[ICOM] IC-751A USB problem

[Jaime Gomez]

I have a friend´s (HK1F) radio, an IC-751A with a strange problem. It
receives  and transmits OK on all modes and frequencies, except in USB. In
USB when I transmit the radio output frequency moves down 2 KHZ, the Rx
frequency is OK. I have checked transmitting with my IC-781 and it receives
right on frequency.

I did PLL and Frequency alignment as per the service manual and found the
USB BFO fequency out of range. I replaced the trimmer C202 and the frequency
is now right as per the manual and it does not change between Tx and Rx.

I adjusted the PBT and there is no change in frequency between Tx and RX. I
do not know what else can I check to find why that change of frequency in
USB transmission.

Appreciate any help, thank you and 73

-- 
Jim, HK1N