On Wed, 2008-12-03 at 23:52 -0500, Phil Chambley Sr. wrote:
> Ernie....
>
> You say you had the carrier completely eliminated, and it re-appeared. How
> are you measuring? Do you use a scope, a wattmeter or a report from
> another ham?
And a little bit of hum in the audio like from the microphone hearing a
fluorescent light ballast can appear to be carrier. Or worse, an
intermittent shield connection on the microphone cable, usually at the
plug into the radio...
73, Jerry, K0CQ
>
> I've found it easier to listen on another receiver while adjusting the
> balanced mod trimpots. Even if you also use a scope you can hear the
> "bottom fall out" of the carrier. Be sure you have the microphone gain all
> the way off when doing this. Also, the two trimpots interact, so it is
> necessary to go back and forth repeatedly when adjusting them.
>
> With the CA3053 balanced modulator and a ladder filter, you won't ever make
> the carrier "completely disappear" on both sidebands...much less at the same
> time. But you can reach optimum by switching back and forth between USB and
> LSB while making the adjustments, so you get to a happy medium.
>
> Again, this is facilitated by listening slightly off frequency with another
> receiver.
>
> 73
> Phil C. Sr.
> k4dpk
>
> ----- Original Message -----
> From: "Ernie Popp" <k2ep@nycap.rr.com>
> To: <tentec@contesting.com>
> Sent: Wednesday, December 03, 2008 8:40 PM
> Subject: [TenTec] Problem with carrier on LSB on my Omni 6+
>
>
> > 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
> >
> >
> >
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|