7400 нет передачи на КВ, есть на УКВ
при этом при попытке передачи на КВ нет показаний ни ALC, ни мощности, ни КСВ. на УКВ все работает правильно только в FM.
В сервис мануале описано прохождение сигнала:
4-2-6 RF CIRCUIT (RF AND PA UNITS)
The RF circuit amplifies operating (transmitting) frequency
to obtain 100 W of RF output.
The signal from the 1st IF mixer is passed through one of the
low-pass or bndpass filters (Refer to page 4-1 for bandpass
filters used) and high-pass filters after passing through the
low-pass filter (RF unit; L285, L286, C286–C289, C291).
The filtered RF signal is amplified at the wide-band YGR
amplifier (RF unit; IC151), and is then applied to the PA unit
via J151.
The signal applied from the RF unit is amplified at the 2 predrive
(PA unit; Q1, Q2) and drive (DRV board; Q1, Q2) amplifiers.
These amplifiers cover all HF, 50 MHz and 144 MHz
band amplifying operation.
When operating on the HF or 50 MHz band, the signal from
the drive amplifier is power amplified at the HF/50 MHz
power amplifier (PA unit; Q5, Q6) via the band switching relay
(PA unit; RL2). However, the 144 MHz signal is power amplified
at the 144 MHz power amplifier (PA unit; Q201, Q202)
to obtain a stable 100 W of RF output power.
The amplified signal is applied to the desired antenna connector
via one of 8 low-pass filters.
получается все цепи общие вплоть до (PA unit; Q1, Q2) and drive (DRV board; Q1, Q2) amplifiers и неисправность нужно искать в цепи оконечника?
