Toshiba FT-2800M Service Manual

FM TRANSCEIVER

FT-2800M

Technical Supplement

VERTEX STANDARD CO., LTD.

4-8-8 Nakameguro, Meguro-Ku, Tokyo 153-8644, Japan

VERTEX STANDARD

US Headquarters

10900 Walker Street, Cypress, CA 90630, U.S.A.

International Division

8350 N.W. 52nd Terrace, Suite 201, Miami, FL 33166, U.S.A.

YAESU EUROPE B.V.

P.O. Box 75525, 1118 ZN Schiphol, The Netherlands

YAESU UK LTD.

Unit 12, Sun Valley Business Park, Winnall Close Winchester, Hampshire, SO23 0LB, U.K.

VERTEX STANDARD HK LTD.

Unit 5, 20/F., Seaview Centre, 139-141 Hoi Bun Road, Kwun Tong, Kowloon, Hong Kong

PWR MHz REV LOW D/MR

Introduction

This manual provides technical information necessary for servicing the FT-2800M FM Transceiver. Servicing this equipment requires expertise in handling surface-mount chip components. Attempts by non-qualified per-

sons to service this equipment may result in permanent damage not covered by the warranty, and may be illegal in some countries.

Two PCB layout diagrams are provided for each double-sided circuit board in the Transceiver. Each side of is referred to by the type of the majority of components installed on that side (“leaded” or “chip-only”). In most cases one side has only chip components, and the other has either a mixture of both chip and leaded components (trimmers, coils, electrolytic capacitors, ICs, etc.), or leaded components only.

While we believe the technical information in this manual to be correct, VERTEX STANDARD assumes no liability for damage that may occur as a result of typographical or other errors that may be present. Your cooperation in pointing out any inconsistencies in the technical information would be appreciated.

Specifications..................................................... 2

Exploded View & Miscellaneous Parts........... 3

Block Diagram .................................................. 5

Circuit Description .......................................... 7

Alignment .......................................................... 9

Board Unit (

µCOM Unit /RF Unit Circuit Diagram ..........................13

µCOM Unit Parts Layout .............................................. 15

µCOM Unit Parts List ................................................... 17

RF Unit Parts Layout .....................................................21

RF Unit Parts List ..........................................................23

Schematics, Layouts & Parts

)

Specifications

General

Frequency Range: Tx 144 - 146 MHz or 144 - 148 MHz

Rx 144 - 146 MHz or 137 - 174 MHz

Channel Step: 5/10/12.5/15/20/25/50/100 kHz Standard Repeater Shift: ±600 kHz Frequency Stability: Better than ±10 ppm [–4 °F to +140 °F (–20 °C to +60 °C)] Modes of Emission: F2/F3 Antenna Impedance: 50 Ohms, unbalanced Supply voltage: 13.8 V DC ±15%, negative ground Current Consumption (typical): Rx: less than 0.7 A, less than 0.3 A (squelched)

Tx: 10 A (65 W)/7 A (25 W)/5 A (10 W)/4 A (5 W)

Operating Temperature Range: –4° F to +140° F (–20° C to +60° C) Case Size (WxHxD): 6.3” x 2.0” x 7.3” (160 x 50 x 185 mm) (w/o knobs) Weight (Approx.): 4.0 lb (1.8 kg)

Transmitter

Output Power: 65 W/25 W/10 W/5 W Modulation Type: Variable Reactance Maximum Deviation: ±5 kHz/±2.5 kHz Spurious Radiation: Better than –60 dB Microphone Impedance: 2000 Ohms

Receiver

Circuit Type: Double Conversion Superheterodyne Ifs: 21.7 MHz & 450 kHz Sensitivity (for 12dB SINAD): Better than 0.2 µV Selectivity (–6/–60dB): 12 kHz/28 kHz IF Rejection: Better than 70 dB Image Rejection: Better than 70 dB Maximum AF Output: 3 W into 4 Ohms @10 % THD

Specifications subject to change without notice or obligation. Specifications guaranteed only within Amateur band

S8101427

CONNECTOR

(with BLADE FUSE)

S8002057

S8002059 CASE-FRONT

S8002062 BUTTON

S8002056 REFLECTOR

S8002060 FILTER-LCD

S8002061 CONNECT-LCD

S8101434 LCD

S8002055 PLATE-EARTH

µCOM Unit

CASE-MAIN

Exploded View & Miscellaneous Parts

S8101435 CABLE

S8002064 SPACER

S8002052 KNOB-VOL

S8002053

KNOB-DIAL

Screw List

REF. VXSTD P/N Description Qty.

