This section is written as a general guide for those having previous knowledge and
experience with these kinds of equipment. It is not intended to contain a complete
statement of all safety precautions, which should be observed by personnel using this or
other electronic equipment.
To reduce the risk of fire or electric shock, do not expose this equipment to rain or
moisture. Do not open the cabinet. Refer servicing to qualified personnel.
1. READ INSTRUCTIONS - All safety, installation, and operating instructions should be
read before the equipment is operated.
2. RETAIN INSTRUCTIONS - The safety and operating instructions should be retained
for future reference.
3. FOLLOW INSTRUCTIONS - All safety, installation, and operating instructions should
be followed.
4. GROUNDING AND POLARIZATION - The TM-200 Modulator is equipped with a
three prong grounded power plug. Do not remove the ground prong from the plug.
Do not use an AC receptacle where the plug blades cannot be fully inserted.
5. SERVICING - Do not attempt to service this equipment yourself as opening or
removing covers may expose you to dangerous voltage or other hazards and will
void the warranty. Refer all servicing to qualified service personnel.
6. DAMAGE REQUIRING SERVICE - Unplug this equipment and refer servicing to
qualified service personnel under the following conditions:
• if the power cord or plug is damaged.
• if liquid has been spilled or objects have fallen into the equipment.
• if the equipment has been exposed to rain or water.
• if the equipment does not operate normally by following the operating
instructions. Adjust only those controls covered by the operating instructions. An
improper adjustment may result in damage and will often require extensive work
by a qualified technician to restore the equipment to its normal operation.
• if the equipment has been dropped or the cabinet has been damaged.
• if the equipment exhibits a distinct change in performance.
TM-200 Issue 1.02 November 2005 Page 2 of 64
Safety and First Aid
Personnel engaged in the installation, operation, maintenance, or servicing of electronic
equipment are exposed to the hazard of high voltage. It is imperative that all safety
regulations and precautions are consistently observed. Knowledge of first aid
procedures is recommended. The following information is presented as a reference
only.
• At all times, avoid placing any part of the body in series between ground and circuit
points, whether power is on or off.
• Dangerous voltage may be present in equipment even though power is off. Do not
open the cabinet. Refer servicing to qualified service personnel.
• It is the duty of all personnel to be prepared to give adequate emergency first aid
treatment and thereby prevent avoidable loss of life.
• There are three principle degrees of burns, recognizable as follows:
• a first-degree burn reddens the skin.
• a second-degree burn blisters the skin.
• a third degree burn chars the flesh and frequently places the victim in a state of
shock accompanied by respiratory paralysis.
• Respiratory paralysis can cause death by suffocation within seconds. It is imperative
that the approved methods of artificial respiration are initiated immediately and
continue until the victim’s breathing is normal.
• A muscular spasm of unconsciousness may render the victim unable to break free of
the electric power. If this is the case, turn the power off immediately.
DO NOT TOUCH THE VICTIM OR YOU MAY SHARE THE SAME
PREDICAMENT.
• If the power cannot be turned off immediately, very carefully loop a dry rope, article
of clothing, length of strong cloth or a rolled-up newspaper around the victim and pull
the victim free of the power source. Carefully avoid touching the victim or clothing.
• Once free of the power source, the victim must be placed in a reclining position and
covered with a blanket or newspapers to keep warm. At the first opportunity, enlist
help in summoning a doctor. If a doctor cannot be summoned, transport the victim to
the doctor or a hospital. Be sure the victim is kept well covered and warm while
awaiting professional treatment.
TM-200 Issue 1.02 November 2005 Page 3 of 64
2.0 W
ARRANTY
Technalogix Ltd. products have been completely tested and found to meet specifications
and be in proper operating condition. They are warranted to be free from defects in
materials and workmanship for a period of one year from the date of shipment.
Technalogix Ltd. will not be liable for damages of whatever nature arising out of or in
connection with the equipment or its use thereof. Technalogix does not assume
responsibility for injury or damage resulting from the practices of untrained or unqualified
personnel in the handling of this equipment.
Technalogix Ltd. warranty does not include:
• misuse, neglect or accident.
• incorrect wiring and /or improper installation.
• unauthorized repairs, modifications or use in violation of instructions issued by
Technalogix.
• incidental or consequential damages as a result of any defect.
• reshipment cost or insurance of the unit or replacement units or parts.
