Thanks Carl.
I will take Geralds advice as I have both a 5200 V supply and a Tripplet
630.
I received the tubes from a Navy MARS friend quite a while back who had big
ideas for them and no sockets.
I thought about getting an old HT-33, but with 3 sockets and more Ep I can
do better.
John WA4EPI
----- Original Message -----
From: "Carl" <km1h@jeremy.mv.com>
To: "John Finner" <finnerjf@worldnet.att.net>; <amps@contesting.com>
Sent: Saturday, January 16, 2010 9:09 AM
Subject: Re: [Amps] 4CX300a Seal Leaks
> Ive no idea if any date code could be considered good or bad John.
>
> My only experience with them was in a couple of HT-33's that were in for
> service decades ago and then I was told the reason for premature failures
by
> a few of the VHF amp builders..
>
> The USAF was a large user and they regularly surplused off stock after so
> many years so they didnt get caught with a problem. If you notice, NOS
> 300's are everywhere.
>
> Geralds idea is a good one that can be built also with PS components on
hand
> for the proposed project.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "John Finner" <finnerjf@worldnet.att.net>
> To: <amps@contesting.com>
> Sent: Friday, January 15, 2010 9:08 PM
> Subject: [Amps] 4CX300a Seal Leaks
>
>
> >I read a post by Carl, KM1H on August 10, 2009 that read:
> >
> > There are several ceramic tubes that are notorious for seal leakage. The
> > 4CX300A is a classic.
> >
> > This post is directed to Carl. The list might also be interested. I
would
> > be interested in a brief explanation of the problem.
> >
> > I have 7 NOS JAN 4CX300A's an am building a 3 tube passive grid driven
> > amp. The date codes are 7204, 7432 and 7634 if this makes a difference.
> > Are the JAN Eimac tubes less problematic?
> >
> > The amp is in a simibreadboard state with 4CX250B's. Since I now have 3
> > sockets for the 4CX300A's, I will switch tubes and raise the Ep to 2500
V.
> > I do not want to waste my time if I am going to have a problem with this
> > change.
> >
> > John WA4EPI
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>
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