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In this series of videos (8 episodes) you can watch the complete servicing and restoration of a multi-band, multi-mode transceiver, the Yaesu FT-767GX from the mid 1980’s (made in Japan). This model operates on HF (all bands) + 6 meter + 2 meter + 70 cm bands (6, 2 and 0.7 m bands depend on the optional modules installed). Output power is 100 W in HF and 10 W on the other bands.
First tests on the bench (reception and transmission). First overall cleaning. Opening the transceiver and performing maintenance on the power supply, power amplifier stage, low pass filter board and antenna tuner. PA idling current adjustment. Adjustment of the CM coupler balance on the LPF unit.
Antenna tuner adjustment and tests after maintenance. Antenna tuner variable capacitor servo adjustment, setting of the tuner stop SWR threshold and tuner auto-start SWR threshold. Repair of the main dial encoder (the repair was attempted by re-aligning the encoder, which resulted for a few days but proved not to be a reliable solution; the encoder had to be replaced, as explained in episode 7). Dismantling and in-depth cleaning of the front panel, buttons/knobs. Reassembly of the front panel.
Maintenance on the optional 6 meter (FEX-767-6) module and 2 meter (FEX-767-2) module. Cleaning and restoration of the desk microphone (Yaesu MD-1 C8).
Alignment/adjustment of the transceiver – Local Unit: Local oscillators, band-pass filters, 45 MHz TCXO, carrier oscillators, TX IF shift, FM carrier frequency, PLL sub-loop VCO, main loop VCO’s, local levels…
Alignment/adjustment of the transceiver – IF Unit: 8.67MHz oscillator frequency (RX and TX), 3rd local level, receiver IF transformers, IF gain, S-meter calibration, FM receive sensitivity, FM receive volume preset, discriminator center calibration, noise blanker IF and IF notch resonance.
Alignment/adjustment of the transceiver – RF Unit/Transmitter: ALC Meter zero threshold, transmitter IF transformers, ALC level, ALC meter sensitivity, PO meter calibration, automatic final protection (SWR turndown), digital SWR/Power meter calibration, transverter ALC level, VCC meter, SSB carrier balance, AM carrier level, speech processor balance, speech processor IF, FM modulation adjustment, AM IF monitor and monitor output level adjustment.
Reassembly, last minute repairs and bench testing. After reassembly, a few intermittent faults were identified: the speech processor potentiometer and the VFO encoder, which had to be replaced (new components), and the fan motor which had a little play that had to be adjusted for quiet operation both in low and high speed. After solving these last-minute issues, the reception sensitivity and transmission power/ALC were tested on the bench.
Testing on-the-air and packing. Reception tests on the 40-meter and the 20-meter band. Making a contact on the 40-meter band (F5RAG). Protecting the equipment and packaging.
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