On 1/17/2011 3:10 PM, Jim Goudie wrote:
Hello all,
A tale of misfortune and fortune. And before I decide which way to go, I
thought I'd check and see if the symptoms ring any bells out there...
I was on the air with my Omni VI opt 3... I was switching bands fairly often,
and the last switch was to 160. I set the tuner, which for 160 produced a
rather sharp null. When I keyed the rig, the breaker tripped. That's odd, I
thought. I hadn't tripped the breaker like that in many, many moons.
Shortening the story, after resetting the breaker, I found it would trip as
soon as the output power got up over a watt or two.... And it did it on 80
meters... and 20 meters without the tuner in line. I shut down for the night.
Today, going into a dummy load, it put out power until about 50 watts out, and
then the needle on the power meter went erratic, but the breaker never tripped.
The side story& symptom are that last night, after fooling around, I realized
the rig wasn't receiving any signals. This morning, when I first turned it on, it
received ok. But, after doing my dummy load testing, the received signals were
gone again.
So... I pulled my trusty 544 off the shelf to replace the Omni VI at my
operating position... and operated for three hours with that.
I'm guessing the problem lies in the SWR-sensing, tx-rx switching stuff in the
output... I haven't cracked it open or even looked at the schematic yet...
Any thoughts?
I think that's the first place to look but be sure all the board grounds
are tight so that the PA or RF board isn't oscillation at some out of
band frequency.
I recall losing the diodes in the SWR sensing/ALC detect area has made
several TT radios do weird thiings.
73, Jerry, K0CQ
Jim, AF3Z
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