of the instrument's operating mode such as CW, Start/Stop sweep, etc. The outputs of this array are typically active low signals that are used to transmit the status to most of the circuits in the instrument. Two lines, MODE 1 and MODE 2, control the operating mode of Micro Sweep by selecting one of the Micro Sweep's four operating states; only three modes are of any operating value, and the fourth is used for test purposes. Table 4-1 describes the control lines.

Table 4-1.	MODE	Truth	Table

State	MODE 1	MODE 2
Display Test	0	0
Start/Stop Sweep	1	0
Delta F Sweep	0	1
CW	1	1

Logic array U2 primarily controls the markers and the display. The principal outputs of this array are the marker on/off signals: M1, M2, and M3. The second major set of outputs is the "Display Mode": DM1, DM2, and DM3. These three lines are used to indicate which of the eight possible frequencies is is being multiplexed to the display. Table 4-2 shows the truth table for the "Displayed Mode" control lines.

Displayed Frequency	DM3	DM2	DM1
Delta Frequency	0	0	0
M1	0	0	1
M2	0	1	0
M3	0	1	1
Stop Frequency	1	0	0
Start Frequency	1	0	1
Center Frequency	1	1	0
CW Frequency	1	1	1

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The third Logic Array (U3) decodes and combines the signals produced by the two registered arrays (U1 and U2). For example, it decodes the two mode lines to produce the line CWLITE which goes low when both mode lines are high. It also generates signals to drive many of the indicator LED's

4.2.3.1 Pushbuttons and LEDs

All 13 front panel pushbuttons are located on the Digital Circuit board (refer to schematic 0103-00-1857 sheet 1 of 2). One end of each switch connects through a 1kΩ pull-up resistor (R21) to VCC (+6.3V). The other end of the switch connects to an input of one of the two registered programmable arrays U1 or U2. Each input to the programmable array is pulled down to ground through a 10kΩ resistor RN2 and RN3. When a pushbutton is pressed, the input to the PAL goes from a logic 0 to a logic 1 state.

Most LEDs in the Micro Sweep are lit by pulling the cathode low. The exception is the "Lev" indicator (CR21) which is driven from the Modulation and Leveling block. Many of the LED's are integrated inside their respective switches. All switches except for the Marker On/Off toggle switch have internal LED's. The Marker indicator LED's are driven by U3 which combines information from the display mode (DM1 through DM3), marker on/off status (M1 through M3), and the blink signal. Thus, the markers can be either on, off, or blinking with either a high or low duty cycle.

4.2.3.2 Pushbutton Debounce and Clock Timing

The counter (U4) refer to schematic 0103-00-1857 sheet 1 of 2) functions as a debounce circuit for the pushbuttons. Also, the counter U4 provides two sequenced pulses which are used to store the decoded pushbutton input information into the array's output registers. This counter's outputs sequentially pulse high when the circuit is enabled and clocked. The circuit's primary inputs are the 45 kHz clock (U4 pin 14) which is generated by the display voltmeter and the ANYIN signal (U4 pin 15) which immediately goes low when any pushbutton is pressed. Outputs for the counter are the lines STATCLK (U4 pin 10), which latches data into the "status" logic array U1, and MKRCLK (U4 pin 5), which performs the same function for the ''marker'' logic array U2. Data is latched by the logic arrays U1 and U2 when their respective clocks make a low to high transition.

In the counter's quiescent state, the output (U4 pin 9) is high which feeds back to pin 13, inhibiting the count.

When any pushbutton on the front panel is pressed, ANYIN (U1 pin 12) immediately goes low. This signal connects to U4 pin 15 and resets all counter outputs on U4

to the low state. This allows the counter to begin counting. After four input clock pulses, STATCLK (U4 pin 10) goes high. This delay provides sufficient time for data stabilization and avoids pushbutton bounce. The STATCLK pulse latches the decoded data into U1's output registers. In another two clock pulses, MRKCLK (U4 pin 5) pulses high. This delay allows time for the output data from U1 to stabilize and to accommodate the data set-up requirements in U2. This second clock pulse, MRKCLK, latches data into U2's output register. In another two clock pulses, U4 pin 9 pulses high. This signal inhibits the RES input U4 pin 15 and freezes counting at that point.U4 stays in this condition until another pushbutton in depressed and ANYIN provides another high to low transition.

4.2.3.3 Registered Programmable Logic Array

Status Logic Array

Logic Array U1 primarily decodes and stores the operating status of the instrument. It receives inputs from the CW (pin 2), S/S (pin 3), and ΔF (pin 4), Ext Lev (pin 5), RF On (pin 6), Ext Trig (pin 7), and Update (pin 7) pushbuttons. The array also receives an input from U2 (ANY2) which goes high when any pushbutton attached to U2 is pressed.

The outputs of U1 control the operating mode of the instrument. Table 4-3 lists the functions of the outputs from U1.

Marker Logic Array

The marker logic array (U2) contains logic which controls the display multiplexer and the on/off status of the markers. Inputs to the array consist of marker pushbuttons M1 (pin 2), M2 (pin 3), and M3 (pin 4), and Display Start/CF (pin 7), Display Stop/AF (pin 8), and On/Off (pin 9). U2 also receives mode inputs, MODE 1 (pin 6) and MODE 2 (pin 5), from U1 and the ANYMODE signal (U2 pin 12).

The outputs of U2 consist of two, three bit control busses. The first bus is the display mode bus DM1 (pin 16), DM2 (pin 17), and DM3 (pin 18). This bus controls the display multiplexer which selects the analog frequency signal sent to the display; see table 4-2. For example, if all DM lines are a logic high, the CW frequency is routed to the display.

The second U2 control bus M1 (pin 13), M2 (pin 14), and M3 (pin 15) indicates which markers are turned on. These lines are active low if the associated marker has been turned on.

U2 also provides the output ANY2 U2 pin 19 which goes high to indicate that a U2 input pushbutton is pressed.

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Table 4-3. Status Array Functions

PIN	Name	Function
18	UPDATE	Goes low (active) when Update key is pressed. Returns high as soon as any pushbutton is pressed.
17	LEV	Toggles between high and low states when Ext Lev key is pressed. A low state indicates external leveling.
16	RFLITE	Toggles between high and low states when RF On key is pressed. A low state indicates RF is on.
15	EXTTO	Toggles between low and high when Ext Trig key is pressed. A high state indicates exter- nal trigger.
14	MODE1	Low order bit of mode command. This line changes relative to operating mode of the in- strument. Refer to table 4-1.
13	MODE2	High order bit of mode command. Refer to table 4-1.
19	ANYMODE	Goes high (active) whenever any pushbutton associated with U1 is pressed. It alerts U2 that a pushbutton has been pressed.
12	ANYIN	Goes low (active) when any front panel pushbutton is pressed.

4.2.3.4 U3, Output Decoding Logic Array

The output programmable logic array (U3) decodes four sets of inputs from the registered programmable arrays U1 and U2 to produce the following output lines: SWEEP (pin 18) is an active high when the instrument is in either Start/Stop or ΔF sweep modes, CW LITE (pin 17) is an active low when CW mode is selected, STOP DF (pin 16) is an active low when either the stop frequency or ΔF frequency is selected for display, and START CF (pin 15) is an active low when either the Start or Center frequency is selected for display. When the Ext Trig pushbutton is pressed, EXTTO (pin 7) toggles, but in CW mode the output array (U3) inhibits EXTT because external triggering in the CW mode is an illegal operation. In the sweep modes, EXTT (pin 19) is active low when external trigger is active.

U3 also provides outputs on pins 12 through 14 which control the marker status indicator LED's. U3 sums the BLINK signal at pin 1 together with the display mode (whether or not the marker is being displayed) and the marker on/off status to drive LED's CR16 through CR18. If the marker is not being displayed, the output is active low providing the associated marker has been turned on. If the marker is off, the output signal is high. If the marker is being displayed, the output is summed with the BLINK signal to result in a signal which is mostly active low if the

marker has been turned on. If the marker is not on, the inverse of the BLINK signal is summed to result in an output which is mostly high.

4.2.3.5 Blink Timer

The blink timer U27 generates the 8 Hz, 30% duty cycle pulse which blinks the Marker (M1, M2, M3) LEDs under certain conditions. The timer allows the capacitor C65 to charge to approximately + 4.2V; the current through resistor R192 and CR34 supplies the charging current. At +4.2V the timers DCHG lines goes low and the capacitor discharges through R193. The cycle repeats indefinitely.

4.2.3.6 Miscellaneous Circuits

The display scaling and offset circuit (refer to schematic 0103-00-1857 sheet 2 of 2) is included on the digital circuit board. However, it is not used with the digital circuits. Refer to paragraph 4.2.10.2 for details on this circuit.

4.2.4 Waveform Generator

The Waveform Generator (refer to schematic 0103-00-1875) produces the modified sawtooth waveform, which ultimately varies the YIG oscillator frequency. Also, it generates the blanking pulse for Z-Axis display modulation.

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Figure 4-2. Waveform Generator

4.2.4.1 Sweep Waveform Generator

The sweep waveform generator (see figure 4-2 and refer to schematic 0103-00-1875) consists of a constant current source, a comparator, waveform buffer, bottom flat clipper, and top flat clipper. The constant current source U32C U33C and U33D, controlled by the Swp Time control R21, provides the precision, high stability current that charges the timing capacitor C16. Charging the capacitor will produce the positive-going ramp. The comparator within the timer U26 detects the ramp's positive peak (about + 10.6V), toggles and discharges the timing capacitor (to about + 3.9V). The sawtooth waveform is buffered by U32A and routed to the sweep shaper. The sweep shaper clips the negative and positive peaks of the sawtooth waveform to produce the modified sawtooth waveform. This modified sawtooth waveform drives the Frequency and Sweep Control block.

Constant Current Source

The constant current source (refer to schematic 0103-00-1875) supplies the charging current for the sweep generator's timing capacitor C16. This charging current can be varied by the front panel Swp Time control (RATE CONTROL on schematic) R21.

The +10 BUF biases the base of two matched PNP transistors U33C and U33D at +10V. Also, the voltage divider R20 and the RATE RANGE potentiometer R23 divides the +10 BUFF to approximately +0.1V which is the operational amplifiers non-inverting input (U32A pin 10). The feedback loop from U32C through R18 and PNP transistor U33C attempts to control the amplifier's inverting input (U32C pin 9) to equal the reference voltage at pin 10. Therefore, the voltage at pin 9 of U32C equals the reference set by R20 and R23 and is impressed

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across the series resistors R25 and R21 (the front panel Swp Time control). The setting of R21 determines the current which flows through it, given the constant voltage across it. This current is sourced by the collector of U33C.

Both U33D and U33C are matched transistors (they share a common substrate). Their bases are connected to the + 10 V reference voltage, and their emitter circuits contain matched resisters R18 and R26. This arrangement forces the collector currents of U33D and U33C to be identical. Thus, the circuit develops a constant current, controlled by the resistance of R21, that charges the timing capacitor C16. Charging a fixed capacitor with a constant current produces a linearly increasing ramp voltage signal. See figure 4-3: TP 37. This is the source of the sweep waveform used by the Micro Sweep.

Comparator

The comparator, which is internal to the timer U36, (refer to schematic 0103-00-1875) detects the + 10.6V positive peak of the ramp by comparing the sweep signal with a + 10V reference at U26 pin 5. At the peak, it discharges the timing capacitor C16 to + 3.9V. See figure 4-3: TP 37.

As the timing capacitor is charged, the ramp generated is buffered by U32A to minimize capacitor leakage. This buffered ramp from U32A pin 1, GEN_OUT (see figure 4-3: TP37), drives one end of the voltage divider R220 and R221. The divider allows about 98% of the GEN_OUT ramp to drive the threshold THR input of the timer U26 pin 6 (see figure 4-3: Comparator Threshold). Thus, while the timer toggles at +10V, the actual waveform peaks at about 10.6V.

