[Amps] 3-500Z cool down time

[Clark Turner]

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