• acts of God.
Technalogix agrees, at our option, to remedy warranted defects or furnish a new part in
exchange for any part of a unit which, under normal installation, use and service,
becomes defective. The user will pay for transportation costs to and from the repair
center.
To claim your rights under this warranty:
• Contact Technalogix and describe the problem in as much detail as possible. See
troubleshooting section in this manual. If a solution cannot be found at this time, it
may be determined that the unit will have to be returned to Technalogix for repair.
• Package equipment carefully for prepaid shipment to Technalogix. Include a written
description of the problem experienced and a copy of the original invoice establishing
warranty status.
Technalogix reserves the right to make revisions in current production of the equipment
and assumes no obligation to incorporate these changes in earlier models.
TM-200 Issue 1.02 November 2005 Page 4 of 64
3.0 D
ESCRIPTION AND SPECIFICATIONS
General Description
The TM-200 is a high output modulator that eliminates the need for preamplifiers prior to
the power amplifier system. The modulator first processes baseband audio and video
information to provide an IF output consisting of a visual IF carrier at 45.75 MHz, using
amplitude modulation, and an aural IF carrier at 41.25 MHz, using frequency modulation.
Pre-correction is implemented at IF frequencies with a Signal Conditioning Board.
Frequency conversion circuitry then translates the modulator’s IF carriers to VHF and
UHF television frequencies. All operating controls are located on the front panel, and
will be discussed in later section, while input and output interfaces are on the back plate.
An aural loop through is provided to properly set transmitter power.
Standard Features
• Totally microprocessor controlled with self-diagnostic monitoring.
• Optional aural sub-carrier and baseband audio input
• Phase lock loop FM audio.
• BTSC stereo compatible.
• External separate audio/video and composite IF loop-through.
• RS-232 control option
• Sound carrier level adjustable –10 dB to –15 dB.
• Video delay pre-distortion network meets FCC 73.687.
• High stability TCXO, ± 250 Hz
• Non-volatile memory retains channel selection after power loss.
• Video Detection turns off carrier in event of loss of video.
• IF pre-correction allow slope/knee linearization of signal.
• Sync level adjustment to ensure sync tip at proper levels.
• White clip and DC restoration of baseband video signal.
• 50-ohm RF Output and tap-off
TM-200 Issue 1.02 November 2005 Page 5 of 64
Available Options
• 4.5 MHz sub carrier and baseband audio inputs.
• Dual RS-232 control with daisy chain capabilities that allow for remote control by
PC workstation.
• HRC Output Frequency Set - This feature is controlled by an internal dip switch
assembly, DS-1. The switch is located near the right front corner (with the panel
facing you) between the test point and the output converter module. DS-1 is
clearly marked on the PCB. Switch #3 placed in the OFF position switches the
output frequency to HRC on all channels. The switch is normally set to ON at the
factory.
TM-200 Issue 1.02 November 2005 Page 6 of 64
Block Diagram
The baseband input source enters through a Video In connector, and Baseband Audio In
or 4.5 Audio In connector on the back of the modulator. The connectors are mounted
directly on the A/V Modulation PCB where the IF output is generated. The baseband
video signal passes into the modulator, through a group delay filter, and onto the Signal
Conditioning PCB to the video detect/sync level adjust section. The IF signal from the IF
loop on the modulator is connected through the IF pre-correction portion of the same
Signal Conditioning PCB. The visual IF carrier and the aural IF carrier are then
combined before entering the Upconverter PCB. The outputs are at RF frequencies of
945.75 MHz for the visual carrier and 941.25 MHz for the aural carrier. Then, the signal
passes through a Downconverter section allowing a user selectable VHF or UHF
broadcast television channel. Finally, the signal passes through an output amplifier
which increases the RF signal level typically to 15 dBm.