When the ramp at GEN_OUT reaches + 10.6V (+ 10V at U26 pin 6), the timer switches the discharge line DCHG (U26 pin 7) to ground potential. With U26 pin 7 low, the capacitor begin charging. However, zener diode CR6 limits the discharge to + 3.9V, the negative peak of the ramp. R37 controls the discharge rate. A + 10.0V voltage reference U36 sets the positive trip point (CTRL U26 pin 5) to + 10V.

In auto-trigger, the GEN_OUT ramp is also fed through the Trigger Control switch U31 to the timer's trigger input TRIG U26 pin 2. On the discharge of the GEN_OUT ramp (+10.6 to + 3.9V transition), the timer is triggered, which allows the capacitor to recharge (see figure 4-3: Comparator Trigger).

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In the External Trigger mode, the trigger control switch (U31) ac couples the timer's TRIG input U26 pin 2 to the Trig In BNC on the front panel. When the external trigger signal goes low, the falling edge initiates one cycle of the sweep sawtooth.

The timer's reset line (RESET: U26A pin 4) connects to the CWLITE control line from the Digital Control block. When either the ΔF sweep or Start/Stop Sweep mode is selected, the CW LITE is high enabling the comparator. But, if CW mode or External Tune is selected, CW LITE goes low which disables the comparator and waveform generator.

Sweep Shaper

The sweep shaper (refer to schematic 0103-00-1875) produces the modified sawtooth waveform by clipping the positive and negative peaks of the waveform generator's sawtooth waveform.

To clip the negative peak, the + 3.9 to + 10.6V (approximate) sawtooth (see figure 4-3: TP 37) from the buffer U32D drives the bottom flat clipper U35D which acts as noninverting, unity gain amplifier while the diode CR4, conducts. Diode CR4 will conduct when the sawtooth waveform is greater than + 6.2V; resistors R27, R28, and R29 bias the cathode of CR4 at approximately + 6.2V. However, below + 6.2V the loop opens up, and U35D pin 14 goes to - 13V and stays there until the level at pin 14 exceeds + 6.2V (see figure 4-3: Bottom Flat Clipper U35D pin 14). The output from the clipper U35D is a + 6V to + 10.6 (approximate) negative peak modified sawtooth waveform (see figure 4-3: Bottom Flat Clipper CR4 Cathode).

To clip the positive peak, the output from the negative peak clipper U35D drives the input to the top flat clipper (U35A) which works similar to bottom flat clipper. The top flat clipper's output TP10 SWEEPOUT is a 0 to + 10V modified sawtooth waveform (see figure 4-3: TP10).

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4.2.4.2 Blanking Pulse Generator

The blanking pulse generator (refer to schematic 0103-00-1875) creates a blanking pulse during the top flat spot, retrace, and bottom flat spot of the modified sawtooth waveform (see figure 4-4: TP 10). This generator consists four comparators. A simplified schematic of this pulse generator is shown in figure 4-5. This circuit also contains the SWEEP buffer, which drives the Sweep indicator LED, and the Z-Axis output drive circuit.

Top Flat Comparator

The top flat comparator U34C produces a + 12V pulse during the top flat portion of the modified sawtooth waveform. The comparator's inverting input (U34C pin 10) is biased at + 10V by the + 10BUFF, and the noninverting input (U34C pin 11) connects to the top flat comparator (U35A pin 1). Thus, when the output of the top flat clipper (U35A pin 1) exceeds + 10V (see figure 4-3: Top Flat Clipper U35A pin 1), the top flat comparator (U34C pin 13) toggles to + 12V. When the output of the clipper goes below + 10V, the comparator's output returns low. See figure 4-4: Top Flat Comparator.

Bottom Flat Comparator

The bottom flat comparator (U34D) produces a + 12V pulse during the bottom flat portion of the modified sweep waveform. The reference for the comparator U34D pin

9 is the CWLITE high during sweep modes (approximately + 5V) divided by resistors R93 and R97. The bottom flat comparator (U34D pin 8) toggles high when the output of the bottom flat clipper (U35D pin 14) drops below + 3V (see figure 4-4: Bottom Flat Comparator). When the output of the clipper goes above + 3V, the comparator's output returns low. The resistor divider R95 and R96 and the diode CR12 limits the comparator input to + 0.6V to keep U34D pin 8 from going negative.

Monostable Retrace Comparator

The comparator U34B, configured as a monostable, generates a blanking pulse during the sweep waveform retrace. The falling edge of the top flat comparator (see figure 4-4: Top Flat Comparator) triggers the multivibrator. The output (U34B pin 2) toggles high and about 10ms later resets low; the resistor R102 and capacitor C39 controls the time constant (see figure 4-4: Monostable Retrace Comparator).

Summing Comparator

Comparator U34A acts as an "OR" gate and sums all three blanking pulses to produce a single + 12V blanking pulse that remains high during the top flat spot, retrace, and bottom flat spot of the modified sawtooth waveform (see figure 4-4: TP9). As long as one of the three comparator output pulses remain high, the summing comparator's output remains at + 6.3V.

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SWEEP Buffer

The SWEEP buffer U35C, a noninverting unity gain buffer, (refer to schematic 0103-00-1875) drives the front panel Sweep indicator LED. When the SWEEP line is low (the ramp portion of the waveform), the Sweep indicator LED will light providing a sweep mode is selected (see figure 4-4: TP 10 and TP 9).

Z-Axis Switching and Buffer

This circuit (refer to schematic 0103-00-1875) selects the polarity of the blanking pulses and the marker pulses. The switch S1 selects the pulse polarity by switching the pulses to either the inverting (U35B pin 6) or the noninverting input (U35B pin 5) of the output amplifier U35B. For more details on selecting pulse polarity refer to paragraph 2.2.4.

4.2.5 Frequency and Sweep Control

The frequency generated by the Micro Sweep is controlled by either a dc tuning signal or a sweep waveform. The Frequency and Sweep Control block sets the dc voltage (0 to + 10V) required to set the CW, external tune, and Center Frequencies. Also, this block processes the modified sawtooth waveform from the Waveform Generator to create the scaled sweep waveform for the ΔF and Start/Stop sweep modes. In addition, the Frequency and Sweep Control block supplies the dc level used to set the markers. Figure 4-6 shows the frequency and sweep control block along with its signal flow for the various operating modes.

In internal tune CW mode (shown as a white line in figure 4-6), front panel frequency control regulates the voltage (BUF TUNE) that tunes the YIG oscillator. In external tune

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(shown as a white line in figure 4-6), the YIG oscillator is tuned by a dc or low frequency voltage at the Sweep Out/Ext Tune In. For Start/Stop Sweep (shown as a grey line in figure 4-6), the Start control and buffer along with the Stop/ΔF gain amplifier condition the modified sweep waveform which tunes the YIG oscillator. If ΔF Sweep mode is selected (shown as a black line in figure 4-6), the Stop/ΔF gain amplifier and CF buffer produce an offset modified sweep waveform which the ± clippers condition to tune the YIG oscillator.

4.2.5.1 Frequency Control and Buffer

The front panel main tuning frequency control (refer to schematic 0103-00-1848 sheet 3 of 5) produces the dc voltage (0 and + 10V) BUF TUNE (shown as a white line in figure 4-6). When internal tune is selected, the tune buffer (U10), a voltage follower, provides isolation between the main tuning potentiometer and following circuits. In internal tune, the output from the voltage follower (U10) is fed via the switch (U11) to the Ext Tune/Sweep Out connector (J6) as an output signal. In external tune, the Sweep Out/Ext Tune In (J6) drives the voltage follower's input (U10 pin 2). U10's outputs (BUF TUNE and OSCTUNE) can tune the YIG oscillator, set the center frequency (ΔF sweep mode), or set any of the three markers.

4.2.5.2 Start/Stop Sweep

The start/stop sweep circuit (refer to schematic 0103-00-1848 sheet 3 of 5 and figure 4-7), also shown as a grey line in figure 4-6, produces a scaled sweep waveform that allows the unit to sweep from a start frequency to a stop frequency. It will allow the oscillator to sweep from either a lower to a higher frequency or from a higher to a lower frequency. This block consists of the start control and buffer, and Stop/ΔF control and amplifier. Both circuits vary the peak to peak level of the modified sweep waveform. The resulting waveforms are mixed at the start/stop sweep summing amplifier (U4B).

Start Control

The sweep start circuit R195B and U4A (refer to to 0103-00-1848 sheet 3 of 5) varies the peak to peak level of the modified sweep waveform in the start/stop mode. The buffered SWEEPOUT waveform from U2A pin 1 (the 0 to + 10V modified sawtooth waveform; see figure 4-8: Sweepout) connects to one end of the START control R195B, the other end of R195B connects to + 10V (+10 BUFF). The START potentiometer varies the input level to the unity gain voltage follower U4A pin 3 between 0 and + 10V offset by + 10V dc (see figure 4-8: Start Buffer). The voltage follower U4A provides isolation between the START potentiometer and following circuits.

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Figure 4-8. Start/Stop Sweep Waveforms

With the START potentiometer R195B full ccw, the full 0 to + 10V modified sawtooth waveform drives the voltage follower (U4A). At full cw setting of the control, the buffer output is + 10V dc. And, at the center of the Start controls rotation, the output is a + 5 to + 10V scaled sweep waveform.

Stop Control

The stop circuit (see figure 4-7) R196B, U4C, and U9A varies the peak to peak level of the modified sawtooth waveform between 0 and -10V by using the STOP/ΔF con-

trol R196B to vary the gain of operational amplifier U4C between 0 and - 1. Figure 4-8 shows the output of U4C GAINOUT as the STOP control R196B is rotated from cw (0V) to ccw (full 0 to - 10V modified sawtooth waveform). The offset created by the DELTA-F OFFSET (R203, R58) is cancelled by the OFFSET CANCEL (R201, R57).

The feedback path of the amplifier U4C is controlled by the switch U9A; table 4-4 shows the control lines for the switch U9A in the Start/Stop mode.

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Control Line	Logic Level	Action	Function
S/S LITE	Low	U9A S2-D2 Closed	Connects wiper R196B to U4C pin 9 (input).
DF LITE	High	U9A S1-D1 Open	Disconnects wiper R196B from U4C pin 8 (output).

Sweep/Stop Buffer

The Start/Stop Sweep Buffer U4B, a non-inverting amplifier with a gain of + 2, sums the buffered start signal with the GAINOUT signal to produce the S/S OUT signal. The X2 gain of the amplifier U4B cancels the voltage dividing effect of the input resistors R49 and R50; the resulting maximum output waveform is 0 to + 10V. Figure 4-8: S/S Out shows the output at various Start and Stop/AF control combinations.

4.2.5.3 ∆F Sweep

The ΔF sweep circuit (refer to schematic 0103-00-1848 sheet 3 of 5 and figure 4-9) produces an offset scaled sweep waveform that allows the unit to sweep upward around the center frequency. In this mode, the center frequency can be set by the main tuning knob anywhere within the range of the Micro Sweep. The Stop/ΔF control sets the frequency deviation. Clipper circuits keep

the Micro Sweep from exceeding the limits of its frequency range. This block consists of the Stop/ΔF control R196B and amplifier U4C, the center frequency buffer U3A, and the ± clippers U3C and U3B.

