Here's a link to the ELT antenna picture (the exact antenna I am using
across the com band). You can get as abusive and abrasive and you want.
Tell me theory all day long and it still doesn't matter. The fact is,
it WORKS in my installation and has been for about 7 years now.

http://www.chiefaircraft.com/Aircraf..._05-02-006.gif

Tell me more about the LC trap on this antenna.

Scott Littfin



RST Engineering wrote:

First, send me the model of the instrument that you used for the
measurement. Then explain why the trap in the antenna didn't totally mess
up the VSWR for the VHF band. You DO understand that an ELT antenna is a
trap monopole, don't you? You DO understand that the top 2/3 of the antenna
is decoupled from the bottom end by an LC trap, don't you? That a properly
operating ELT antenna should be 2:1 or less at 121.5 MHz. and more than 10:1
above 123 and below 119 MHz?

My bet is that you used a CB power meter, good buddy, 10-4.

Of course, you could be measuring a 51 ohm resistor that somebody put in the
antenna to "match" the antenna across the band. That would let the antenna
radiate about as well as a limp piece of spaghetti in a copper septic tank.

Jim




"Scott" wrote in message
.. .

I can send you forward and reflected power readings if you wish, say every
1 MHz from 118 to 136. Now, with that said, that is measured on the
ground, not in flight where the whip curves back from all the high speed
flying at 75 MPH

Scott