U30308007 FLAT HEAD SCREW M3x8B 6

S8002065 BOLT CAP M3x20 BZC 3

S8002066 TAPTITE SCREW 3x8ZC 4

U44306001 TAPTITE SCREW M3x6 9

S8002067 TAPTITE SCREW 3x10ZC 8

S8002068 WASHER-PLAIN 2

RF ASSY

S8002058 COVER-BOTTOM ASSY

Accessories

Description VXSTD P/N FOOT S8002050 BRACKET S8002051 BLADE FUSE ATC 15A Q0000075 CABLE ND-A35-2500CB S8101436 MIC MH48A6J AAA43X001

S8002063 CAP-SP

S8101433 SPEAKER

Exploded View & Miscellaneous Parts

Note

Block Diagram

Note

Circuit Description

Reception and transmission are switched by “RX” and “TX” lines from the microprocessor unit (MPU). The receiver uses double-conversion superheterodyne circuitry, with a 21.7 MHz 1st IF and 450 kHz 2nd IF. The 1st local, produced by a PLL synthesizer, yields the 21.7 MHz 1st IF.

The 2nd local uses a 21.250 MHz (21.7 MHz - 450 kHz) signal generated by a crystal oscillator. The 2nd mixer and other circuits use a custom IC to convert and amplify the 2nd IF, and detect FM to obtain demodulated signals.

During transmit, the PLL synthesizer oscillates at the desired frequency directly, for amplification to obtain RF power output. During transmit, voice modulation and CTCSS (or DCS) modulation are applied to this synthesizer. Transceiver functions, such as TX/RX control, PLL synthesizer settings, and channel programming, are controlled using the MPU.

Receiver

Incoming RF signals from the antenna connector are delivered to the RF Unit, and pass through a lowpass filter (LPF) consisting of coils L303, L305, and L307, capacitors C303, C309, C310, and C316, and antenna switching diodes D305 and D306 (Both MA111) for delivery to the receiver front end.

Signals within the frequency range of the transceiver are then passed through a varactor-tuned bandpass filter consisting of diodes D308, D322, D310 and D323 (all HVC3508), and coils L334, L335, L320 and L322 and associated circuitry before RF amplification by Q316 (3SK240).

The amplified RF signal is then bandpass filtered again by varactor-tuned resonators consisting of diodes D312, D324, D313 and D325 (all HVC3508), and coils L336, L337, L325 and L327 and associated circuitry, to ensure pure in-band input to 1st mixer Q321 (3SK240).

The 2nd local in the IF-IC is produced from crystal X302 (21.250 MHz), and the 1st IF is converted to 450 kHz by the 2nd mixer and stripped of unwanted components by ceramic filter F302. After passing through a limiter amplifier, the signal is demodulated by the FM detector.

Demodulated receive audio from the IF-IC is amplified by Q336 (2SA1588Y) and Q338 (UMX2M). After volume adjustment by the AF power amplifier Q337 (LA4425A), the audio signal is passed to the optional headphone or 8-ohm loudspeaker.

PLL Synthesizer

The 1st local maintains stability from the PLL synthesizer by using a 21.250 MHz reference signal from crystal X301. PLL synthesizer IC Q333 (LV2105V) consists of a prescaler, reference counter, swallow counter, programmable counter, a serial data input port to set these counters based on external data, a phase comparator, and a charge pump.

The PLL-IC divides the 21.250 MHz reference signal by 4,250 using the reference counter (5.0 kHz comparison frequency). The VCO output is divided by the prescaler, swallow counter and programmable counter. These two signals are compared by the phase comparator and applied to the charge pump. A voltage proportional to their phase difference is delivered to the low-pass filter circuit, then fed back to the VCO as a voltage with phase error, controlling and stabilizing the oscillating frequency. This synthesizer also operates as a modulator during transmit.

The RX VCO is comprised of Q323 (2SC5006) and D314/D326 (Both 1SV282), and oscillates at 21.7 MHz during receive.

The TX VCO is comprised of Q322 (2SC5006) and D316/D327 (Both 1SV282) and oscillates at the funda- mental frequency during transmit, with direct frequencymodulation using varactor diode D315 (1SV214).

Buffered output from the VCO Unit is amplified by Q318 (2SC5006) and lowpass-filtered by L339, C414, and C413, to provide a pure 1st local signal between 112.3 and 152.3 MHz, which is delivered to the 1st mixer.