∆F Control and Amplifier

In the ΔF Sweep mode, the Stop/ΔF control R196B and amplifier U4C produces an output level that can be varied between 0V dc (ΔF full ccw) and ±5V scaled sweep waveform (ΔF full cw) (as shown in figure 4-10: GAINOUT). The Stop/ΔF circuit receives its input from the buffered SWEEPOUT U2A pin 1 (the 0 to +10V modified sawtooth waveform; see figure 4-10: SWEEPOUT). The Stop/ΔF amplifier U4C sums the SWEEPOUT waveform with an offset current (-10V connected to potentiometer R203 and resistor R58) which is effectively divided by two to form a - 5V offset to the 0 to +10V sweep signal. The STOP/ΔF potentiometer R196B sets the gain of the amplifier U4C

Figure 4-9. ∆F Sweep

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Table 4-5. ∆F Logic

Control Line Logic Level Action		Action	Function
S/S LITE	High	U9A S2-D2 Opened	Disconnects the wiper R196B from U4C pin 9 (input).
DF LITE	Low	U9A S1-D1 Closed	Connects wiper R196B to U4C pin 8 (output).

between 0 and -1. When the Stop/ΔF control is full ccw, the amplifier output U4C pin 8 is OV (as shown in figure 4-10: GAINOUT). If the Stop/ΔF control is set to full cw, the amplifier output U4C pin 8 is a ±5V scaled sweep waveform (as shown in figure 4-10: GAINOUT).

The switch U9A controls the configuration of the Stop/ $\Delta$ F circuit; the lines DF LITE and S/S LITE from the Digital Control block control switch U9A (see table 4-5). The + 10V BUFF connected to resistors R201 and R57 attaches to the amplifier's output (U4C pin 8) where it has not effect on the circuit.

CF Buffer

The Center Frequency (CF) buffer U3A (refer to schematic 0103-00-1848 sheet 3 of 5 and figure 4-9), a ground referenced, inverting, unity gain amplifier, inverts the 0 (main tuning knob full ccw) to + 10V (main tuning knob full cw) BUFTUNE voltage producing a 0 to - 10V voltage (as shown in figure 4-10: CF BUFFER). This voltage is summed with the Stop/AF amplifier output U4C pin 8 at the OV Clipper amplifier U3C.

∆F Clipper

The ΔF clipper U3C and U3B (refer to schematic 0103-00-1848 sheet 3 of 5 and figure 4-9) serves two functions. It sums the center frequency voltage and the ΔF scaled sweep waveform. And, it limits the overall peaks to between 0V and + 10V, which keeps the Micro Sweep from sweeping beyond the frequency range of the instrument.

The first amplifier U3C is the summing amplifier and 0V clipper. There are two inputs to this amplifier at pin 9: the center frequency voltage summed through a 20 kΩ input resistor (R52) and the ΔF waveform summed through a 20 kΩ input resistor (R51). The two 20 kΩ input resistors and the 10 kΩ feedback resistor R55 set the closed loop gain of the amplifier U3C at - 1/2. The loop is closed as long as U3C's output U3C pin 8 is greater than + 0.6V. Above + 0.6V the diode CR8 conducts (cathode is biased to ground through the 1kΩ resistor). But below + 0.6V the diode is reversed bias, the feedback loop opens up, and the output from U3C goes to approximately - 13V. The output at the cathode of CR8 is always greater than + 0.0V.

The second amplifier U3B is the + 10V clipper. The two 100 kΩ divider resistors (R62 and R63) set the amplifier's gain at + 2, this gives the clipper circuits an overall net gain of 1. The loop is closed as long as U3B's output (pin 7) is less than + 9.6V. Above + 9.6V CR9 is reversed bias (anode is biased through a 1kΩ resistor to + 10V) opening the amplifier feedback loop which causes the amplifier's output (pin 7) to go to approximately + 13V. The output at the anode of CR8 is always less than + 10V. Figure 4-11 shows the DF OUT output TP15 for various combinations of the main tuning knob (center frequency) and the Stop/ΔF control in the ΔF Sweep mode.

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.......................................

4.2.5.4 Sweep Switching and Buffer

The switch U9B (refer to schematic 0103-00-1848 sheet 3 of 5) selects either DFOUT (ΔF waveform) or S/SOUT (Start/Stop waveform). When DFLITE goes low, switch U9B S1-D1 closes and routes the DFOUT signal to the sweep buffer (U2D). When S/S_LITE goes low, switch U9B S2-D2 closes which routes the S/SOUT to the sweep buffer U2D input. These two control lines originate in the Digital Control block. The Digital Control logic allows only one switch closed at a time.

The voltage follower (U2D) buffers the selected sweep waveform and routes the sweep waveform to the CW/SWEEP relay K2A.

4.2.5.5 Start and Stop/∆F Controls (To Displays)

The Start and Stop/ΔF controls R195A and R196A (refer to schematic 0103-00-1848 sheet 3 of 5) are mechanically linked to their respective counterparts R195B and R196B. These potentiometers supply a voltage (0 to + 10V) proportional to the setting of the potentiometers R195B and R196B which are the gain controls for the Start control and buffer U4A and the Stop/ΔF amplifier U4C. The STARTFRQ voltage is a direct input for the display multiplexer. The STOP voltage is buffered by the voltage follower U2B before being routed to the display multiplexer.

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4.2.5.9 External Tune Switches

The external tune switches (R21-S-NO and R21-S-NC; refer to schematic 0103-00-1848 sheet 3 of 5 and figure 4-12) select the External Tune mode when the Swp Time control R21 is placed in the extreme ccw position (detent).

Switch R21-S-NO is the normally open contact. When external tune is selected, this switch will close, relay K1 will energize, and the LED CR17 will light. Also, the contacts R21-S-NC will open which sends EXTUNE high. This forces logic array U1, located on the Digital Circuit board (refer to schematic 0103-00-1857 sheet 1 of 2), into the CW mode (CWI goes high).

4.2.6 YIG Oscillator Control

The YIG oscillator control block (refer to schematic 0103-00-1848 sheet 5 of 5) supplies the Transistor Bias Supply voltage and Main Tuning Coil drive current to the YIG Oscillator. In addition, it contains the temperature compensation circuit which monitors the temperature of the YIG oscillator and makes slight corrections to the frequency.

4.2.6.1 Transistor Bias Supply

The oscillator bias supply (refer to schematic 0103-00-1848 sheet 5 of 5), a three-terminal regulator VR3, supplies the + 13V required to bias the transistor in the YIG tuned oscillator. The regulator receives its input VR3 pin 3 from the + 16V modular power supply. The voltage divider R185, R186, and R187 sets the regulator's output voltage. The BIAS ADJ R187 allows fine adjustment of the bias supply.

The bias supply is turned off by interrupting the regulator feedback path by switching the relay K3A between the regulator output (VR3 pin 2) and the regulator adjustment divider string R185. Shunting off the bias supply turns off the YIG oscillator (RF Off).

4.2.6.2 YIG Main Tuning Coil

The YIG Main Tuning Coil driver (refer to schematic 0103-00-1848 sheet 5 of 5) provides the current which controls the magnetic field within the YIG oscillator. The Main Coil is the primary frequency control device within the oscillator. The YIG tuning coil driver consists of a summing amplifier U24, referenced to ground (the noninverting input to the amplifier) and two transistors Q6 and Q9 (a Darlington amplifier) which drive the main tuning coil. The amplifier U24 sums signals from the Temperature Compensation circuit (refer to paragraph 4.2.6.7), the tune offset bias (R168 and R164), and the OSCTUNE signal. The amplifier U24 drives the JFET current source Q7 which controls the output transistors O6 and O9 Zener diode CB27 maintains the output voltage of the summing amplifier within an effective range. The tuning coil draws its current from the - 16V supply through the transistor Q9 and the YIG main tuning coil, to the sense resistor (R153) and, finally, to ground. The negative voltage developed across the sense resistor R153 feeds back to the summing input of the amplifier U24. The feedback resistor R181 along with the two input resistors R177 and R178 scale the current for the different frequency bands. Resistors R164 and R168 set the tuning offset.

In the CW mode, the filter tune relay (K2B) places a capacitor (C61) in parallel with the tuning coil. This capacitor improves residual FM performance. Whenever sweep modes are used, the capacitor C61 is removed to provide quick tuning response. The resistor R182 reduces the Q of the inductive/capacitive combination by providing the dissipative element. Switch SW2-4 allows the filter to be disconnected even in the CW mode and external tune modes.

4.2.6.3 Temperature Compensation

The temperature compensation circuit monitors the temperature of the YIG oscillator housing and produces

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a signal which is summed into the YIG Main Tuning Coil circuit to make small changes in frequency to compensate for temperature. The temperature compensation circuit consist of an oscillator temperature probe, a two terminal integrated circuit transducer which attaches to the bottom of the YIG oscillator housing, and two sense amplifiers U22A and U22B. The temperature probe monitors the case temperature of the oscillator. This probe senses the temperature and conducts a current proportional to the temperature of the oscillator. The amplifiers U22A and U22B sense the current and convert it into a voltage proportional to the temperature of the oscillator. TUNE TC ADJ potentiometer R165 connected between TP30 and TP31 picks off the temperature sensitive voltage and applies it to the summing junction TP28. This temperature compensation current is summed with the TUNE OFFSET ADJUST level and the OSCIUNE at the input of the YIG Main Tuning Coil amplifier (U24).

4.2.6.4 Circuits Shown But Not Used

On the YIG Oscillator Control Circuit schematic (0103-00-1848 sheet 5 of 5), there are circuits shown, but not used in the Model 960 series Micro Sweeps. These circuits (Gunn Bias Drive, Gunn Diode Osc., Isolated Bias Supply Transistor Osc., and Supply Rectifiers Isolated Bias Supply) are used with other types of YIG oscillators. They are not currently being used in the 960 series.

4.2.7 YIG Oscillator

The heart of the Micro Sweep generators is the solid state, Yttrium-Iron-Garnet (YIG) tuned oscillator. A high-Q YIG sphere forms the passive frequency resonant element. Frequency is controlled by varying the magnetic field within the oscillator which tunes the YIG resonant frequency. The Magnetic field is controlled by varying the current through the YIG Main Tuning coil. The smaller FM coil allows the frequency to be modulated at higher rate than would be possible using the main tuning coil.

The YIG oscillator requires three inputs for operation: bias voltage, tuning current, and heater voltage. The micro sweeps use a dedicated + 13V oscillator bias supply to bias the oscillator's internal transistor. The tuning current drives the YIG main tuning coil which controls the magnetic field and oscillator frequency. The heater voltage, approximately 26V, drives the selfregulating heater maintaining the YIG sphere at a constant 100°C temperature. This elevated temperature of the YIG sphere minimizes external influences. The oscillator temperature probe monitors the oscillator's case temperature and provides an input element for the temperature compensation circuit.

In the Model 962, the PIN diode attenuator is part of the YIG oscillator. In the Models 964, 965, and 967, the PIN diode attenuator is external to the YIG oscillator. However, the PIN diodes are all controlled by the PIN Diode Driver (refer to paragraph 4.2.9.2). The attenuator is a dual diode reflective type attenuator which is adjustable over a 0 to 25 dB range. The PIN diodes (refer to schematic 0103-00-1848 sheet 4 of 5) shunt a 50Ω strip transmission line; as the diode current increases shunt resistance decreases, reducing the power level at the attenuator output.

4.2.8 Marker Control

The marker control (refer to schematic 0103-00-1854) stores up to three marker frequencies and produces a pulse as the sweep frequency, SWEEPBUF, sweeps past the the marker frequency. The marker frequency is stored by first converting an analog voltage proportional to the marker frequency into a 10-bit digital word. Then, this 10-bit word is stored in one of three latching DAC's. The DAC reconverts the digital word back into an analog voltage which drives the positive input of a comparator. As the modified sawtooth waveform (connected to the comparator switches from high to low. The transition is differentiated and converted into a pulse by an output comparator.

