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Mike Coslo · July 31st 06, 11:46 PM posted to rec.radio.amateur.antenna

wrote:
Yes, I did think of temperature concerns. The radio unit itself should
be kept at above freezing if my calculations are correct. However,
does the antenna need to be kept warm?

Hi Brett

In most cases, the transmitter will be in an enclosure. I'm assuming
that there will be an experiment package. Many who do this sort of thing
will make the enclosure out of Styrofoam. Some actually use styro picnic
coolers. For typical flight durations, the inefficiencies of the
electronics equipment on board the payload (read waste heat) will make
up for the nasty temps outside. I've seen some cases where there has
actually been a temperature rise. The criteria is a well sealed
insulating box.

And no, the antenna itself does not need to be warm. Just seal off the
exit port to keep internal heat from leaking out.

Your watt should be sufficient power. At 100 kilofeet, you will reach
more that you likely want to reach! I've seen propagation maps that show
a single balloon repeater at these heights covering 1/3rd of the US.

- 73 de Mike KB3EIA -