-----Original Message-----
From: wb4mnf <wb4mnf@atl.org>
To: Douglas R Snowden <Douglas.R.Snowden@noaa.gov>
Cc: amps@contesting.com <amps@contesting.com>
To: <amps@contesting.com>
Date: 24 March 2002 15:06
Subject: Re: [Amps] Amps that are GI7B candidates ?
>I'm having trouble with the cooling requirements of this tube.
>Specs say 350 W requires 40 m**3 per hour. At 1.2 kg.m**3, that's
>52 kg/hour air, squeezed through a 200mm**2 heat exchanger 'duct'.
>
>If air were not compressible, this would translate to a 200km/hr
>air stream! I did calculate the temp rise and IIRC(notes at work)
>the exiting air will be 24 degrees C warmer than the entering air
>for this mass flow and transfer of 350W.
I wonder if you've slipped a decimal place somewhere? I reckon that 40 cubic
m/hr is about 24cfm, which seems very reasonable. For comparison, a 120mm
axial fan moves 80-100 cfm in free air. I'm not familiar with using GI7b in
practice, but it looks as if you could blow air onto the end face of the
anode and let it exhaust radially, in which case the pressure drop will be
quite low and an axial fan should be plenty. The downside is possible
heating of anode components in the area but even something that enclosed the
airflow in the opposite direction should not introduce a huge back pressure.
A couple of sites I looked at stressed the need to cool the cathode every
bit as much as the anode.
Steve
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