4.2.8.1 Marker Analog To Digital Converter

The Marker Analog to Digital (A to D) converter U12 (refer to schematic 0103-00-1854) transforms an analog voltage (0 to + 10V), proportional to the marker frequency as set by the main tuning knob, into a 10 bit digital word. The analog voltage (BUF__TUNE), scaled by resistors R69 and R70, drives the A to D convertor's VIN + input U12 pin 6. This input voltage VIN + to the A to D is 50% (0 to + 5V) of the BUF TUNE voltage. The MARKER ZERO POINT ADJUST potentiometer R216 offsets the A to D the VIN – input (U12 pin 7). The reference to the A to D (U12 pin 9) is + 2.5V (derived from the + 10V Buff supply) which can be adjusted by potentiometer R76. This effectively sets the gain of the A to D.

To initiate the conversion process, the circuit U15E and U15D provide a pulse to force an initial conversion in the A to D converter. When the MKRSET control line goes low which is generated by the front panel Update pushbutton, the high to low transition of MKRSET is differentiated by capacitor C29 and routed through the two inverters (U15D and U15E) to the WR and INTR inputs of the A to D forcing an initial conversion. As long as the MKRSET remains low, the A to D continually converts the analog signal to a 10-bit digital word. This allows the marker frequency to be continuously changed.

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While the MKRSET line U12 pin 1 is low, the A to D converter will continuously convert the marker control voltage BUFFTUNE into 10 bit digital words. If any pushbutton is pressed, MRKSET returns high and the last conversion is memorized.

The A to D also supplies the A to D clock (ADCLOCK) U12 pin 23 to the D to A converters. The resistor R68 and capacitor C28 set the time constant for the clock. There is no timing relationship between A to D and the D to A converters.

4.2.8.2 Marker Digital To Analog Converter

The Marker Digital to Analog Converters U14, U16, and U17 (refer to schematic 0103-00-1854) change the 10 bit digital word back into a 0 to + 10V analog voltage. The converter consists of two parts: the D to A which converts the digitized word into a current and an operational amplifier which transforms the current into a voltage. There are three D to A converters and amplifiers, one for each marker.

Using Marker 3's D to A converter U14 as an example, the converter must first be selected by setting the control line M3D (U14 pins 1 and 4) low. Pushing the Update pushbutton causes MKRSET (U14 pin 2) to go low which loads the 10 bit digital word generated by the A to D converter (U12) into the converter. The ADCLOCK from the A to D converter (U12) clocks the two input registers within the A to D converter. When MKRSET returns high, the data is permanently latched in the D to A. The reference for the D to A is supplied by the – 10V REF. The other two D to A converters operate the same as the converter U14.

The D to A converter produces a differential output current at U14 pins 11 and 12. These currents drive the operation amplifier U30A which produces a voltage proportional to the amplifier's input current. Thus, the D to A reproduces the voltage digitized by the A to D.

The marker enable decoder (U28) selects the D to A converter to be updated; see table 4-2. The three inputs (DM1, DM2, DM3) to the decoder, which originate in the Digital Control block, select which of the three output lines (M3D: pin 12, M2D: pin 13, M1D: pin 14) will be enabled (only three of the eight lines are used). The decoder is permanently enabled by hardwiring E1 (pin 4) and E2 (pin 5) to ground, and E3 U28 pin 6 to + 6.3V.

4.2.8.3 Marker Output Comparator

The marker output comparator (refer to schematic 0103-00-1854) produces the high to low transition that is converted into marker pulse. Each of the three markers has its own output comparator. Only the comparator for marker 3 will be described, the other two operate the same. The non-inverting input to the comparator (U30A

pin 1) is the output voltage from the A to D circuit. The inverting input of the comparator U29C pin 10 connects to the SWEEPBUF input (J15 pin 1). The SWEEPBUF voltage can be either the 0 to 10V scaled sweep waveform (set by the frequency control block) or the dc tuning voltage.

When the SWEEPBUF voltage is lower than the marker voltage, the comparator's output is high. As the SWEEPBUF voltage passes the marker voltage, the comparator's output (U29C pin 13) switches low. The comparator resets at the sweep retrace.

The output of the comparator is enabled or disabled by pulling the comparator output high or low respectively (the comparator has an open collector output). Each output comparator has an inverter connected to its output. When a marker (M1, M2, and M3) is turned on, the line M1, M2, and M3 goes low and the inverter's output (U15B, U15A, and U15F) goes high, enabling the comparators. The comparators are disabled (pulled low) when a marker is not turned on (M1, M2, and M3 remains high).

4.2.8.4 Transition Detector

The output comparator's high to low transition is capacitively coupled to the marker duration comparator (U29B; refer to schematic 0103-00-1854). The + input to the comparator (U29B pin 7) is biased between + 4 and + 5.7V; this voltage is set by the MARKER DURA-TION control (R213). As the differentiated marker pulse (U29B pin 6) passes through the level set by the marker duration bias voltage, the marker duration comparator produces a positive pulse at U29B pin 1. Varying the bias voltage moves the comparator's trip point up or down on the differentiated input marker pulse, thus varying the MARKER pulse width.

4.2.8.5 Display Multiplexer

The display multiplexer (refer to schematic 0103-00-1854) is shown on this schematic because many of the inputs and control line are also associated with the Marker Control block. For details about the display multiplexer, refer to paragraph 4.2.10.1.

4.2.9 Modulation And Leveling

The Micro Sweeps use a PIN diode attenuator to vary the RF output level. The circuits in the modulation and leveling block control the PIN diode's current, and consequently, the RF output level. There are several ways of varying the output level: the front panel RF Level control, the front panel AM In, ALC In (external leveling), or optional internal leveling. Figure 4-13 shows the relationship of the circuits within the Modulation and Leveling block.

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Figure 4-13. Modulation and Leveling

4.2.9.1 Level Input Amplifier

The level input amplifier U25D (refer to schematic 0103-00-1848 sheet 4 of 5) sums the inputs from the RF Level control, AM Input, and an offset bias (R129 and R130). When the micro sweep is being leveled, additional signals are supplied by the automatic leveling control circuit. The resistor network (R114, R1, R115, and R116) supplies a 0 to + 4Vdc signal as the wiper of the front panel RF Level control R1 is rotated clockwise. This network gives the potentiometer a taper which allows a fairly linear control of attenuation (in dB) over the single turn of the RF Level control. This RF Level voltage is scaled by the level input amplifier U25D to a nominal - 1.8V to 0Vdc signal at TP23 (ATTEN DRV).

The external AM input (AM In) can be summed with the RF Level voltage at the summing junction (pin 13) of the summing amplifier U25D. An input of 0 to - 10V peak will be sufficient level to fully amplitude modulate the RF output. Amplitude modulation follows a logarithmic relationship to the drive voltage over the 0 to - 10V range. Positive AM inputs are shunted to ground via the diode CR19 and have minimal effects on the RF output level.

Another inverter (U25A) can be added to invert the attenuation level when cathode grounded PIN diodes are used. This inverter can be selected by removing jumper W5 and installing jumper W6.

4.2.9.2 PIN Diode Attenuator Driver

The PIN diode attenuator driver U19 (refer to schematic 0103-00-1848 sheet 4 of 5) converts the ATN__DRV signal into the PIN diode drive current. Also, intensity markers can be summed with the driver input for RF PIP modulation. Switches SW2-2 and SW2-3 select the PIP markers, and the front panel access potentiometer (R224) sets the marker size. The driver delivers a nominal 6mA drive current per input volt to the PIN diode. The maximum current required for maximum attenuation is approximately 20mA (40mA for the Model 962).

4.2.9.3 Automatic Level Control

Automatic level control (ALC) maintains a flat output level over the Micro Sweep's frequency band. The circuit is the control portion of an automatic leveling loop (refer to schematic 0103-00-1848 sheet 4 of 5 and figure 4-14). To complete the loop, either an external negative detector must be used (refer to paragraph 3.2.6) or the internal leveling option (Option 001) must be installed. With either external or internal leveling, the RF level control range is limited to approximately 7dB. The ALC circuit consists of the input switching U20, leveling amplifier U18, leveling comparator U25B, and leveling amplitude control circuit U5 and Q3.

The input switching U20 selects either the external ALC In or internal leveling (Option 001). When the Ext Lev

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pushbutton is pressed, the LEV line goes low, closing S2-D2 (opening S1-D1) and connecting the ALC In to the leveling amplifier (U18). The internal leveler (option 001) supplies the input to the amplifier when LEV is high (S1-D1 closed, S2-D2 opened).

The input amplifier (U18) provides both the gain necessary to drive the comparator U25B and an input to the level input amplifier U25D. Without a leveling input signal, the amplifier output U18 pin 6 sets at 0V; the LEVL ZERO potentiometer (R124) adjust the level to 0.0V. With a leveling input signal, the amplifier output sets at about – 6.4V. The gain of the amplifier can be varied by adjusting the front panel LEVELING LOOP GAIN potentiometer control (R131). Setting the amplifier gain affects the amplifier's output voltage.

The leveling comparator (U25B) detects when adequate leveling signal is supplied by the leveling amplifier (U18). Without an ALC input, the comparator output (U25B pin 7) is - 10V. And with an adequate ALC input level, the

comparator output (U25D pin 7) is + 10V. The comparator has a reference level set at - 32mV (resistors R139 and R136) and employs positive feedback (resistors R140, R139, and R136) giving ± 3mV hysteresis.

The Leveling amplitude controlcircuit (see figure 4-14) controls the leveling input bias to the level input amplifier (U25D). When unleveled, the comparator U25B biases the input to the diode string at - 10V, which causes the diode (U5 1-2) to conduct. This places point A (figure 4-14)at - 0.6V, clamps point B (figure 4-14) at 0V, and reverse biases diode (U5 7-8). The level dc offset is 0V, "cancelling" the level output of 0V, and the RF level potentiometer has full control of the RF output level.

When leveling is selected and adequate ALC input is received, the comparator U25B switches to + 10V. This forward biases Diode U57-8. The transistor Q3 and diode string CR21 U5 pins 11, 12, 7, 8, 6, and 5 conduct, and the diode U5 pins 1 and 2 is revered biased. The level

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at point B, determined by the setting of the RF Level control R1, can be varied between + 2.4V (RF Level: full ccw) and + 6.4V (RF Level: full cw). This signal offsets the dc signal in the leveling input and sets the RF Level potentiometer to operate over a more limited range required by the dynamics of the leveling feedback loop.

4.2.9.4 FM Coil Drive

The FM coil driver U21 (refer to schematic 0103-00-1848 sheet 4 of 5) converts the external FM In signal into the FM coil drive current. The FM coil is a small secondary coil within the YIG oscillator which is designed for more rapid tuning than the YIG main tuning coil. Varying the current through the FM coil slightly alters the magnetic field within the YIG oscillator, thus varying the frequency of the oscillator. The driver U21 is configured as a dc coupled, inverting, unity gain power amplifier, with the FM coil and the resistor R150 comprising the feedback path.

4.2.10 Digital Display

The display block (see figure 4-15) selects, scales, and displays the eight frequencies: Start, Stop, ΔF, Marker 1, Marker 2, Marker 3, Center, or CW. One of the eight

inputs to the analog multiplexer (located on the Marker board; refer to schematic 0103-00-1854) is selected and routed to the offset and gain network (refer to schematic 0103-00-1857 sheet 2 of 2). The offset and gain network scales the dc voltage for the voltmeter IC (refer to schematic 0103-00-1857 sheet 1 of 2). The voltmeter IC directly drives the frequency display.

4.2.10.1 Display Analog Multiplexer

The display multiplexer U13, located on the Marker board (refer to schematic 0103-00-1854), selects one of eight analog voltages (0 to + 10V proportional to the respective frequency) to be displayed: the ΔF frequency, the three marker frequencies, the Stop frequency, the Start frequency, the Center Frequency, and the CW frequency.

Each of the multiplexer's inputs (U13 pins 4, 5, 6, 7, 9, 10, 11, 12) connects its respective analog frequency voltage directly to its respective source with the exception of the ΔF voltage which must be offset for the display. The three DM control lines (DM1: U13 pin 1, DM2: U13 pin 16, and DM3: U13 pin 15) from the Digital Control circuit are decoded by the multiplexer (refer to table 4-6) and selects the analog voltage (DISPLAY) routed to the Offset and Gain Network.

