[TenTec] Omni 6+ - no output on 12M/10M and omni 6+/ power issue

[Dr. Gerald N. Johnson]

Low or no output on a band or bands can be dirty switch contacts. 10, 
12, and 15 haven't had much use in the past few year. It might be a 
quarter drop of deoxit on each contact with some vigorous switch 
operation might clean them up, or the problem could be a poor solder 
joint that went open or nearly open.

Low or missing LO drive kills the gain of a mixer. Low gain due to a 
problem in a bandpass filter after mixer also lowers the output on a 
band or two, not necessarily the highest band. And this applies to every 
stage that has band specific filtering. Its a little more isolated than 
low or no output on all bands because then every stage and every 
oscillator is suspect in the whole transmitter. So its signal line and 
LO mixer that needs checking.

A check for LO is to see if it receives with the same sensitivity on 
those bands where the transmit is low or missing.

Its not possible to be more specific because there can be so many ways 
to loose a band or bands (and the crystal is not above suspicion nor the 
crystal socket when crystals are used to heterodyne the VFO) unless one 
has repaired many Omni VI with the same problem. I doubt there's any RF 
difference between VI and VI+.

73, Jerry, K0CQ

On 11/27/2010 10:59 AM, Barry N1EU wrote:
> My Omni 6+ suddenly has zero power output on 12M/10M tested into a dummy
> load - all other bands fine.  Can someone point me in the direction of
> possible faults?
>
> Tnx/73, Barry N1EU
> _______________________________________________
>
On 11/27/2010 10:28 AM, Wayne W8AJU wrote:
> My OMNI 6+ has a power issue on 20m and 17m, it drops to 50w output on 20m and
> 15w on 17m. All other bands are okay.  I've checked the output of the L.O. Mixer
> board, port 26, across a 50 ohm load. 160m through 40m, the the output is 800
> mvpp and and drops to 100mv on 20m and up. I don't think it is the output
> filters of the PA  because 20m and 17m don't share the same filter. The L.O.
> Mixer is nested below another board so I can not make any measurements on that
> board other than ohm meter readings.  Has anyone seen this before?
>
> Thanks,
> Wayne/w8aju