Ted -- I worked on a Titan that was doing this. The problem turned out
to be loose gold particles in the 3cx800s. The tubes were made useable
again by moving the loose gold into the tube bases by tapping the anode
caps and watching the anode-grid leakage current decrease on the
high-pot tester. When the leakage stops decreasing, I stop tapping.
// If you don't have access to a high-pot, I will test your tubes for
the price of return postage.
-- note -- The reason that the problem typically shows up with RF is
that since +V attracts gold particles, the more the anode-V swings
positive with a signal, the stronger the attraction of the gold to the
anode. When too many gold particles get sucked up onto the anode-grid
insulator, the amplifier will shut down.
good luck
On Nov 24, 2004, at 7:27 PM, TED & JOYCE wrote:
Hi All,
Just found this reflector and hoping someone out there may have an
answer short of new tubes to my problem.....Am running an Kenwood 870
into an Alpha 87a (about 5 years old)......On phone there is now
problem with putting out full power...once I go to CW if I drive it
and output is over about 5-600 watts it just completly shuts
down.....NO deffaults lites or anything.....Talked with alpha one
time about this and they told me tubes were getting soft which I am
sure they are.......Short of putting 6Bills in to some new tubes is
there any suggestions to get around this intial volatage strike to the
amp from the exciter... and if it is necessary to retube is there any
way to avoid these kind of problems in the future......Yes before
anyone replies it is not in feed lines antennas etc etc.........Same
freq. same everything fine on SSB intial spike on CW turns it
off............Thanks and hoping to hear from somebody that has been
down this road before................Best of 73"s and a very Happy
Thanksgiving too all...........
Ted K9HUH "huh:
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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