Figure 4-15. Display

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Table 4-6. Display Multiplexer Truth Table

Displayed Frequency	Lo	ocation	DM3 A2 U13-15	DM2 A1 U13-16	DM1 A0 U13-1
ΔF	S1	U13-4	0	0	0
M1	S2	U13-5	0	0	1
M2	S 3	U13-6	0	1	0
МЗ	S4	U13-7	0	1	1
STOP	S5	U13-12	1	0	0
START	S6	U13-11	1	0	1
CENTER (CF)	S7	U13-10	1	1	0
CW	S8	U13-9	1	1	1

4.2.10.2 Offset and Gain Network

The offset and gain network (refer to schematic 0103-00-1857 sheet 2 of 2) scales and offsets the input

voltage DISPLAY from the display analog multiplexer U13 (refer to schematic 0103-00-1854) for the digital display voltmeter U5 (refer to schematic 0103-00-1851). The resistors (R9, R10, R11, R12, R13, R15, R17, R14, and R16) comprise this circuit. Potentiometer R13 sets the high end of the Micro Sweep's frequency band and potentiometer R14 sets the low end of the Micro Sweep's frequency band. The + 10V Reference provides a stable reference level for this network.

4.2.10.3 Voltmeter and Display

The voltmeter (U5) converts an analog voltage proportional to the selected frequency and enables the appropriate segments on the 3 digit LCD display U6 (refer to schematic 0103-00-1851).

The voltmeter (U5) is a analog to digital converter (A to D) with a built in LCD display driver which functions as a voltmeter. The voltmeter is powered by ± 6V supplies; these supplies originate with the ± 13V supplies and use the drop of the two zener diodes (CR1 and CR2). The resistor (R7) and capacitor (C3) set the voltmeter's oscillator at 45 kHz; the 45 kHz is also used as the clock for the Digital Control block (refer to paragraph 4.2.7.2). The two capacitors (C4 and C5) and the resistor (R8) are the integrator for the voltmeter. The transistor (Q1), an inverter, drives the decimal point out of phase with the back plane; thus, the decimal point is always displayed. The 24 lines from the voltmeter directly drive the segments of the LCD display.

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5.1 FACTORY REPAIR

Wavetek maintains a Customer Service department for those customers not possessing the necessary personnel or test equipment to maintain their instrument. If an instrument is returned to Wavetek for service, a detailed description of any malfunction should be attached to minimize turn-around time.

5.2 EQUIPMENT REQUIREMENTS

Calibration test equipment, minimum specifications and suggested models are given in table 5-1.

NOTE

Minimum specifications are the principal parameters required for performance of the calibration, and are included to assist in the selection of alternate equipment, which may be used at the discretion of the using laboratory. Satisfactory performance of alternate items shall be verified prior to use. All applicable equipment must bear evidence of current calibration.

Instrument	Minimum Specifications	Suggested Manufacturer/Model
Oscilloscope	Sensitivity: 5mV/div. Rise/Fall time: <0.05 μs. Sweep rate: 50 ms to 5μs/div. Trigger: Int and Line. Other: XY inputs.	Tektronix 2465 Tektronix 453 Tektronix 475
Spectrum Analyzer	Range: 1 to 18 GHz Freq/Division: 10 kHz/div Bandwidth: 3kHz	Tektronix 492 HP 8559 HP 141T
Frequency Counter	Range: 5Hz to 10 kHz and 1 to 18 GHz. Phase Locking.	EIP 578
RF Power Meter	Response: 1 to 18 GHz Range: +20 to -40 dBm Readout: dBm and dBref.	HP 436A with HP 8484A Power Sensor. Wavetek Microwave 8501.
Digital Voltmeter	Range: 19 mV to 19V full scale. Resolution: 4½ digits Accuracy:½ LSB.	Fluke 8600A Fluke 8050A
DC Voltage Source	0.0 to +15V dc.	Fluke 332B Datel Model DCV-8500

Table 5-1. Calibration Test Equipment

Page 68

Instrument	Minimum Specifications	Suggested Manufacturer/Model
Directional Coupler	Range: 1 to 18 GHz Coupling: – 16 dB	Krytar 1820 Narda 3292-1
Crystal Detector	HP 8470B Option 012.
RF Attenuators	3dB with Type N connectors, 1 to 18 GHz.	HP 8491B Option 003.
	10 dB with Type N connectors, 1 to	HP 8491B Option 010.
	40 dB with Type N connectors, 1 to 18 GHz.	HP 8491B Option 040.
Coaxial Adapters	BNC Tee	Pomona Model 3285, Tektronix 103-0030-00
Coaxial Cables	50Ω BNC(M) to BNC(M). 50Ω BNC(M) to Type N (M).
Scope Probe	Direct Probe (X1).	Tektronix P6028, Tektronix P6101.
Network Scalar Analyzer		Wavetek Models 1038-N10 or 1038-NS20

Table 5-1. Calibration Test Equipment (Continued)

5.3 PRELIMINARY SETUP PROCEDURES

WARNING

Calibration sequences require power On with the instrument covers removed. This should be done only by qualified personnel aware of the electrical hazards.

1. Verify that all power switches are off, and set all calibration test equipment controls as necessary to avoid damage to the equipment and that dangerous voltages will not be present on output terminals when the power switches are turned on.
2. Remove the Micro Sweep instrument top cover while being careful not to damage the modular power supply wiring on the top cover. The top cover with the modular power supply will have to be supported in order to relieve tension on the interconnecting cables.

3. Set SW2 on the main board as follows:
- 1 Closed
- 2 Open
- 3 Closed
- 4 Closed
- 5 Closed

Set SW1 on the Waveform Generator board as follows:

1 Closed
2 Closed
3 Open
4 Open
5 Closed
4. Connect the calibration test equipment and the Micro Sweep to the appropriate power source.
5. Do not change the setting of any Micro Sweep control or switch unless specifically instructed to do so. Each following step depends on the setting from the preceding step.

Page 69

6. Turn the Micro Sweep and all calibration test equipment power switches on, and allow sufficient warm-up time for the equipment (the Micro Sweep requires 15 minutes warm-up time).
7. All of the test points (TP) and adjustments used in the Micro Sweep calibration procedure are located on the main, Marker, and Waveform Generator boards are shown in figure s 5-1, 5-2, and 5-3.

NOTE

Due to the interaction between adjustments, calibration of the instrument should be performed in the exact sequence presented in the calibration procedure.

5.4 CALIBRATION

Table 5-2 contains the calibration procedures that cover routine adjustment of the Model 960 Micro Sweep at specified service intervals. Initially, 6 month intervals are recommended; however, actual experience within the user's environment may allow greater intervals.

The completion of these calibration procedures returns the instrument to correct calibration. All limits and tolerances given in these procedures are calibration guides and should not be interpreted as instrument

specifications. Instrument specifications are given in Section 1 of this manual.

These procedures do not cover adjustments of the oscillator temperature compensation circuit (R165, R154, and R161) because these adjustments require specialized test and measurement equipment. These adjustment points have been painted over at the factory to maintain original factory settings and should need adjustment only as a result of catastrophic instrument failure. In this event, please refer the instrument to Wavetek's Customer Service department for factory calibration service.

After completing the calibration procedure, place SW2 in the following conditions:

SW2-1 Closed SW2-2 Opened SW2-3 Closed SW2-4 Closed SW2-5 Closed

Finally, verify that SW1 is set to the following conditions:

SW1-1 Closed SW1-2 Closed SW1-3 Opened SW1-4 Opened SW1-5 Closed

				Measurement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
1	Verify Power Supply A Start: Full ccw Stop/AF: Full cw Swp Time: Full cw RF Level: Full cw	Mode: CW M1: Off M2: Off	TP3 TP39 (Ground)	None	- 16.2V	±05V <100 mVp-p Line	Use DVM to measure volt- age levels and oscilloscope to check 60 Hz line noise spikes
2		Ext Trig: Off Ext Level: Off RF On: On	TP6		+ 16.2V	±0.5V <100 mVp-p Line
3				TP4		— 13.0V	± 0.5V <200 mVp-p Spike	Use DVM to measure volt- age levels and
4				ТР7		+ 13.0V	±0.5V <200 mVp-p Spike	check 44 kHz noise spikes.
5				TP5		- 6.3V	± 0.2V <400 mVp-p Spike
6				TP8		+ 6.3V	± 0.2V <400 mVp-p Spike

Table 5-2. Calibration Procedure

Page 70

Table 5-2.	Calibration	Procedure	(Continued)

				Measurement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
7	Set +10 V Reference	Main Tuning: Full cw Start: Full ccw Stop/ΔF: Full cw	Mode: CW M1: Off M2: Off	TP1	R3	+ 10.000V	± 1 mV <1 mVp-p Noise	Check 60 Hz line noise in steps 7 and 8.
8	Verify + 10V Buff	Swp Time: Full cw RF Level. Full cw	M3: Off Ext Trig: Off RF On: On	TP2	None	+ 10.000V	± 10 mV <1 mVp-p Noise
9	Set Display Zero Point	Main Tuning: Full ccw		Micro Swp Display	R13 Digital Control	0 00 GHz	Exactly	Observe Micro Sweep display and set R13 as close as possi- ble to polarity close point.
10	Set Display Range	Main Tuning: Full cw			R14 Digital Control	Model 96 Model 96 Model 96 Model 96	2: 3.10 GHz 4: 4.80 GHz 5: 5.50 GHz 7: 6.10 GHz	Observe Micro Sweep display and set R14 for the exact value specified.
11	Set Display Offset				R13 Digital Control	Model 96 Model 96 Model 96 Model 96	2: 4.08 GHz 4: 8.45 GHz 5: 12.45 GHz 7: 18.05 GHz	Observe Micro Sweep display and set R13 for the exact value specified.
12	Verify Display Offset				None	Model 96 Model 96 Model 96 Model 96	2: 0.95 GHz 4: 3.65 GHz 5: 6.95 GHz 7: 11.95 GHz	Observe Micro Sweep display and verify that reading is with- in ± 1 LSD of specified value.
13	Set Δ F Minimum Deviation	Stop/∆F: Full ccw	Mode: ΔF Swp Display Stop/ ΔF: On.		R89 Marker	0.01 GHz	Exactly	Observe Micro Sweep display and set R89 for specified dis- play reading.
14	Set ΔF Maximum Deviation	Stop/∆F: Full cw			R88 Marker	Model 96 Model 96 Model 96 Model 96	2: 3.10 GHz 4: 4.80 GHz 5: 5.50 GHz 7: 6.10 GHz	Observe Micro Sweep display and set R88 to read the differ- ence beteen high and low end frequen- cies. For example, (962) 4.05-0.95 = 3.10 GHz.
15		Stop/∆F: Full ccw			None	0.01 GHz	Exactly	Repeat steps 12, 14, and 15 until readings fall within the specified value.

Page 71

				Measurement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
16	Verify Sweep Waveform	Swp Time: Full cw	Mode: S/S Swp	TP10 (Sweep Out) Wave- form	None	See F	igure 5-5.	Use oscillo- scope and verify sweep waveform.
17	Set Positive Peak				R220	3 ms See F	flat spot igure 5-5.	Use oscillo- scope and set positive peak (+10V) (Chan 1) flat spot to 3 ms. This set- ting is not critical.
18	Set Negative Peak				R28	– 10 mV	± 10 mV	Use oscillo- scope and set negative peak to - 10 mV It is important to set the peak as close to - 10 mV as possible.
19	Set Minimum Sweep Time				R23	18 ms	+ 1/ – 2 ms	Use oscillo- scope and set rising portion of modified sawtooth wave. See figure 5-5.
20	Verify Maximum Sweep Time	Swp Time: Full ccw (But not to Ext Tune)			None	≥20 s		Use oscillo- scope to verify rising portion of modified sawtooth is greater than 20 s. See figure 5-5.
21	Verify WF Generator Blanking	Swp Time: Full cw		TP11	None	+ 2.5	5V (min)	Use oscillo- scope to verify blanking pulse at TP11. SW1-2 and SW1-5 closed; rest open.
22	Verify Sweep Indicator							Observe Micro Sweep's sweep indic- ator blinks.
23	Set Negative Peak at Blanking Pulse				R210	0.0V	± 20 mV	Use oscillo- scope and set bottom of blanking pulse. See figure 5-5.

