Hello,
Since I am much less knowledgeable about high voltage
amplifiers than low voltage digital design, I am hoping
some of you can help with a problem on my SB-200 linear.
Whenever I key the SB-200 with my transceiver, I see
varying degrees of blue flashes on both 572B tubes.
At very low drive levels (10W), I see a blue tint on two
sides of both tubes. At high drive levels, blue flashes
actually jump through the top of the SB-200 chassis,
providing for quite a light show.
Could someone please explain to me what is happening,
and if it is likely to be bad tubes, or if another part of the
SB-200 is likely to be causing this damage?
Some details:
-The same result occurs on multiple bands. I have tried
10, 15, and 20m so far. The band switch is not charred like
any of the ones shown on AG6K's web page.
-This started happening after the amplifier and tubes
traveled from one DXpedition to another.
-The tubes are matched Svetlana 572Bs from RF Parts,
were purchased about two years ago, and in that time, they
have a total keydown time of approximately 100 hours.
I suspect that I have damaged the 572Bs while traveling,
but before blindly purchasing another pair, I wanted to ask
for this reflector's expert advice.
Thanks in advance for any explanations and assistance you
can give me.
73...
-Dean - N6DE
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