My understanding is the graphite is dimensionally stable with temperature --
that's part of why graphite is used in aircraft dry vacuum pumps, which get
very hot. Thus, I don't buy that explanation.
I didn't have a graphite anode, but I only let mine cool for a couple of
minutes for the sake of the glass seals.
Kim N5OP
"People that make music together cannot be enemies, at least as long as the
music lasts." -- Paul Hindemith
> On Jun 5, 2017, at 10:35, Richard Solomon <dickw1ksz@gmail.com> wrote:
>
> 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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