Page 72

				Measurement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
24	Verify Z-Axis Output	Swp Time: Full cw	Mode: S/S Swp	Z-Axis Out- put BNC	R210	0.0V	± 20 mV	Use oscillo- scope to verify blanking pulse is present at Z- axis out (Rear Panel).
25	Verify External Trigger		Ext Trig. On		None			Observe Micro Sweep's sweep indica- tor stops blinking.
26	Verify External Trigger			Sweep Indicator				Short center conductor of Trig In BNC to ground. Observe Micro Sweep's sweep indica- tor indicates a sweep.
27	Set Sweep Control Gain		Power: Off					Turn power off Remove Wave form Generato Board.
28	-							Connect dc voltage stan- dard to TP38
29			Power: On Mode: ΔF Swp					Turn power on. Wait 3 minutes for Micro Sweep to stabilize.
30		Stop/∆F: Full cw						Connect a short between TP18 ( - 10V ref) and TP29 (gnd 2).
31								Set dc voltage standard to + 10.000V; measure with DVM and note reading.
32				TP13 (Gain Out)	R202	- 10.000V	± 10 mV	Connect DVM to TP13 and adjust R202 fo reading.

Page 73

				Measurement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
33	Set ∆F Offset Offset	Stop/ΔF: Full cw	Power. On Mode: ΔF Swp	TP13	R203	0.00V	± 10 mV	Set dc voltage standard for + 5.000V.
								Remove the short betweer TP18 and TP29.
								Use DVM to set ∆F Sweep offset
34	Set S/S Sweep Off- set Cancella- tion	Stop/∆F: Full ccw	Mode: S/S Swp		R201	0.00V	± 10 mV	Set dc voltage standard for 0 000V
35	Verify Sweep Circuit Performance		Power: Off		None			Turn power of and replace Waveform Generator Board Discor nect voltage standard
36		Swp Time: Full cw Start: Full ccw Stop/∆F: Full cw	Power: On Mode: S/S Swp RF On: On	TP16				Connect oscilloscope t TP16. Verify oscillo- scope display modified sweep wave- form. See figure 5-5.
37		Start: Full cw Stop/∆F: Full ccw				See Comments		Verify oscillo- scope display inverted modified waveform. Se figure 5-6
38		Main Tuning: 2.500 for 962 6.050 for 964 9.700 for 965 15.000 for 967 Stop/ΔF: Full cw	Mode: ∆F Swp					Verify oscillo- scope display modified sweep wave- form
39		Stop/∆F: Gradually rotate to full ccw				+ 5.00V (at full ccw)	± 50 mV	Verify oscillo- scope display modified
40		Stop/∆F: Full cw						sweep wave- form that approaches a flat trace (full ccw).

Page 74

				Measurement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
41	Verify Sweep Circuit Performance	Main Tuning: Full ccw	Mode: ∆F	TP16	R201	0.0V	± 50 mV	Verify oscillo- scope displays negative peak of waveform does not go below 0 0V.
42		Main Tuning: Full cw			None	+ 10.00V	± 200 mV	Verify on oscilloscope positive peak of waveform does not exceed + 10V.
43			Display Start/ CF	Micro Sweep Display		Model 962 Model 964 Model 965 Model 967	2: 4.050 GHz 1: 8.450 GHz : 12.450 GHz : 18.050 GHz	Verify Micro Sweep's dis- play reads specified value.
44			Display Stop/ ∆F			Model 96 Model 96 Model 96 Model 96	2: 3 10 GHz 4: 4.80 GHz 5: 5.50 GHz 7: 6 10 GHz	Verify Micro Sweep's dis- play reads specified value.
45	Set Marker Zero		Mode: CW					Connect a jumper be- tween E10 (left side FP Swp Time control) and ground
46								Connect dc voltage stan- dard to Ext Tune In BNC. Set the dc standard to + 5.0 mV.
47			M1: Press					Micro Sweep front panel. M1 flashes at low duty cycle (mostly off).
48			On/Off: Press once Update			0.950 Gi 3.650 Gi 6.950 Gi 11.950 G	Hz for 962 Hz for 964 Hz for 965 Hz for 967	Micro Sweep front panel M1 flashes at high duty cycle (mostly on). M1 Swp display reads close to specified value. Mkr LED indicator lit.

Page 75

				Measurement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
49	Verify Marker Pulse Level	Main Tuning: Full cw	Update Press	TP21 (M1 Out) Marker	None	See Comments		Connect oscilloscope to TP21
								Scope settings Coupling: dc Sens: 10 mV/ Div.
								Verify oscillo- scope close up dc level at specified value
50	Set Noise Transition				R216			Use oscillo- scope to set for a noise transtion from 0 to + 10 0 mV as R216 is rotated.
51					None			Set dc voltage standard to 0 00 V. Note frequency shown on this Micro Sweep display.
52			Mode: CW			Set to reading in step 51	± 1 digit	Verify Micro Sweep display shows some reading as in step 50 ± 1 digit
53								Disconnect jumper be- tween E10 and ground, Dis- connect volt- age standard.
54	Set Marker Tracking	Main Tuning: Full cw minus ¼ turn.		Display				Note exact reading on display
55			M1: Press Update: Press		R76	See Comments		Adjust to exactly equal to reading in step 54
56		Main Tuning: Center of Frequency Band.			None			Note exact reading on display

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				Measurement			an da anna an an tha dhannan ann an tha dha an t
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
57	Set Marker Tracking	Main Tuning: Center of frequency band.	Mode: CW	Display	None	See Comments		Verify reading is same as step 56 ± 2 digit
58	Set Marker Pulse Width	Start: Full ccw. Stop: Full cw.	Mode: S/S Swp	Display and Oscillo- scope
59		Main Tuning: Set near low frequency of band.
60		Main Tuning: Set near center frequency of band	M2: Press On/Off: Press Update: Press
61		Main Tuning: Set near near high frequency	M3: Press On/Off: Press Update: Press
62				Swp Out. Co	nnect scop	e Channel 1 to	Swp Out, Trigge	r on Channel 1.
63				TP22. Conne needed.	ct scope C	hannel 2 to TP	22. Adjust scope	sweep as
64					R213 Ad pulse hig Adjust R2 ± 50µs p	just for three v n + 4.5V minin 13 for a 100µs pulse.	isible pulses on ( num and low of 0	Channel 2. Verify 3V maximum.
65	Set Zero Level	Main Tuning. Set to center of frequency band.	Mode: CW M1: Press On/Off: Press once M2: Press On/Off: Press once M3: Press On/Off. Press once Ext Lev: Off (LED off) Lev LED: Off.	TP24	R124	0.000V	± 2 mV	Connect dc voltmeter to TP24. Places unit in unleveled operation
66	Set Full Output			TP23	R130	0.000V	± 2 mV	Connect dc voltmeter to TP23.

5-10

Page 77

				Measurement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
67	RF Output Power	Main Tuning: Rotate from full ccw position to full cw position.		RF Output	None	12 dBm	(Minimum)	Connect micro- wave power meter as shown in figure 5-7. Some micro sweeps have 70 mW of output power; use fixed pads as necessary.
68	Set Maximum Attenuation	Main Tuning: Set to center of frequency band.				See Comments		Note RF output level
69		RF Level: Full ccw			R112	35 dB	± 7 dB	Set R112 for 35 dB less than reading in step 68.
70		RF Level: Rotate full cw and back to full ccw.			None			Verify level range is 35 ± 7 dB
71	Verify External Control	RF level: Full cw						Connect + 10.0 Vdc supply to AM In Verify out- put level is - 35 ± 7 dBm.
72	Set Leveling Circuit	Ext Level: On (See comments)			R128	+ 10 dBm	± 0.5 dBm	Connect equip- ment as shown in figure 5-8 If Internal Level- ing Option (001) is installed, leave Ext Level off.
73		Start: Full ccw Stop/ΔF: Full cw Swp Time: Mid-range	Mode: S/S Swp			+ 10 dBm	± 0 1 dBm	Set R128 for + 10 ± 0.1 dBm at lowest point on fre- quency band
74					None	Flat ± (Externa Flat ± (Interna	0 8 dBm Illy leveled) 0.9 dBm Ily leveled)	Verify flat response.

Page 78

					Mea	surement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
75	Setting Frequency	Main Tuning: Full ccw	Mode: CW	RF Output	R168	Mod 1.0 GHz : Mod 3.7 GHz : Mod 7.0 GHz : 12.0 GHz :	el 962: ± 0.001 GHz el 964: ± 0.001 GHz el 965: ± 0.001 GHz el 967: ± 0.001 GHz	Connect as shown in figure 5-9. Caution: Some Micro Sweeps may have output level of + 18 dBm. Do not exceed input power to fre- quency counter. Adjust R168 for low frequency reading.
76		Main Tuning: Full cw			R177	Mod 4.0 ± 0 Mod 8.4 ± 0 Mod 12.4 ± Mod 18.0 ±	el 962: ) 001 GHz el 964: ).001 GHz el 965: 0.001 GHz el 967: 0.001 GHz	Adjust R177 for high frequency reading
77	Verify Sweep Output	Start. Full ccw Stop/ΔF: Full cw Swp Time: Full cw	Mode. S/S Swp	Sweep Out/Ext Tune In	None	See Comments		Verify 0 to + 10.0 ± 0.02V modified saw- tooth wave- form at Sweep Out. Connect oscilloscope to Sweep Out BNC.
78	Verify Z-Axis Output			Z-Axis Out				Connect oscilloscope to Z-Axis Out BNC. Verify 0 to + 3.5V (nominal) blanking pulse. Verify 0 to - 4.0V (approximately) marker pips if markers are turned on. Signal between marker or retrace pulse should be 0.0 ± 100 mV.

Page 79

				Measurement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
79	Verify FM Input	Main Frequency Tuning: Set to center of frequency band.	Mode: CW	RF Output	None	See Comments		Connect a counter to RF Output. Con- nect + 4.0 Vdc to FM In BNC, frequency change + 5.5 MHz (Minimum). Connect - 4.0 Vdc to FM In BNC, frequency change - 5.5 MHz (Minimum)
80	Verify Frequency Pulling	RF Level: Rotate ccw.						As RF level control is rotated ccw, verify fre- quency does not vary more than 1% of fre- quency setting. Repeat at several other points of fre- quency band.
81	Verify Spurious Signals	RF Level: Full cw.						Connect RF Output to Spectrum Analyzer. Cau- tion: Do not exceed recom- mended input to analyzer. Verify spurious signals at least – 55 dBc.
82	Verify Stability	Main Tuning: Rotate slowly across band.						Verify signal does not break up or show instability
83	Verify Harmonic Signal							Verify har- monic signal is at least: - 12 dBc for Model 962, - 20 dBc for all other models.

Page 80

Table 5-2.	Calibration	Procedure	(Continued)

					Measurement
Step	Step Name	Control Setting	Switch Settings	Test Point	Adjust	Nominal Value	Tolerance	Comments
84	Verify Residual FM	Main Tuning: Rotate slowly across band.	Mode: CW	RF Output	None	See Comments		Verify residual FM is less than: 16 kHz p-p for Model 962. 30 kHz p-p for Model 964. 40 kHz p-p for Model 965. 50 kHz p-p for Model 967.