TM-200 Issue 1.02 November 2005 Page 7 of 64
VIDEO IN AUDIO IN
Baseband Audio 4.5 MHz Audio
Aural IF Carrier
Visual IF Carrier
A/V Modulation PCB
Combiner
Upconverter
Video Detect
Downconverter
In Out
Signal Conditioning Board Display and Control Board
Output
IF Pre-correction
Out In
RF Output
Amplifier
TM-200 Issue 1.02 November 2005 Page 8 of 64
Specifications
RF Characteristics
Frequency range 7 to 750 MHz
Frequency Response (one channel) ±0.5 dB
Frequency Stability ±250 Hz
RF Output Level +60 dBmV max
Output Impedance 50 Ohms
Harmonics > 60 dB below rated power
Predominant Intermodulation Distortion dBc = decibels below visual carrier
Input Level to modulator (for 87.5% modulation) 1.0 V
Differential Phase (at 87.5% modulation) ±2 Degrees
Differential Gain (at 87.5% modulation) 2%
Group Delay < ±40 nS
Video Group Delay Pre-emphasis Conforms to IC/FCC specifications
K-Factor 1.9% for 2T Pulse
Hum and Noise > 60 dB below rated power
Aural Characteristics
Input: 50 Hz – 15 KHz 0 dBm (0.8V)
Impedance 600 ohms, balanced
Frequency Response +/- 1.0 dB
Frequency Tolerance, +/- 500 Hz 4.5 MHz
Frequency Deviation +/- 25 KHz
Harmonic Distortion 1% max
Preemphasis (mono)
Internally Defeatable
PP
75 µs
TM-200 Issue 1.02 November 2005 Page 9 of 64
IF Section
Output Impedance 75 ohms, unbalanced
Video IF level
+ 37 dBmV, +97 dBµV
Audio IF Level +22 dBmV
Adjustable
+82 dBµV
Return Loss > 14 dB
IF Frequency, Video Carrier 45.75 MHz
IF Frequency, Audio Carrier 41.25 MHz
Video Sound Spacing + 4.5 MHz
Vestigial side-band width 0.05 MHz
Second IF Frequency 945.75 MHz
Physical Characteristics
Power Requirements 100-130 Vac, 210-230 Vac, 50/60 Hz,
1 Aac at 110 Vac
Operating Temperature 0 - 50°C
Weight 12 lbs
Dimensions (modulator only) W-19", D-16" with connectors, H- 2U-
high
TM-200 Issue 1.02 November 2005 Page 10 of 64
Signal Conditioning Module
The TM-200 modulator includes a separate circuit board called the Signal Conditioning
Module. The Signal Conditioning PCB contains the video detect/sync level adjust
section in addition to the IF pre-correction section. The baseband video signal passes
into the modulator, through a group delay filter, and onto the Signal Conditioning PCB to
the video detect/sync level adjust section. The IF signal from the IF loop on the
modulator are connected through the IF pre-correction portion of the same PCB. The
Signal Conditioning features are as follows:
1. Sync Level Adjust - Allows the user to adjust the sync level to maintain the
proper level. Adjustment is made via front panel.
2. Video Detect - Turns off the 24Vdc supply to the final amplifier stage in the TM200 in the event of missing video input. The power supply for the final amplifier
(+24Vdc) is routed through a relay on the Signal Conditioning PCB. In the event
of a missing video signal, the relay contact is opened and the +24Vdc is
disconnected from the final amplifier stage.
3. IF Pre-Correction – Allows the user to optimize the linearity of their power
amplifier using slope-knee adjustments available from front panel. Adjustment
will alter several RF performance parameters including in-band intermodulation
products, differential phase and gain, and others.
The input and output impedance of the Signal Conditioning PCB is 75-ohms. Baseband
video connections are made via RCA connectors for the sync level adjust and video
detect sections and the IF connections are made via F connectors. The Signal
Conditioning PCB can be bypassed, if necessary.
TM-200 Issue 1.02 November 2005 Page 11 of 64
4.0 I
NSTALLATION
This section contains installation recommendations, unpacking, inspection, and
installation instructions for the Technalogix TM-200 Modulator. Carefully read all material
in this section prior to installation. Also read and review operating procedures later in this
section.
Building Recommendations
The quality of the building is of great importance if you are to expect long life and
continued performance from the modulator. The building must be clean, dry,
temperature controlled and secure. The modulator takes up a single 1-U high space on a
19” rack. Don’t forget to allow space in the building for any additional racks to house test
equipment, a workbench area, line regulating transformers, ladders, equipment and
parts storage, first aid kit, emergency generator if used, as well as heating and cooling
devices that may be unique to your installation. A sloping roof will tend to develop leaks
less rapidly. The building should be well roofed with good material. The cooling load will
be lowered with reflective or light colored roofing material.
