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[AMPS] Cantenna Dummy loads

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Subject: [AMPS] Cantenna Dummy loads
From: (Gilmer, Mike)
Date: Wed, 3 Feb 1999 15:08:10 -0500

I'm not sure if I understand the first sentence entirely, but it seems
to indicate that you are counting on the presence of the water coils as
being sufficient to cause or improve oil circulation.  I don't think the
coils will help in this regard.  Of course there will be some
circulation just because of the heating of the resistor.  I just don't
believe that this natural circulation is enough that the oil can draw
away large amounts of heat.  That's why I suggested the test.  If the
oil at the outer edges (along the can surface) is not warmed up in the
10-20 seconds that it takes to "detune" the resistor, then additional
oil at or near this surface (or cooling coils) will have no heat to
remove, therefore will be useless.

Remember the GOAL:
One is not trying to get the heat out of the oil, per se.  One needs to
transfer the heat out of the RESISTOR.  If the oil isn't doing the job
(lots of local heating, boiling, burning, bubbling, VSWR changes) then
the first order of business is to improve THAT transfer.

On the other hand, if you were heating the Cantenna with, say, 100 or
200 Watts, then the local heating of the resistor would probably not be
the problem.  The problem would be in getting the heat out of the oil.
A big can or cooling coils WOULD help.

Mike N2MG

> -----Original Message-----
> From: William L. Fuqua III []
> Sent: Wednesday, February 03, 1999 2:13 PM
> To:   Gilmer, Mike
> Subject:      RE: [AMPS] Cantenna Dummy loads
> The water cooling coils have the advantage that 
> convection currents of oil should be formed as
> the warmer oil rises around the resistor and
> flows downward at the outer region of the can to 
> the cooling coils. 
>   Oh by the way, I do have a 5KW water cooled dummy
> load but have not used it yet. It just seems to me
> that a Cantenna with optional water cooling would
> be very useful because of most test you would not
> have to have a water supply. You would just have to
> have it for the times you are testing with long key
> down intervals.
> 73
> Bill wa4lav

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