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RE: Alternatives to fiberglass boom

At 12:49 07/02/2002 -0500, you wrote:
>Wayne -- a quick way to test any material is to put a small piece in your
>Microwave Oven (running at full power). Heat it for 10-15 seconds. If no
>spark/flames are noted and the piece is not incredibly hot, then run the
>microwave for 60 seconds. If the piece is still at room temperature, it has
>excellent microwave properties. If it is starting to get warm, it's probably
>OK, If you can't pick it up, or if flames have been noted, forget it !!!
>If it made it OK to 1 minute, then you might want to give it a try at 2-3
>minutes just to make sure that the initial "good" diagnosis holds.

As a domestic electronics engineer, I am somewhat alarmed at this reply. If the material is good at 2Ghz, then you are running your 1Kw microwave transmitter ( your microwave oven ) into a VERY high SWR, certainly running it for 1 minute could irreparably damage the magnetron. It is VITAL that any tests of this type are conducted with at least a beaker containing 250ml or so of water accompanying the piece of dielectric to be tested.

Incidentally, if you take 1 litre of water, measure its temperature, heat at full power for 87 seconds, measure the temp again, then multiply the temp difference by 50, this will give a close figure to the number of watts generated by your microwave. My quick way of seeing if a microwave is working at rated power. 

Running your microwave without a load is like running your HF rig into an open circuit!, and microwaves don't have SWR protection!


     G4DMF  QTHR   IO93ha
     Amsat-UK Member 5372

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