Page 81

Figure 5-1. Main Board

Page 82

Figure 5-2. Marker Board

5-16

Page 83

Figure 5-4. Digital Control Board

Figure 5-5. Sweep Sawtooth and Blanking Pulse Output

Page 84

Page 85

Figure 5-9. Frequency Measurement

Page 86

Page 87

6.1 FACTORY REPAIR

Wavetek maintains a factory repair department for those customers not possessing the necessary personnel or test equipment to maintain the instrument. If an instrument is returned to the factory for calibration or repair, a detailed description of the specific problem should be attached to the instrument to minimize turnaround time.

6.2 BEFORE YOU START

Since no troubleshooting guide can possibly cover all the potential problems, the aim of this guide is to give a methodology which, if applied consistently, will lead to the problem area. Therefore, it is necessary to familiarize yourself with the instrument by reviewing the general and detailed circuit descriptions (Section 4) in conjunction with the schematics (Section 7). Successful troubleshooting depends upon understanding the circuit operation within each functional block as well as the interrelationship of the blocks.

The intent of this section is to provide the information required to return this instrument to proper operation. Information is divided into two parts. Part one contains the overall instrument troubleshooting block diagram (figure 6-1) and related text, which is useful in isolating major defective blocks within the Micro Sweep. Part two consists of a series of circuit guides (paragraph 6.5) organized by circuit blocks; each guide provides settings and measurements for troubleshooting that block. Also, each circuit guide references related schematics, circuit descriptions, and calibration procedures.

Before removing the Micro Sweep's covers to begin the troubleshooting process, verify the instrument's controls are set correctly. For more information about operating the Micro Sweep, refer to Section 3 of this manual. For example, selecting the CW mode inhibits the sweep function. Furthermore, verify the instruments ac voltage setting is correct for the primary power source; refer to paragraph 2.2.1. Finally, inspect for an incorrect or blown fuse; refer to paragraph 2.2.1.

6.3 ISOLATING A PROBLEM

If the problem still exist after checking the Micro Sweep with the covers on, remove the top cover as follows.

1. Disconnect the Micro Sweep from the power source.
2. To remove the top cover, remove the two screws at the rear of the cover and lift the cover off. It is usually possible to set the top cover with the modular power supply cable still attached to the left of the instrument. If the top cover needs to be disconnected from the Micro Sweep, refer to figure 2-2.
3. When finished checking and repairing the instrument, replace the top cover.

Once the cover is removed, inspect the instrument's components, wiring, and circuit boards for heat damage. Next, rule out calibration as a possible problem. For instance, if the output frequency does not agree with the displayed frequency it is quite possible that resistors R13 or R14 on the Digital Control board need adjustment. Finally, check the power supply (refer to paragraph 6.5.1) and reference (refer to paragraph 6.5.2) voltages.

To successfully troubleshoot this instrument, locate the faulty block, analyze the block, and locate and replace the faulty component.

To locate the faulty block, review figure 6-1 to establish the instrument's signal flow. Next, measure the block's outputs (using the paragraphs referenced on figure 6-1) until the defective block is located. Certain blocks are checked under different several different conditions. Figures 6-2, 6-3, 6-4 shows test points that are useful in isolating blocks.

Once the block is isolated, refer to the appropriate circuit guide; see table 6-2. Set the controls as instructed and take the measurements given to check out the block. All measurements are referenced to ground (TP39). Use the assembly drawing referenced in the circuit guides to locate test points. Paragraph 6.6 gives component troubleshooting information.

6.4 BLOCK ISOLATION

To isolate a problem within the micro sweep, check the test points (see figure 6-1) and refer to the referenced paragraphs.

Page 88

Figure 6-2. Main Board

Page 89

Figure 6-4. Waveform Generator Board

Page 90

6.4.1 Power Supplies

To check out the power supplies, turn on the instrument's power and set it to the CW mode. Refer to paragraph 6.5.1.

6.4.2 References

To check out the references, turn on the instrument's power and set it to the CW mode. Refer to paragraph 6.5.2.

6.4.3 Frequency and Sweep Control Block

Mode: CW

TP12 BUF__TUNE for a 0 (Main Tuning Knob full ccw) to + 10V (Main Tuning full cw).

Probable operation problems: Swp Time set to Ext Tune.

Mode: ∆F or S/S Sweep

TP16SWEEPBUF for a modified ramp (0 to + 10V peak max) variable depending on Start, stop/ΔF and main tuning knob settings.

Probable operation problems: Swp Time set to Ext Tune. Mode set to CW. External Trigger set to on.

6.4.4 Waveform Generator Block

TP10 SWEEPOUT (Waveform Generator Board) 0 to + 10V modified sweep ramp; sweep time varies <20 ms to >20s.

Probable operation problems: Mode set to CW. External Trigger turned on.

TP 11 Z-Axis Output (Waveform Generator Board)<0.5V to > + 2.5V rectangular blanking pulse. Make sure S1-2 and S1-5 are closed.

Hint: check at full band sweep (Mode:S/S Sweep, Start: full ccw, Stop/ΔF: full cw).

Probable operation problems: Mode set to CW. External Trigger turned on. Markers turned off. For markers, sweep width too narrow.

6.4.5 Marker Control Block

TP 22 MARKERS (Marker Board) 1, 2, or 3 rectangular pulses < + 0.5V to >2.5V. Makers must be set and turned on.

Hint: check at full band sweep (Mode:S/S Sweep, Start: full ccw, Stop/ΔF: full cw).

Probable operation problems: Markers turned off. Mode set to CW. Sweep width set too narrow.

6.4.6 YIG Oscillator Control Block

TP 35 T COIL + (Main Board)—see table 6-1. Probable operation problem: Sweep Mode.

TP 33 + BIAS (Main Board) + 13V ± 100mV. Probable operation problems: RF On turned off.

Oscillator Temperature Probe input: J10-1 (Main Board) + 5.05 ± 0.25V; J10-2 + 0.3 ± 0.050V.

Table 6-1. YIG Control

Test Pont	Model
	962	964	965	967
TP 35 (Main Tuning full cw)	- 3.7 to - 4.8V	– 3.8 to – 4.5V	- 3.4 to - 3.9V	– 5.1 to – 5.6V
TP 35 (Main Tuning full ccw)	- 0.8 to - 1.2V	— 1.5 to — 1.9V	– 1.9 to – 2.2V	3.6 to 4.7V

6.4.7 Modulation and Leveling

TP26 FMCOIL - (Main Board) ±2.5V triangle TP27 FM COIL + (Main Board) ±2.5V triangle Connect FM In to ±2.5V triangle source. Probable operation problems: No input FM signal.

TP25 PINDIODE (Main Board) 0.0 ± 0.2V (RF Level: full cw); -0.75 ± 0.1V (RF Level: full ccw) Mode: CW and No external leveling (+0.75V for Model 962 only). Probable operation problems: Input to AM In connector, automatic leveling on.

Table 6-2. Circuit Guides

Circuit Guide	Paragraph
Power Supplies	6.5.1
Modular Power Supply	6.5.1.1
± 13V Regulators	6.5.1.2
± 6.2V Regulators	6.5.1.3
Reference Block	6.5.2
10V Reference	6.5.2.1
+ 10V Buffered Reference	6.5.2.2
- 10V Reference	6.5.2.3
Digital Control Block	6.5.3
Digital Control	6.5.3.1
Blink Timer	6.5.3.2
Waveform Generator Block	6.5.4
Constant Current Source	6.5.4.1
Comparator	6.5.4.2

Page 91

Table 6-2. Circuit Guides (Cont)

Circuit Guide	Paragraph
Waveform Generator Block (Cont) Sweep Shaper Top Flat Comparator Bottom Flat Comparator Monostable Retrace Comparator Summing Comparator Z-Axis Switching and Buffer	6.5.4.3 6.5.4.4 6.5.4.5 6.5.4.6 6.5.4.7 6.5.4.8
Frequency and Sweep Control Block	6.5.5
Frequency Control and Buffer	6.5.5.1
Sweep Stop/ΔF	6.5.5.2
Start	6.5.5.3
CF Buffer	6.5.5.4
ΔF Clipper	6.5.5.5
Start/Stop Sweep Buffer	6.5.5.6
Display Start/Stop Controls	6.5.5.7
External Tune Switching	6.5.5.8
YIG Oscillator Control Block	6.5.6
Temperature Compensation	6.5.6.1
YIG Main Tuning Coil Driver	6.5.6.2
Oscillator Bias Supply	6.5.6.3
YIG Oscillator	6.5.7
Modulation and Leveling Block	6.5.8
RF and AM Input Summing Amplifier	6.5.8.1
PIN Diode Attenuator Driver	6.5.8.2
Automatic Level Control	6.5.8.3
FM Coil Drive	6.5.8.4
Marker Control Block	6.5.9
Marker A to D and D to A Conversion	6.5.9.1
Marker Enable Decoder	6.5.9.2
Marker Sweep Comparator	6.5.9.3
Transition Detector	6.5.9.4
Display Block	6.5.10
Voltmeter and Display	6.5.10.1
Offset and Scaling Network	6.5.10.2
Display Multiplexer	6.5.10.3

6.5 TROUBLESHOOING GUIDES

6.5.1 Power Supplies

6.5.1.1 Modular Power Supply

Related information in this manual. Schematic: None. Circuit Description: Paragraph 4.2.1.1. Calibration Procedure: None.

Set the Micro Sweep's front panel controls and pushbuttons as shown and perform the checks in table 6-3.

Control/Pushbutton	Setting
Main Tuning knob	Full cw
Power	On
RF Level	Full cw
Start	Full ccw
Stop/∆F	Full cw
Swp Time	Full cw
Markers	All Off
Mode	CW
Ext Trig	Off
Ext Level	Off
RF On	On

Table 6-3. Modular Power Supply

Test Point	Voltage	Tolerance	Line Noise
TP 6	+ 16.2V	± 0.5V	<100 mVp-p
TP 3	- 16.2V	± 0.5V	<100 mVp-p

6.5.1.2 ±13V Regulators

Related information in this manual.
Schematic: 0103-00-1848 Sheet 2.
Circuit Description: Paragraph 4.2.1.2
Calibration Procedure: Table 5-2, steps 3 and 4.

Set the controls as shown in paragraph 6.5.1.1 below and make the checks in table 6-4.

NOTE

The 3-terminal regulator ICs are found on the rear panel. The input and output connections, to filter capacitors and output level setting voltage dividers on the main circuit board, are made through connector J12.

Table 6-4. ±13V Regulator

Test Point	Voltage	Tolerance	Line Noise
J12-8/TP6	+ 16.2V	± 0.5V	<100 mVp-p
TP 7	+ 13.0V	± 0.5V	<100 mVp-p
J12-6	1.25V (±50mV) less positive than J12-7
J12-2/TP3	16.2V	± 0.5V	<100 mVp-p
TP 4	— 13.0V	± 0.5V	<100 mVp-p
J12-4	1.25V (±50mV) less negative than J12-5

Page 92

6.5.1.3 ± 6.3V Regulators

Related information in this manual. Schematic: 0103-00-1848 Sheet 2. Circuit Description: Paragraph 4.2.1.3. Calibration Procedure: Table 5-2, steps 5 and 6.

Set the controls and pushbuttons as shown, and make the checks in table 6-5.

Control/Pushbutton	Setting
Main Tuning knob	Full cw
Power	On
RF Level	Full cw
Start	Full ccw
Stop/∆F	Full cw
Swp Time	Full cw
Markers	All Off
Mode	CW
Ext Trig	Off
Ext Level	Off
RF On	On

Table 6-5. ± 6.3V Regulator

Test Point	Voltage	Tolerance
VR1-3	+ 13.0V	± 0.5V
TP 8	+ 6.3V	± 100 mV
VR1-1	1.25 (±50 mV) less than VR1-2
VR2-2	- 13.0V ± 0.5V
TP 5	— 6.3V	± 100 mV
VR2-1	1.25V (±50 mV) less than VR5-3

NOTE

U19 and U21 are the most likely places to look for excessive current drain on these regulators.

