SB-102 Problem...!!!!!

[Kenneth G. Gordon]

On 26 Jul 2009 at 16:27, Alexander N. Gerli Sr. wrote:

> Hi, gang!

Hello, Andrew

> Had a nasty surprise this afternoon. Went to tune up the SB-102 for
> the Heathkit Net on 20M and the USB position of the MODE switch seemed
> flaky. Tons of rx and tx in LSB and TUNE, but USB rx was quite
> attenuated and so was CW. No mic gain either in USB, but tons in LSB.
> 
> Somehow, I doubt that the MODE switch is flaky; I've cleaned all the
> pots and switches in the past two months. Since I'm usually on 75 and
> 40M, I didn't notice that anything was necessarily wrong until this
> afternoon. Sure tuned up fine in TUNE.
> 
> I'm wondering if the USB xtal might be at fault, as the rx is pretty
> poor as well.

The USB crystal is used for transmitting in both USB and in CW....AND in 
TUNE.

So that would indicate to me that the USB crystal is OK.

There are three crystals used in the BFO and 2 different crystal 
oscillators: both halves of a 12AT7, if I remember correctly.

There is one crystal for LSB transmit and receive, one for USB transmit 
and receive and CW transmit, and for TUNE, and one for CW receive 
which is 1Khz away from the USB crystal.

If your transmitter is working properly in TUNE, then the USB/CW/TUNE 
transmit crystal is probably OK.

My first suspicion is the heterodyne oscillator settings for that particular 
band you are attempting to use USB on....

However, on second thought, that may not be the case either.

Have you ever attempted to use USB on 75 or 40, or are you using USB 
on a band that you do not normally use?

I would attempt to use USB on at least one of those two bands you 
normally use. Get a friend in your town to talk with you there.

If all is well there, then try LSB on 20 with that same friend.

I still suspect that your heterodyne oscillator settings or the crystal for 20 
meters is off.

Ken Gordon W7EKB

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