The 21.7 MHz 1st mixer product then passes through dual monolithic crystal filter F301 (7.5 kHz BW), and is amplified by Q327 (2SC4215Y) and delivered to the input of the FM IF subsystem IC Q334 (TA31136FN).

This IC contains the 2nd mixer, 2nd local oscillator, limiter amplifier, FM detector, noise amplifier, S-meter amplifier and squelch gates.

The VCO output passes through buffer amplifier Q320 (2SC5005), and a portion is fed to the PLL IC, and at the same time is amplified by Q318 (2SC5006) to obtain stable output. Synthesizer output is fed to the 1st mixer by diode switch D311 (1SS321) during receive, and to pri-drive amplifier Q317 (2SC3356) for transmit.

The reference oscillator feeds the PLL synthesizer, and is composed of crystal X301 (21.250 MHz) and transmit (DCS) modulation circuit D317 (HVC350B).

The VCO DC supply is regulated by Q330 (2SC4617).

Circuit Description

Transmitter

The speech signal from the microphone is delivered via the MIC Jack to the RF Unit; after passing through Q315 (NJM2902V) which consists of amplifier, pre-emphasis, limiter (IDC instantaneous deviation control) and lowpass filter, to Q319 (M6364FP) which is adjusted for optimum deviation level and delivered to the TX VCO Q322.

The speech signal from the microphone and CTCSS are FM modulated by the TX VCO of the synthesizer, while DCS audio is modulated by the reference frequency oscillator of the synthesizer.

Synthesizer output, after passing through diode switch D311 (1SS321), is amplified by pri- drivers Q317 (2SC3356) and Q314 (RD00HVS1), driver Q313 (2SK3075), and power amplifier Q305 (RD70HVS1) to obtain full RF output. The RF energy then passes through antenna switch D303 (XB15A407) and a lowpass filter circuit and finally to the antenna connector.

RF output power from the final amplifier is sampled by

C318 and C324 and is rectified by D302 (1SS321). The resulting DC is fed through Automatic Power Con-

troller Q309 (UMT1N), Q312 (DTC114), and Q311 (2SB1197) to transmitter RF amplifier Q305 and is used to provide control of the power output.

Generation of spurious products by the transmitter is minimized by the fundamental carrier frequency being equal to the final transmitting frequency, modulated directly in the transmit VCO.

Additionally harmonic suppression is provided by a lowpass filter consisting of L303, L305, C303, C309, C310, and C316, resulting in more than 60 dB of harmonic suppression prior to delivery of the RF

Alignment

Introduction and Precautions

The FT-2800M has been carefully aligned at the factory for the specified performance at the 144 MHz amateur band. Realignment should therefore not be necessary except in the event of a component failure. All component replacement and service should be performed only by an authorized Vertex Standard representative, or the warranty policy may be voided.

The following procedures cover the sometimes critical and tedious adjustments that are not normally required once the transceiver has left the factory. However, if damage occurs and some parts are replaced, realignment may be required. If a sudden problem occurs during normal operation, it is likely due to component failure; realignment should not be done until after the faulty component has been replaced.

We recommend that servicing be performed only by authorized Vertex Standard service technicians who are experienced with the circuitry and fully equipped for repair and alignment. Therefore, if a fault is suspected, contact the dealer from whom the transceiver was purchased for instructions regarding repair. Authorized Vertex Standard service technicians realign all circuits and make complete performance checks to ensure compliance with factory specifications after replacing any faulty components.

Those who do undertake any of the following alignments are cautioned to proceed at their own risk. Problems caused by unauthorized attempts at realignment are not covered by the warranty policy. Also, Vertex Standard must reserve the right to change circuits and alignment procedures in the interest of improved performance, without notifying owners.

Under no circumstances should any alignment be attempted unless the normal function and operation of the transceiver are clearly understood, the cause of the malfunction has been clearly pinpointed and any faulty components replaced, and the need for realignment determined to be absolutely necessary.