6.5.2 References

6.5.2.1 +10V Reference

Related information in this manual. Schematic: 0130-00-1848 Sheet 1. Circuit Description: Paragraph 4.2.2.1. Calibration Procedure: Table 5-2, step 7.

Set the controls and pushbuttons as shown below, and make the measurements as shown in table 6-6.

Control/Pushbutton	Setting
Main Tuning knob	Full cw
Power	On
RF Level	Full cw
Start	Full ccw
Stop/∆F	Full cw
Swp Time	Full cw
Markers	All Off
Mode	CW
Ext Trig	Off
Ext Level	Off
RF On	On

Table 6-6. + 10V Reference Supply

Test Point	Voltage	Tolerance
U1-6	+ 10.6V	± 0.2V
U1-3	+ 6.9V	± 0.35V
U1-2	± 10 mV of U1-3 value
TP 1	+ 10.00V	± 1mV (Ref: Table 5-2 step 7)

6.5.2.2 + 10V Buffered Reference

Related information in this manual. Schematic: 0103-00-1848 Sheet 1. Circuit Descritpion: Paragraph 4.2.2.2. Calibration Procedure: Table 5-2, step 8.

Set the pushbuttons and controls as shown, and make the checks in table 6-7.

Control/Pushbutton	Setting
Main Tuning knob	Full cw
Power	On
RF Level	Full cw
Start	Full ccw
Stop/∆F	Full cw
Swp Time	Full cw
Markers	All Off
Mode	CW
Ext Trig	Off
Ext Level	Off
RF On	On

Page 93

Table 6-7. + 10V Buffered Supply

Test Point	Voltage	Tolerance
TP 1	+ 10V	± 1mV
TP 2	+ 10V	± 10 mV
U2C-8	+ 10.7V	± 100 mV
Q11 Collector	+ 13V	± 0.5V

6.5.2.3 - 10V Reference

Related information in this manual. Schematic: 0103-00-1854. Circuit Description: Paragraph 4.2.2.3. Calibration Procedure: None.

Set the controls and pushbuttons as shown, and make the checks in table 6-8.

Setting
Full cw
On
Full cw
Full ccw
Full cw
Full cw
All Off
CW

Control/Pushbutton	Setting
Ext Trig	Off
Ext Level	Off
RF On	On

Table 6-8	10	/ Reference	Supply
10010-0-0		a menerence	ouppiy

Test Point	Voltage	Tolerance
U30B-6	OV	± 25 mV
TP 18	— 10V	± 200 mV
U30B-5	0.0V (ground)	± 25 mV

6.5.3. Digital Control Block

6.5.3.1 Digital Control

Related information in this manual. Schematic: 0103-00-1857 Sheet 1. Circuit Description: Paragraph 4.2.3. Calibration Procedure: None.

Tables 6-9, 6-10, 6-11 show the logic states for the control lines within the Micro Sweep. When a front panel pushbutton is pressed, the appropriate input to the programmable array logic ICs goes high causing the appropriate control lines to change. Figure 6-5 shows the timing relationship of the Digital Control Clock.

Figure 6-5. Digital Clock Timing

Page 94

Table 6-9. Control Lines

Control Line	Description	Destination
UPDATE, MKRSET, J4-4	Goes low when Update pushbutton pressed.
LEV, J4-6	Goes low when Ext Level pushbutton pressed.	Automatic Level Control
RFLITE, J4-5	Goes low when RF On pushbutton pressed.	RF On Control
EXTTO, U1-15	Toggles high when Ext Trig pushbutton pressed.	U3
MODE 1, J4-2 (S/S LITE)	Low order bit for mode control; see table 6-10.	PAL U3 Sweep Stop/∆F, Sweep Selector
MODE 2, J4-10 (DF LITE)	High order bit for mode control.	Sweep Stop/∆F, Sweep Selector
ANYMODE, U1-19	Pulses high when any pushbutton to PAL U1 pressed.	U2
ANYIN, U1-12	Goes low when any pushbutton on front panel is pressed.	U4-15
DM3, J4-11 DM2, J4-12 DM1, J4-13	Display mode control bits; see table 6-11.	U3 Marker DAC Display Multiplexer
M3, J4-14 M2, J4-15 M1, J4-16	Goes low when M3 (Marker) turned on. Goes low when M2 (Marker) turned on. Goes low when M1 (Marker) turned on.	U3 Comparator Marker Output
CW LITE	Goes low when CW Mode selected.	Voltmeter/Display Comparator Positive Peak Comp. CW/SWEEP Selector
SWEEP, J20B-7	Goes high when any of the sweep modes are selected.	Voltmeter/Display
EXTT, J4-20	Goes low when External Trigger selected. Only active in sweep modes.	Trigger Control
M3D, U3-14 M2D, U3-13 M1D, U3-12	Controls marker LEDs; see figure 6-6.	Marker LEDs

Page 95

Table 6-10. Mode Logic

State	Mode 1	Mode 2
Display Test Start/Stop	0	0 0
ΔF	0	1
CW	1	1

Table 6-11. Display Frequency Logic

Displayed Frequency	DM1	DM2	DM3
ΔF	0	0	0
M1	1	0	0
M2	0	1	0
M3	1	1	0
STOP	0	0	1
Start	1	0	1
CF	0	1	1
CW	1	\| 1	1

LED OFF (MARKER OFF AND

MARKER FREQUENCY NOT BEING DISPLAYED)

6.5.3.2 Blink Timer

Related information in this manual. Schematic: 0103-00-1857 Sheet 2. Circuit Description: Paragraph 4.2.3.5. Calibration Procedure: None.

Refer to paragraph 4.2.3.5 of the circuit description for details on the blink timer.

6.5.4 Waveform Generator

6.5.4.1 Constant Current Source

Related information in this manual. Schematic: 0103-00-1875. Circuit Description: Paragraph 4.2.4.1. Calibration Procedure: Table 5-2, step 19.

Set the controls as shown, and take the measurements listed in table 6-12.

>+ 2.4V

Control/Pushbutton	Setting
Main Tuning knob	Full cw
Power	On
RF Level	Full cw
Start	Full ccw
Stop/∆F	Full cw

Figure 6-6. Marker LED Timing*

*Measured at the cathodes of CR16, CR17, and CR18, conditions apply to all three LEDS.

Page 96

Control/Pushbutton	Setting
Swp Time	As directed in
	table 6-12
Markers	All Off
Mode	S/S Sweep
Ext Trig	Off (Autotrigger)
Ext Level	Off
RF On	Off

Table 6-12. Constant Current Source

	Sweep Time
Test Point	Full cw	Full ccw (But not in the Ext Tune position)
U33C-11, U33D-14	+ 10 ± 0.01V	+ 10 ± 0.01V
U32C-10 U32C-9	+ 0.1V + .1V, 08V	+0.1V, +.1V,08V
U32C-8	- 10.2 to - 10.8V	+ 13 ± 0.5V (~3mV < + 13V supply)

6.5.4.2 Comparator

Related information in this manual. Schematic: 0103-00-1875. Circuit Description: Paragraph 4.2.4.1. Calibration Procedure: Table 5-2, step 17.

Set the controls as shown, and take the measurements as listed in table 6-13 and figure 6-7.

Setting
Full cw
On
Full cw
Full ccw
Full cw
Full cw
All Off
S/S Sweep
Off (Autotrigger)
Off
Off

Table 6-13. Comparator

Test Point	Voltage	Tolerance
U26-5	+ 10.0V	± 0.2V
U26-4	+ 3.5V	± 1V
U26-8	>11.0V

Figure 6-7. Comparator Waveforms

6.5.4.3 Sweep Shaper

Related information in this manual. Schematic: 0103-00-1875. Circuit Description: Paragraph 4.2.4.1. Calibration Procedure: Table 5-2, step 18.

Set the controls as shown, and measure the waveforms as shown in figure 6-8.

Control/Pushbutton	Setting
Main Tuning knob	Full cw
Power	On
RF Level	Full cw
Start	Full ccw
Stop/∆F	Full cw
Swp Time	Full cw
Markers	All Off
Mode	S/S Sweep
Ext Trig	Off (Autotrigger
Ext Level	Off
RF On	Off

Page 97

Figure 6-8. Shaper Waveforms

Page 98

6.5.4.4 Top Flat Comparator

Related information in this manual. Schematic: 0103-00-1875. Circuit Description: Paragraph 4.2.4.2. Calibration Procedure: None.

Set the controls as shown, and take the measurements as shown in figure 6-9.

Control/Pushbutton	Setting
Main Tuning knob	Full cw
Power	On
RF Level	Full cw
Start	Full ccw
Stop/∆F	Full cw
Swp Time	Full cw
Markers	All Off
Mode	S/S Sweep
Ext Trig	Off (Autotrigger)
Ext Level	Off
RF On	Off

6.5.4.5 Bottom Flat Comparator

Related information in this manual. Schematic: 0103-00-1875. Circuit Description: Paragraph 4.2.4.2. Calibration Procedure: None.

Set the controls as shown, and take the measurements as shown in figure 6-10.

Control/Pushbutton	Setting
Main Tuning knob	Full cw
Power	On
RF Level	Full cw
Start	Full ccw
Stop/∆F	Full cw
Swp Time	Full cw
Markers	All Off
Mode	S/S Sweep
Ext Trig	Off (Autotrigge
Ext Level	Off
RF On	Off

Page 99

6.5.4.6 Monostable Retrace Comparator

Related information in this manual. Schematic: 0103-00-1875. Circuit Description: Paragraph 4.2.4.2. Calibration Procedure: None.

Set the controls as shown, and make the measurements as shown in figure 6-11.

Control/Pushbutton	Setting
Main Tuning knob	Full cw
Power	On
RF Level	Full cw
Start	Full ccw
Stop/∆F	Full cw
Swp Time	Full cw
Markers	All Off
Mode	S/S Sweep
Ext Trig	Off (Autotrigger)
Ext Level	Off
RF On	Off

U34C-13 U34C-13 U34B-4 U34B-4 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

6.5.4.7 Summing Comparator

Related information in this manual. Schematic: 0103-00-1875. Circuit Description: Paragraph 4.2.4.2. Calibration Procedure: None.

Set the controls as shown, and make the measurements as shown in figure 6-12.

Control/Pushbutton	Setting
Main Tuning knob	Full cw
Power	On
RF Level	Full cw
Start	Full ccw
Stop/ΔF	Full cw
Swp Time	Full cw
Markers	All Off
Mode	CW
Ext Trig	Off (Autotrigger
Ext Level	Off
RF On	Off

Page 100

6.5.4.8 Z-Axis Switching and Buffer

Related information in this manual. Schematic: 0103-00-1875. Circuit Description: Paragraph 4.2.4.2. Calibration Procedure: Table 5-2, step 22.

Set the controls as shown, and take the measurements as shown in figure 6-13. See table 6-14 for switch S1 settings.

Setting
Full cw
On
Full cw
Full ccw
Full cw
Full cw
All On, set markers at
1/3, 1/2, 2/3 band points
S/S Sweep

Control/Pushbutton Setting

Ext Trig	Off (Autotrigger)
Ext Level	Off
RF On	Off

Table 6-14. Switch S1 Settings

Switch	Function
S1-2*	Closed selects negative going marker pulses.
S1-3	Closed selects positive going marker pulses.
S1-4	Closed selects negative going blanking pulses.
S1-5*	Closed selects positive going blanking pulses.

*Factory selected Z-Axis output.

Figure 6-13. Z-Axis Waveforms

Note: Switch S1 set as follows: S1-5 and S1-2 Closed, S1-4 and S1-3 Opened; Markers are turned on.