Heating and Cooling Requirements
The environment’s temperature will contribute greatly to the length of the modulator’s
life. Technalogix recommends that the building’s filtered air intake must have capacity for
all air-flow in the building plus an additional 20%. Keep the intake below the roofline to
avoid intake of solar heated air. Please ensure that the intake and exhaust areas are on
the same side of the building to avoid pressure differentials during windy conditions.
Also, do not position intake near exhaust’s preheated air. If air conditioning is required to
cool the shelter, discuss the situation with a qualified HVAC technician. Under average
conditions, 12,000 BTUs will cool approximately 500 square feet to a comfortable level.
TM-200 Issue 1.02 November 2005 Page 12 of 64
Electrical Service Recommendations
Technalogix recommends that a qualified, licensed local electrician be consulted for the
required electrical service. We suggest local electricians because:
• The personnel knows the local codes
• The personnel can be on site readily
• You are apt to get better overall support if you give what business you can to local
suppliers
Technalogix recommends that proper AC line conditioning and surge suppression be
provided on the primary AC input to the power amplifier. All electrical service should be
installed with your national electrical code in your area, any applicable provincial or state
codes, and good engineering practice. Special consideration should be given to lightning
protection of all systems in view of the vulnerability of most transmitter sites to lightning.
Lightning arrestors are recommended in the service entrance. Straight and short
grounds are recommended. The electrical serviced must be well grounded. Do not
connect the unit to an open delta primary power supply, as voltage fluctuations could
harm the unit. Branch your circuits. Do not allow your lights, your workbench plugs, and
your transmitting or translating equipment off of one circuit breaker. Each transmitter
should have its own circuit breaker, so a failure in one does not shut off the whole
installation.
TM-200 Issue 1.02 November 2005 Page 13 of 64
Antenna and Tower Recommendations
Your preliminary engineering workgroup should establish your antenna and tower
requirements, both for receiving and transmitting antennas. Construction of sturdy, high
quality antenna/tower systems will pay off in terms of coverage of your service area, the
overall quality and saleability of your radiated signal, and reduced maintenance
expenses. Technalogix provides complete turnkey antenna systems if needed.
Transmitting antennas can enhance or seriously impair the transmitter output. It is
assumed that one has been selected prior to system installation, but the best-designed
antenna system will function poorly if shortcuts and compromises are used during
installation. Follow the manufacturer’s instructions exactly, along with any engineering
data prepared for the site.
The selection, routing, and length of coaxial cable is extremely important in the
installation. If there is a 3 dB line loss in the cable between your unit’s output and the
transmitting antenna, a 500 watt unit will only deliver 250 watts to the antenna. Buy the
best cable you can obtain, route it via the shortest way to the antenna, and keep it
straight. Do not form it into sharp bends on its way. Do not use any more cable fittings
for the installation than absolutely necessary. All cautions here apply equally to all
coaxial cables in the system - input and output. The better known tower manufacturers
offer complete technical and safety documentation with their towers. Be sure that you
have this information as it regards wind loading, guying, etc. Be absolutely safe and
certain about this aspect as human lives may be at stake.
TM-200 Issue 1.02 November 2005 Page 14 of 64
Shelter Security
The FCC requires that the transmitter be secure from entry or control by unauthorized
persons, and that any hazardous voltages or other dangers (including most tower bases)
be protected by locks or fences as necessary to protect personnel and prevent
unauthorized tampering or operation. Security of the building further implies that it be
secure from wildlife. Use sturdy construction materials, including sheet metal if
necessary. Holes around conduit, cable, and other similar entry points should be stuffed
with steel wool and caulked to prevent entry of wildlife. Other features of security for your
shelter may include its location with respect to the prevailing wind conditions. A location
leeward of some natural topographical feature will prevent wind damage and snowdrifts.
Check the soil runoff conditions that may slow or hasten wind or water erosion and other
concerns that may be unique to your location.
TM-200 Issue 1.02 November 2005 Page 15 of 64
Unpacking and Inspection
Check the outside of the container. Carefully open the container and remove the
modulator. Retain all packing material that can be reassembled in the event that the
equipment must be returned to the factory.
Exercise care in handling equipment during inspection to prevent
damage due to rough or careless handling.
