Re: [Amps] 3-500Z cool down time

["Carl" <km1h@jeremy.qozzy.com>]

Im happy to oblige.

The initial runs had graphite plates and were made by Philips until Eimac 
got their act together. Early SB-220's and other late 69 early 70 amps used 
them. Amperex (owned by Philips) suggested a short cool down period of a few 
minutes once they were using the Philips built ones which recently stopped 
production.

----- Original Message ----- 
From: "Richard Solomon" <dickw1ksz@gmail.com>
To: "Amplifiers" <Amps@contesting.com>
Sent: Monday, June 05, 2017 11:35 AM
Subject: Re: [Amps] 3-500Z cool down time


> IIRC, Eimac never made Graphite 3-500's,
> if I am wrong, someone will correct me.
>
> The Graphite Anode, being of larger mass,
> and who knows what's in them, may need
> those precautions.
>
> Saying that, I converted an old SB-220 to
> 6 Meters and never followed those precautions,
> even though both tubes had Graphite Anodes.
>
> But then, they were older tubes, years older.
> With today's tubes ....
>
> 73, Dick, W1KSZ
>
> On Mon, Jun 5, 2017 at 8:21 AM, Clark Turner <Clark@clarkturnertuning.com>
> wrote:
>
> > RF parts supposedly told a local ham that 3-500Z RF parts tubes need a
> > minimum of 30 Full minutes of cool down with the blower on and that they
> > also need to warm up.  He insisted they told him this information and 
> > said
> > that if you do not warm up for 5 to 10 min and cool down for 30, the
> > graphite will crack.
> >
> > 3-500z is an instant on tube and one of its largest advantages. I have
> > turned my SB220 on, Made contacts and shut it off for 20 years with Eimac
> > tubes.
> >
> > Do you agree with this information?
> >
> > C
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