Required Test Equipment

The following test equipment (and thorough familiarity with its correct use) is necessary for complete realignment. Correction of problems caused by misalignment resulting from use of improper test equipment is not covered under the warranty policy. While most steps do not require all of the equipment listed, the interactions of some adjustments may require that more complex adjustments be performed afterwards. Do not attempt to perform only a single step unless it is clearly isolated electrically from all other steps. Have all test equipment ready before beginning, and follow all of the steps in a section in the order presented.

r Regulated DC Power Supply: adjustable from 10 to

17 VDC, 15 A

r RF Signal Generator with calibrated output level at

200 MHz

r Frequency Counter: ±0.1 ppm accuracy at 200 MHz r AF Signal Generator r SINAD Meter r Deviation Meter (linear detector) r AF Milivoltmeter r AF Dummy Load: 8-Ohm, 5 W r DC Voltmeter: high impedance r Inline Wattmeter with 5% accuracy at 200 MHz r 50-Ohm non-reactive Dummy Load: r 100 watts at 200 MHz r VHF Sampling Coupler

Set up the test equipment as shown for the transceiver alignment, and apply 13.8 VDC power to the transceiver.

Alignment Preparation & Precautions

A dummy load and inline wattmeter must be connected to the antenna jack in all procedures that call for transmission, except where specified otherwise. Correct alignment is not possible with an antenna. After completing one step, read the following step to determine whether the same test equipment will be required. If not, remove the test equipment (except dummy load and wattmeter, if connected) before proceeding.

Correct alignment requires that the ambient temperature in the repair shop be the same as that of the transceiver and test equipment, and that this temperature be held constant between 68 oC and 86 oF (20 oC ~ 30 oC). When the transceiver is brought into the shop from hot or cold air it should be allowed some time for thermal equalization with the environment before alignment. If possible, alignments should be made with oscillator shields and circuit boards firmly affixed in place. Also, the test equipment must be thoroughly warmed up before beginning.

Notes: Signal levels in dB referred to in alignment are

based on 0 dBµ = 0.5 µV.

Alignment

Entering the Alignment mode

Alignment of the FT-2800M is performed using a frontpanel software-based procedure. To perform alignment of the transceiver, it must first be placed in the “Alignment Mode,” in which the adjustments will be made and then stored into memory.

To enter the Alignment mode:

1. Press and hold in the [LOW] key and [D/MR] key while turning the radio on. Once the radio is on, release these two keys.

2. Press and hold the [MHz] key for one second to activate the “Set” (Menu) mode.

3. Rotate the DIAL knob to select “35 D/ASMT,” then press the [MHz] key.

4. You will now note the appearance of “REF” on the display, this signifies that the transceiver is now in the “Alignment mode.”

PLL Reference Frequency (REF)

1. Tune the transceiver to 146.000 MHz.

2. Set the transceiver to Alignment mode, then rotate the DIAL knob to set the Alignment parameter to “REF.”

3. Press the PTT switch to activate the transmitter, and press the [REV] or [D/MR] key, as needed, so that the counter frequency reading is 146.000 MHz.

4. Press and hold the [LOW] key for one second to save the new setting.

5. Press and hold the [MHz] key for one second to exit to the normal operation.

PLL VCO

1. Connect the DC voltmeter to TP-RVC on the RF Unit.

2. Tune the frequency to 146.000 MHz.

3. Adjust L330 on the RF Unit for 1.5 V on the DC volt-

meter.

4. Connect the DC voltmeter to TP-TVC on the RF Unit.

5. Press the PTT switch to activate the transmitter, and adjust L329 on the RF Unit for 1.3 V on the DC voltmeter.

RF Front-end Tuning (TUN137/TUN146/TUN160/TUN173)

1. Connect the DC voltmeter to the Test Point (RSSI: Pin 6 of J307) on the RF Unit.

2. Tune the transceiver to 137.050 MHz.

3. Set the transceiver to Alignment mode, then rotate the DIAL knob to set the Alignment parameter to “TUN137.”

4. Inject a 137.050 MHz signal at a level of –5 dBµ (with 1 kHz modulation @ ±3.5 kHz deviation) from the RF Signal Generator.

5. Press the [REV] or [D/MR] key for maximum deflection of the DC voltmeter.

6. Press and hold the [LOW] key for one second to save the new setting, then press and hold the [MHz] key for one second to exit to the normal operation.

7. Tune the transceiver to 146.050 MHz.

8. Set the transceiver to Alignment mode, then rotate the DIAL knob to set the Alignment parameter to “TUN146.”

TP-RVC

L329

RSSI

TP-TVC L330

RF UNIT ALIGNMNT POINTS

+ 22 hidden pages

Toshiba FT-2800M Service Manual

Introduction

Contents

Specifications

Exploded View & Miscellaneous Parts

Block Diagram

Circuit Description

Receiver

PLL Synthesizer

Transmitter

Alignment

Introduction and Precautions

Required Test Equipment

Alignment Preparation & Precautions

Entering the Alignment mode

PLL Reference Frequency (REF)

PLL VCO