Visually inspect the enclosure of the modulator for damage that may have occurred
during shipment. Check for evidence of water damage, bent or warped chassis, loose
screws or nuts, or extraneous packing material in connectors. Inspect all connectors for
bent connector pins. If the equipment is damaged, a claim should be filed with the carrier
once the extent of the damage is assessed. Technalogix cannot stress too strongly the
importance of immediate careful inspection of the equipment and subsequent immediate
filing of the necessary claims against the carrier if necessary. If possible, inspect the
equipment in the presence of the delivery person. If the equipment is damaged, the
carrier is your first area of recourse. If the equipment is damaged and must be returned
to the factory, phone for a return authorization. Claims for loss or damage may not be
withheld from any payment to Technalogix, nor may any payment due be withheld
pending the outcome thereof. Technalogix cannot guarantee the carrier’s performance.
TM-200 Issue 1.02 November 2005 Page 16 of 64
Location and Function of Controls and Connectors
The following illustrations depict the location of the installation connectors when
installing the power amplifier with a modulator or processor.
FRONT
BACK
Audio Deviation – Allows user to control extent of audio deviation. Original factory
setting at 25 KHz deviation using standard pre-emphasis curve.
Audio/Video Display Select - Provides a graphical representation of audio deviation and
visual modulation levels on an LED bar graph. The switch selects between audio
deviation or visual modulation.
Video Modulation -- Allows user to control extent of video modulation. Original factory
setting at 87.5% video modulation with 1.0 Volt peak to peak baseband input video
signal.
Frequency Offset Select – Toggles between +10 KHz, 0KHz, and –10 KHz frequency
offset.
TM-200 Issue 1.02 November 2005 Page 17 of 64
Aural Carrier Level - Allows user to set aural carrier level relative to visual carrier level.
Modulator is factory tested at –10 dBc (decibels below visual carrier).
Output Select – Selects the desired channel of operation. If you require a lower channel
than the one currently displayed, push the toggle switch down. The channels will
change one at a time as many times as you press the switch. Holding the select switch
in the up or down position will “scan” to the desired channel. It is normal for the
frequency lock LED to turn off during and for a few seconds after, changing channels.
The switch must be held up or down initially for three seconds. This helps to ensure that
no accidental channel changes will occur.
Output Level – Sets visual carrier output level.
RF Out Test Point – Provides a sample of the RF output level which is 20 dB below the
actual value. RF test point is only a relative indicator of the actual RF output level and
may vary. All RF operating measurements should be made at the RF output of the unit.
RF Output - Modulated Audio/ Video output capable of +60 dBmV levels using built in
low distortion hybrid amplifiers.
RS-232 Ports – Set up for optional RS-232 control option.
Combined IF Input/ Output – 45.75 MHz visual carrier and 41.25 MHz audio carrier
intermediate frequency signal loop.
Audio Input/ Ouput Loop – Available for baseband audio processing.
Video Input/ Output Loop - Available for baseband video processing.
IF Pre-Correction Loop – Allows pre-correction adjustment to improve linearity,
intermodulation performance, and other RF parameters. Internally connected to Signal
Conditioning PCB.
Video In – Connection for 1.0 Volt peak to peak video source.
Balanced Baseband Audio In – Used to connect a 1 Volt peak to peak baseband audio
signal. For balanced input connection, connect 1 audio input lead to the left terminal on
the connector and the other audio input lead to the right terminal. For an unbalanced
input connection, connect one audio input lead to the left terminal on the connector and
the other audio input lead to the centre terminal. The center terminal is chassis ground.
TM-200 Issue 1.02 November 2005 Page 18 of 64
5.0 O
PERATING PROCEDURE
Preliminary Hook-up
1. Terminate modulator into a 50 ohm load before applying power.
2. Connect the power cord of the Technalogix TM-200 agile modulator to a proper
electrical source as indicated on the back of the unit.
3. Observe the front panel. If power is applied and present, the red power LED will
illuminate. Also, all the elements of the displays behind the display readout
window will illuminate momentarily as a display test.
4. Observe the numbers displayed behind the display readout window after the test.
They will indicate:
• Microprocessor software version;
• Internal option dipswitch settings;
• RS-232 unit ID (if so equipped); and
• Last tuned channel.
5. After a moment, the Lock Detect LED will illuminate.
TM-200 Issue 1.02 November 2005 Page 19 of 64
Setup of Output Level and Channel Selection
1. Connect a spectrum analyzer, or a field strength meter tuned to the frequency of
the video RF carrier of the desired channel, to the RF OUTPUT jack on the rear
panel of the unit. Alternatively, connect a spectrum analyzer or a field strength
meter to the –20dB TEST POINT on the front panel of the unit.
