Towertalk
[Top] [All Lists]

## Hot Antennas

 To: Hot Antennas rhummel@monad.net (Rob Hummel) Wed, 3 Jul 1996 09:05:28 -0400 (EDT)
 ```>Well, I have some problems with the premise that the KT34XA traps have that >much internal resistance that there is significant heating under rf load... It's really not that hard to understand. Let's boil down the math for a simple loss budget for a connection made with a ham-type UHF connector. Loss per connector = 0.05 dB (doesn't seem like much, eh?) Total loss = 0.10 dB (who even counts this stuff, right?) 1500 W * 0.10 dB = 1500 W * (1 - 10 ^ (.01)) = 1500 W * .0233 = 35 Watts! That's right. For every connector pair, you lose 35 watts. A 0.3 dB loss in a switch subtracts 107 watts from your ability to break a pile-up. And for every 1 dB of loss in your feedline you squander 388 watts. (So much for the guys who say, "Oh, RG-8 is essentially lossless at HF.") Assuming that the connections to a typical trap combined with ohmic resistance has the same miniscule 0.1 dB loss as a connector pair, it's essentially a 35W heating element. No need to climb the tower. Just turn a 35W bulb on for a while, then grab it tight to simulate this experience in the comfort of your living room! For a safer thrill, add up a loss budget for your station and see how little of your power is actually reaching those expensive antennas. Rob Hummel (WS1A) ```
 Current Thread Hot Antennas, Rob Hummel <= Hot Antennas, Bill Turner Hot Antennas, Del & Jan Seay Hot Antennas, Rob Hummel