I think my 813 worked 20years with 3500V 800W out on a single tube, ground
grid amplifier. The graphite plate got orange to yellow in few seconds any
time ptt was on and back to graphite color few seconds after ptt released.
I never told my 813 about the cracked problem, or it is some new precaution
from Chinese tube manufactures.
73
N4IS
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Clark Turner
Sent: Monday, June 05, 2017 1:30 PM
To: Gary Schafer <garyschafer@largeriver.net>; amps@contesting.com
Subject: Re: [Amps] 3-500Z cool down time
That makes sense to me Gary. I have never heard of cracked Graphite plates.
C
On 6/5/2017 10:24 AM, 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.
>
> 73
> Gary K4FMX
>
>> -----Original Message-----
>> From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Clark
>> Turner
>> Sent: Monday, June 05, 2017 10:21 AM
>> To: amps@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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>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
>
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