2. Select the desired output channel using the CHANNEL SELECT paddle switch
on the front panel.
• Hold the CHANNEL SELECT switch in the up- or down-position for
approximately 3 seconds to activate the channel-select circuit;
• Toggle the CHANNEL SELECT switch up to select a higher channel
or toggle it down to select a lower channel. The switch may be held in
the up- or down-position for rapid channel switching.
3. Observe the output on the spectrum analyzer, or the field strength meter. If
measuring from the rear panel RF OUTPUT jack, adjust the front panel OUTPUT
LEVEL potentiometer for an output level between +55dBmV and +60dBmV. If
measuring from the front panel –20dB TEST POINT, ensure that the rear panel
RF OUTPUT jack is terminated into a 50Ω load, then adjust the front panel
OUTPUT LEVEL potentiometer for an output level between +35dBmV and
+40dBmV.
4. If using a field strength meter, retune the meter to the frequency of the audio RF
Carrier.
5. Still observing the output on the spectrum analyzer, or the field strength meter
(now tuned to the frequency of the audio RF carrier), adjust the front panel
AURAL CARRIER potentiometer for an output level 10-13dB lower than that at
which the video RF Carrier is set.
6. Remove the spectrum analyzer, or field strength meter from the unit. If available,
connect a television/monitor to the front panel –20dB TEST POINT, apply power
to the television/monitor and tune to the selected output channel of the
Technalogix TM-200 modulator.
TM-200 Issue 1.02 November 2005 Page 20 of 64
Setup of Video Input Connection and Adjustment
1. Connect a 1.0V
video source to the VIDEO IN jack on the rear panel.
P-P
2. Adjust the front panel VIDEO MODULATION control for 87.5% modulation.
• Set the front panel DISPLAY SELECT switch to VIDEO (down)
position;
• Observe front panel LED bar graph behind front panel display readout
window.
• First RED LED will begin illumination at approximately 87.5%
modulation; or
• Observe TV monitor for good visual image.
TM-200 Issue 1.02 November 2005 Page 21 of 64
Setup of Baseband Audio Input Connection and Adjustment
1. If your Technalogix TM-200 agile modulator is equipped with a 4.5MHz subcarrier input option, ensure that the rear-panel AUDIO SELECT switch is in the
BASEBAND position.
2. Connect a 1V
baseband audio signal to the rear panel baseband audio
P-P
connector as follows:
• For balanced input connection, connect one audio input lead to the
left terminal on the connector and the other audio input lead to the
right terminal.
• For unbalanced input connection, connect one audio input lead to the
left terminal on the connector and the other audio input lead to the
center terminal.
• Center terminal is chassis ground.
• Insert the terminal into the connector on the rear panel of the TM-200.
3. Adjust the front panel AUDIO MODULATION control for 100% modulation.
• Set the front panel DISPLAY SELECT switch to AUDIO (up) position.
• Observe front panel LED bar graph behind front panel display readout
window.
• First RED LED will begin illumination at approximately 95%
modulation; or
• Adjust for ±25KHz deviation using a spectrum analyzer; or
• Listen to the audio output from TV monitor and setting the loudness
equal to that of an off-air channel carried on your system.
TM-200 Issue 1.02 November 2005 Page 22 of 64
Setup of 4.5 MHz Sub-Carrier Audio Input Connection and Adjustment
1. Set the rear panel AUDIO SELECT switch in the 4.5 position.
2. Connect a modulated 4.5MHz sub-carrier signal to the rear panel 4.5MHz input
F-connector jack.
3. Inject a minimum +36dBmV (-12.75dBm) 4.5MHz RF carrier into the unit.
4. Using the setup in Step 5, Setup of Output Level and Channel Selection,
measure the audio RF carrier output level at the rear panel RF OUTPUT jack.
Level should be within ±2dB of the measurement taken in Step 5, Setup of Output Level and Channel Selection.
TM-200 Issue 1.02 November 2005 Page 23 of 64
Setup of IF Pre-Correction on Signal Conditioning PCB
Varying these two pots can increase and dec
rease the
1. Install the modulator but do not apply power yet.
2. Ensure that the two IF pre-correction potentiometers on the front panel of the
modulator are turned fully counter clockwise.
