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Old June 3rd 07, 12:25 PM posted to rec.radio.amateur.antenna
Mike Kaliski Mike Kaliski is offline
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First recorded activity by RadioBanter: May 2007
Posts: 182
Default Through-glass antenna power limits


"Thomas & Karen Mitchell" kg7uATolympus.net wrote in message
...
(I realize that a through-the-glass antenna is less than ideal.
Nevertheless, that's what I have to use in my situation.) The one I
have is for 2 meters (NOT dual band), and the label says up to 50
watts. I have an Icom IC-2200H, which has a maximum of 65 watts
output.

What bad things may/could/will happen if I put 65 watts through the
antenna?

Thanks!

Tom Mitchell -- KG7U
Port Angeles, Washington. USA
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Tom Mitchell, Port Angeles, Washington, USA
http://www.olympus.net/personal/kg7u
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Tom

Through glass antennas work using capacitance. The two plates either side of
the glass form the capacitance with the glass acting as the insulator.
Attempting to put too much power through a capacitor usually results in
overheating or a breakdown of the insulator. This could potentially result
in a broken screen.

Another thing to consider is the mismatch that the through glass capacitor
makes with your transmitter. Some of the power will inevitably be reflected
back to the output stages causing possible overheating at full power.

I would guess that 65 watts would be safe enough for brief transmissions but
for longer chats keep the power down below 50 watts. For mobile use, the
difference in signal strength, a fraction of an S-point, is unlikely to be
noticed by anyone receiving your signal.

Mike G0ULI