"Dave Hall" wrote in message
...
On Tue, 15 Feb 2005 09:57:06 -0500, Vinnie S.
wrote:

While I solved one problem on SSB, another continues.


I am still having that "carrier" problem on SSB. For some reason, as soon
as
I speak into the mic, the radio holds power, as if it were on AM. The TX
meter
on the radio shows this, and the SWR/power meter shows this. The power is
not
fluctuating with modulation. The ALC was not cranked up. The power is not
high,
about 20 watts peak. Like I said, it seems to do this as soon
as I speak into the mic. Even a subtle noise will send it to max, and stay
there. Changed mics, and have the same problem.

So then I tried this.

I took this radio and put it in my car (it's my only radio). When I
connect it
directly to the Wilson 1000 barefoot, I get the same problem on SSB.
However,
when I go thru the amp, it works perfectly, no power unless I modulate.
This is
also true if the amp is turned on or off. It appears to be an impedance
mismatch. Since the amp input is a perfect match, the problem goes away,
whether
or not the amp power is on or off. Here is the kicker. The SWR on my home
antenna is about 1.3-1.5 across the band.

The final oscillation is most definitely related to output load
impedance. When I first stumbled onto this problem (In some older dual
final Galaxy radios), the problem would never show up on the bench
when I used my dummy load. It also didn't show on my base antenna. But
the problem would happen on the customer's antenna. I managed to force
the problem on my antenna by using a tuner and de-tuning the match
until the oscillation occurred.

The cover of the radio acts like a capacitor, and it's very sensitive
to it.

Did you see any bottom mounted caps connected to the final
transistor? If not then you might have to mount a piece of grounded
shield plate over the final or experiment with bypass caps until you
kill the oscillation. But try setting the bias first. If I remember
right, the bias for the final should be set at somewhere in the 30 -
40 mA range. I'll check the manual and give you the exact value.

Dave
"Sandbagger"

I kinda figured oscillation also. Bad bias can cause it. Make sure that's
correct. See if any one had hinkeyed around in there, Check serial
numbers, did these not use 2 different finals at different times? When
changing finals did they change drive components? Unfortunately I do not
have a schematic here to look around. Did anyone do any "coil spreading"?

Chad