3. With the transmitter and modulator fully installed, apply power and bring the
transmitter up to rated power.
4. Apply a red field test signal to the input of the modulator with the aural carrier
turned on.
5. Take a sample of the RF output and view it on a spectrum analyzer.
6. Looking at the +/- 920kHz intermodulation products, adjust the two IF pre-
correction potentiometers to obtain the lowest level on the intermodulation
products.
output power, so this should be carefully monitored.
TM-200 Issue 1.02 November 2005 Page 24 of 64
Setup of Sync Level on Signal Conditioning PCB
Varying these two pots can increase and decrease the
1. With the transmitter at rated power and an NTC7 Composite signal applied
to the input of the modulator, view the demodulated waveform on a waveform
monitor.
2. Adjust the sync level potentiometer on the front panel clockwise for more sync or
counter clockwise for less sync to obtain 40 IRE of sync.
3. Maintain the white bar level at 100 IRE by adjusting the video modulation
potentiometer on the front panel.
output power, so this should be carefully monitored.
TM-200 Issue 1.02 November 2005 Page 25 of 64
Automatic Shut Down
Technalogix power supplies are designed so that under certain power line or heat
buildup conditions, the unit shuts off. An indicator would be no RF output, but the
POWER LED remains on. If this occurs, unplug the power cord and wait two minutes
before re-powering. Upon applying power, you should again have RF output. If not, or
should the unit return to shutdown mode, please contact Technalogix for assistance.
Technalogix highly recommends a 1.75 inch air circulation space between any rack
mounted equipment.
TM-200 Issue 1.02 November 2005 Page 26 of 64
Transmitter Hookup
1. Connect modulated video from TM-200 RF OUT to the Technalogix power amplifier.
2. Turn down RF level on TM-200 all the way.
3. Ensure that IF OUT is connected to IF IN on the TM-200 modulator using the loop F
to F cable supplied. If the IF pre-correction circuit is to be used, simply jumper 75ohm coaxial from the IF PRE-CORRECTION - IN to the OUTPUTS – VIDEO and
jumper from IF PRE-CORRECTION – OUT to the INPUTS – VIDEO connection.
4. Connect the transmitting antenna cable to the RF output connector on the power
amplifier. It is recommended that a quality through line wattmeter be installed in this
same line.
5. Verify that all signal and RF cables are connected properly.
6. After following proper installation procedures outlined in the power amplifier manual,
plug the power amplifier’s power cords into an appropriate electrical outlet.
Output power should be adjusted with a sync and blanking signal only with the aural
carrier removed. This is simply done by disconnecting one end of the audio carrier loop
found on the back panel of the TM-200.
TM-200 Issue 1.02 November 2005 Page 27 of 64
6.0 P
ROBLEM TROUBLESHOOTING GUIDE
The guide below covers some typical symptoms, possible associated causes and
suggested actions to follow before returning the unit for repair. It is not meant to be allinclusive.
Symptom Possible Cause Suggested Action
No output or weak output Baseband input level too weak Ensure proper 1 Vp-p video signal
present on input
IF loop cable on rear of unit loose
or disconnected
Unit not plugged in or getting AC
power
Unit tuned to output channel
different from desired (this occurs
particularly on the units which
have green LED on the front
panel to indicate “T” channels and
channels above 99)
Loss of video on the input – video
detect turned off RF Output
Excessive noise or spurious
signals
IF level too high (most often
Input signal too strong or no input
Bad/noisy video Aural carrier interfering with video
Channels do not change Delay feature active Hold channel change switch in
Output level above rated
maximum (most often occurs
when changing from high-number
channel to low-number channel,
especially to the “T” channels)
occurs when routing IF through
scrambler or other external
device)
signal at all
carrier
Check IF loop cable is securely
attached
Check power cord and power source,
fuse
Ensure selected output channel is
desired channel
Ensure proper 1 Vp-p video signal
present on input
Measure RF output from rear
panel jack and adjust front panel
OUTPUT LEVEL control as
required
Measure normal IF output level
for applied CW/unmodulated input
carrier and ensure same level is
returned to unit after external
processing
Measure video level and pad to
within specified input levels.
Measure Aural Carrier level
and/or adjust AURAL CARRIER
LEVEL control on front panel
raised/lowered position for at least
three seconds