[Amps] 3-500 / 4-400 cooling.

[R.Measures]

On Oct 9, 2005, at 8:13 AM, Chris Pedder wrote:

> At 14:40 09/10/2005, R.Measures wrote:
>
>> 3-500Z air system sockets and chimneys do not provide adequate cooling
>> unless a high pressure centrifugal blower is used.
>
> Perhaps that's because air system sockets were designed to be used
> with centrifugal
> blowers?

Not just any centrifugal blower, one that is designed to produce 
high-pressure.  Kooltronics makes such machines.
>
>> Such blowers are
>> quite noisy and I know of no Ham type amplifier that uses such.   In 
>> my
>> experiences, the transverse-air, >150mm slow-speed fan cooling system
>> used on the Heath SB-220 and Kenwood TL-922 result in lower
>> glass-envelope and filament-pin temperatures than those temperatures 
>> in
>> similar amplifiers that use air system sockets
>
>
> But the fact remains that both the SB220 and TL-922 suffer failures
> due to inadequate cooling of the filament pins.

Only when the 220's fan is not oiled, or where a 922 is operated from 
50Hz and used for RTTY broadcasting.   The fix for the 922 is to 
retrofit a Pabst (from Mouser) 172mm 12Vdc brushless fan and run it 
from the fil winding with a FWB and a C-filter.
>
>
>> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
>
> Perhaps the moral of this story is 'do what the manufacturer suggests'?

Are you okay with the Eimac using horizontal cooling fins in a vertical 
airflow?
>
> Chris G3VBL
>
>
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>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org