[TenTec] Problem with carrier on LSB on my Omni 6+

[Ken Brown]

Hi Ernie,

     There are two differences between USB and LSB that could explain 
why the carrier is worse on one mode. The BFO (or carrier oscillator) 
changes frequency when you change sidebands. If the carrier balance is 
adjusted for the best null at one BFO frequency, it may not be as good a 
null at the other frequency. I doubt that difference is very much, 
probably only a few dB at most and not tens of dB. The other is the 
slopes of the crystal filter skirts are not exactly the same on the high 
frequency side and the low frequency side of the filter bandpass. Also 
the position of the BFO in relation to the filter skirts is not 
identical on both sidebands. The net result of all of those factors 
makes the carrier reduction different on opposite sidebands. My guess is 
that if you get the instability of the modulator balance fixed, it won't 
matter anymore.

DE N6KB

   theErnie Popp wrote:
> Omni 6+
> During CQWW ssb contest, I noticed that I had carrier present on LSB while operating on 40M. I checked and found it was present on all bands only on lower side band.  Upper seems fine. It seems more severe on 40m.  I first checked the 9mhz bfo crystal.  It was close and I fine tuned it a little.  This had no real effect and still had carrier on LSB. Next I adjusted  the  balanced mod.  I'm not sure if their is a special procedure for this.  I was able to completely eliminate the carrier.  After several day, the problem reappeared.  Once again, I adjusted the balanced mod to correct the problem.  Checking tonight it's back. I'm assuming that  something is unstable in the balanced mod circuit.  Why is USB not affected?  Has anyone experienced  this?  Any Ideas?
>
> Tnx,  Ernie K2EP
>
>
>
> k2ep at arrl.net
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