[ICOM] Frequency Jump on SSB by IC-271A

[ma.locksmith at juno.com]

I'd suggest looking in the vicinity of the BFO oscillator, Q6/Q7

They use a single crystal which is diode switched with inductors in
series to change the BFO frequency by using the mode switch setting.

There doesn't appear to be a difference in frequency for SSB (other than
USB vs LSB) but there is an 800 Hz offset for CW transmit.....  higher.

The frequencies (MHZ) you ought to see at R71 are

USB 10.7485
LSB  10.7515
CW-R  10.7485
CW-T  10.7493

You might be getting a leaky diode....  could confirm if offset is not
1000 but 800 Hz.

Ed
K1ZOK


On Sat, 21 Oct 2006 21:20:11 -0500 "crawfish" <crawfish at surfmore.net>
writes:
> I have a very annoying problem with my IC-271-A on 2m SSB. After 
> about 5 or 10 minutes, the transmit frequency jumps 1 kHz up(receive 
> frequency stays the same). Any ideas as to what is going on, and any 
> ideas on what might be causing it?I haven't heard any complaints on 
> FM.
>                                                       Joe W4AAB
>