[Amps] Should a blower run after amp shutdown?

[Jim Thomson]

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From: "Jim Tonne" <Tonne at Comcast.Net>
Sent: Friday, June 03, 2011 6:47 AM
To: "Jim Thomson" <jim.thom at telus.net>; <amps at contesting.com>
Subject: Re: [Amps] Should a blower run after amp shutdown?

>
> Gents:
>
> I asked a former co-worker (WA5LFY) how our "big" rigs were shut down;
> he was still working on them after I left the company.   Here is his 
> reply:
>
>>  The screen voltage needs to come down first, with the drive at the same 
>> time.
>>  Then the high voltage comes down.  That prevents high screen current 
>> which would
>>  occur if the high voltage is removed first, leaving the screen to look 
>> like an "anode".
>>  With drive, screen, and HV removed, the bias supply can be removed, and 
>> filament
>>  ramp-down can occur.

####  Notice how he  ramps  down the fil V....when done for the night .  I'm 
100%
convinced that ramping down the fil V is  less stressful on big fil's.  It 
would
certainly reduce thermal stress and shock.  Emtron does the ramp up 
sequence...dunno
if they do the ramp down part of it though.   Does anybody know ?

Jim  VE7RF



  After all of that, the cooling can be removed after
>> a brief
>>  cool-down period (I used about 3 minutes to remove any residual heat). 
>> All
>>  together, it takes about 10 to 15 minutes on the 500kW.
>
> I think that response would be of interest to the group.
>
> - Jim W4ENE
>
>
>
>