[Amps] 3-500Z cool down time

Kim Elmore cw_de_n5op at sbcglobal.net
Mon Jun 5 11:44:16 EDT 2017


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 at 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 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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