[ICOM] Icom 765 - loss of audio & transmit !

[Gary P. Fiber]

Could be a trimmer or the VCO is unlocked would be my guess. There is a 
voltage that is switched to turn on the VCO in use, might have a look at 
that when the problem is there.
 If it were the LPL loop then the dead spots would repeat every few kHz 
all they way through the tuning range of the 765. Both are voltage 
measurements.It would not hurt to check both and the rest of the VCO 
alignment while he is looking at the PLL board.

Gary K8IZ

Will (by way of Dick Flanagan <dick at k7vc.com>) wrote:
> I own a fairly late model ICOM 765. About 2 years ago I replaced the 
> VCO trimmers; these were bought direct from Icom UK as I was 
> experiencing many of the symptoms related to the need to replace 
> them. Raspy SSB audio etc etc.   I was, at the time, not convinced 
> that the replacement trimmers were of the ceramic type but, after a 
> call to their head office in Kent, England, I was assured that they 
> would do the trick. The replacement procedure went without a hitch 
> and all has been well since.  The past few days I have had the 
> following experiences. When I switch the rig on, I more or less 
> immediately lose any audio and am unable to transmit on 7 Mhz or 
> below. Switching bands up to 10, 14, 21 Mhz etc both transmit and 
> receive is fine but when I go back to 7, 3.5 or 1.8 Mhz, I cannot 
> hear a thing nor am I able to transmit.  I switch the rig off and 
> leave it for a while and, on a intermittent basis, when I switch it 
> on again, I can transmit and receive on 7 Mhz or below. The audio 
> then fails as does the ability to transmit. There is definately an 
> intermittent fault, be it a dry joint or a dodgy bit of switching on 
> the bands mentioned. I think I may have a faulty VCO trimmer but has 
> anyone else experienced this. In particular, the fact that it is only 
> affecting 7 Mhz and below ???  kind regards Will / GM0HKS
>
>