FT-857 low power on 6m

FT-857 low power on 6m

I have bought 5 years ago from a local om the ‘’fabulous’’ FT857 with a malfunctions of the microphone, the fabulous quartz filter and a low power in 6m band.

The microphone and the filter was repaired in russia and the 6m malfunction was discovered after the returned back of the transceiver.

After i repaired my ICOM IC746, i tried to repair the 6m problem as i taught the LPF or the relays are the responsables.

I took some larges copies of the schematics and PCB because the small dimension of the composants.

I removed the cable from J1002 and connected another to a wattmeter.

I found particaly 5 to 7 watts output unless in 6m.Following the scematic i found that there is two pair of diodes acting as a swith between the HF lpf and 6m bpf.

There is also a low level command coming from the PLL board to proper filter to function.

Please any help YAESU or from any one who have the same problem.
Very thanks in advance for your help.
It will take long time before i can find the solution. Too small for my eyes.

73s de CN8LI/SAID

My email is : cn8li  yahoo  fr