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[AMPS] Blowers

To: <>
Subject: [AMPS] Blowers
From: (Dave Kirkby)
Date: Thu, 12 Mar 1998 20:16:57 +0000
I said Earlier:

> >While its probably true that if the pressure is okay, then the flow
> is
> >too *if you use the correct bases*, you can not apply this if you
> make
> >your own bases, which many amateurs do.  Neither can it be applied in
> >the case of some of the triodes (3CX5000A7, 3CPX5000A7, YC156,
> >3CX15000B7) and others, where you need to cut some slots in the
> chassis
> >for air flow.

R. L. Measures replied.

> It can if one measures the differential pressure drop across the anode
> cooler with a manometer.
> cheers
> Rich...
> R. L. Measures, 805-386-3734, AG6K

According to my reasoning, this is simply not true. The Eimac data given
is for the tube and socket used together. The pressure drop quoted in
the data sheet would be the sum of the pressure drops across the socket
and anode cooler - pressure drops add algebraically. You should not them
compare that to the pressure drop across only the anode cooler, which
will always be less (for the same flow) than the pressure drop quoted in
the data sheet.

Aiming to get the same pressure drop across only the anode cooler, to
what Eimac get across the socket/tube combination, would be a safe
practice, but it might mean you use a bigger blower than necessary.

If you make an assumption, for the sake of argument, that a tube has 5"
droped across the anode cooler, and 1" across the socket. The data sheet
would just say 6" (5+1=6). Now if you stick a manometer across only the
anode cooler, and adjust a fan speed for  6" of pressure, you would
infact be running at about (6/5)^2 = 1.2^2 = 1.44 x as much flow as
needed. I dont suggest these figures are representitive, but I think
they prove your theory does not hold.

Perhaps I'm wrong.  Perhaps I have misunderstood your argument .....


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