> Not really,
>
> its quit common that tubes like YL1050, TH347 etc. which
> are very high gain
> metal ceramic tetrodes for linear mode of small
> tv-transmitters and linear
> service arc internally from time to time.
> It does not matter whether they are new out of the box or
> being in service
> for a long time.
> Those tubes are extremely expensive and nobody throws them
> away.
> Everybody uses the circuitry in the power supplies which
> the manufactory
> suggests and never a grid fuse or grid resistor but direct
> ground
> connection.
> The YL1056 in my 2m amp is running now perfectly for
> almost 20 years with
> regular arcs even in standby, it does not matter at all,
> the P/S quickly
> resets and during a contest I do not loose any qso by
> that.
>
> 73
> Peter
Thanks Peter,
I was sure anyone with experience in manufacturing new PA's
with power grid tubes would know this, but maybe some do
not. I guess it is good to repeat it.
If I tossed back 3CX3000A7's that arced when brand new,
about 50% would go back. Those very same tubes, once
"burped" a few times, give many many years of service. This
is really common with many tube types in many classes of
service.
If it wasn't a problem, the factory would not put active
getters in large power grid tubes!
73 Tom
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