[Amps] 3-500Z cool down time

[Gary Schafer]

Well, the plate is in a vacuum so no heat is conducted to the glass envelope
except for the small plate lead pin. All the air in the world isn't going to
cool the plate down.

Forced air on the tube is to keep the seal temperature down. 
All of the cooling of the plate is accomplished by radiation.

I believe that it would take a long time to heat up the plate with just the
filament on.

73
Gary  K4FMX

> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Clark
> Turner
> Sent: Monday, June 05, 2017 10:21 AM
> To: amps at contesting.com
> Subject: [Amps] 3-500Z cool down time
> 
> 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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