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

To: Gary Schafer <>, 'Clark Turner' <>,
Subject: Re: [Amps] 3-500Z cool down time
From: Joe <>
Date: Mon, 5 Jun 2017 12:28:32 -0500
List-post: <>
Plus in my amp if I ever got the plates hot enough to glow red or orange.
I'd say once RF is removed I bet it's less than a second that it's no longer colored, and not long after that what ever temp it is because of he filament. I'd say less than 5 seconds if that long!

The Original Rolling Ball Clock
Idle Tyme
On 6/5/2017 12:24 PM, Gary Schafer wrote:
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.

Gary  K4FMX

-----Original Message-----
From: Amps [] On Behalf Of Clark
Sent: Monday, June 05, 2017 10:21 AM
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?

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