On Tue, 17 Aug 2004 14:01:06 -0700, Roy Lewallen
wrote:

The method you propose seems workable, except I didn't see any mention
of heat leaving the box via thermal conduction along the wires.
Depending on the box's insulating property and the wires, this could be
a significant contributor to the total heat loss from the box. Therefore
it's very important to either insure that this loss is negligible
compared to the loss through the styrofoam, or else to manage it (most
easily by using exactly the same wires and wire orientation during
calibration and test).

In my original post I suggested using the same container and the same
cable to feed either the antenna or the dummy load. Thus the power
escaping through the feedline is the same in both cases and thus,
cancels out.

My suggestion of using a cold liquid and measuring how long it takes
until it gets warmer just helps to give a ballpark value of the
thermal conductivity, which will help to set the appropriate power
levels for the actual antenna/dymmy load tests, i.e. not too cold or
too warm.

Paul OH3LWR