Topband: KLIX, BUZZ, SPURS ETC.

[Mr. and Mrs. Magoo]

Both W4ZV and KD9SV have identified the cause of some of the garbage we are 
hearing on the band: RX-only antennas which are not disconnected during 
transmit.  Most current transceivers employ a PCB-mount relay to switch the 
main and AUX antennas, and these do not offer very much isolation between 
antenna jacks.  Furthermore, in some radios the unused jack is not grounded, 
leading to the problems we are hearing.

I had this problem occur myself  a few years ago with a transceiver and two 
different linears.  In both cases, the linear started pulling very heavy 
current,  as if it was going into oscillation.  It did this only when one of 
my Beverages, passing within about 75 feet of the TX antenna ,was connected 
to the RX antenna port. I had established a nice feedback loop, with energy 
from the TX vertical being coupled through the RX antenna and back into my 
transceiver.

I installed what KD9SV calls a "front end saver", the design for which 
appeared in his CQ Magazine article, February, 1997.  My version is a bit 
different, as it removes power to the remote relay switching system for my 
Beverages, and this grounds everything, including the RX port on my 
transceiver.  For those not having an idiot-proof linear amplifier, this 
system is also a "linear saver"!

I strongly urge those not using such a system to install one.  If you are 
not a builder then Gary's excellent design is available commercially ready 
to plug 'n play.

Let's clear up the garbage on the band-if you use an external RX-only 
antenna, install some means of disconnecting it and grounding the port 
during TX.

Bill, VE3CSK