[Amps] 3-500Z cool down time

[Carl]

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 at gmail.com>
To: "Amplifiers" <Amps at 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 at 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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