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Re: LF: 500 kHz - Fans

from [Graham] [Permanent Link][Original]
To: <[email protected]>
Subject: Re: LF: 500 kHz - Fans
From: "Graham" <[email protected]>
Date: Sat, 20 Jun 2009 13:38:05 +0100
Importance: Normal
In-reply-to: <[email protected]>
References: <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
Chris.....
 
Oh dear ....hi .... Well I would think that the fan coils my  be  acting as antennas and  subjecting the electronics control board to 'slight' over voltage ... can you  pick up a ex equipment  'ac' fan , I have a System Papst TYP -8550-N  230V/50hz , which moves quite a bit of  air , about 3 inch mount , that would solve the  problem ?
 
G ..

Sent: Saturday, June 20, 2009 7:34 AM
Subject: LF: 500 kHz - Fans

LF,
I've nearly completed my new PA for 500 kHz and have now managed to
stop destroying FET's.
 
Unfortunately I have an unusual problem in that the heatsink cooling fans
are going U/S.
 
I have used 24 volts brushless PC-type fans and after a while they
either die completely or start to go backwards slowly. . .
 
The fans may be slightly over-run but only by a volt or so and on key-up
(unregulated supply) and are situated about 50 mm (2 inches) from the heatsink.
I have rf decoupled them from the supply but maybe not well enough !
 
Any suggestions in curing this problem would be most welcome.
 
73 Chris G3XIZ
 
 
 


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