Topband: Detuning Xmit Antenna while RXing.

Ulrich Weiss dj2ya at
Sun Jul 27 21:13:07 EDT 2003

hi Ernie,

Earl's answer and your last mail show that you have solved the switching
problem, but just let me draw your intention to a possible
misunderstanding... in your mail below you ask for a way to "unground" your
vertical on transmit and "ground" it on receive...
if your vertical is of the quarter-wave species you should do just the
opposite... the optimal detuning of a quarter-wave vertical is to "unground"
it (and disconnect the feedline) and move the radiator's resonant frequency
to its halve-wave frequency...
of course, if your vertical is a half-wave device (unlike on 160m) you must
"ground" it for detuning...

Uli, DJ2YA

----- Original Message ----- 
From: "Ernie" <ks4q at>
To: <topband at>
Sent: Sunday, July 27, 2003 3:37 AM
Subject: Topband: Detuning Xmit Antenna while RXing.

> I'm running an FT-1000MP here and am experimenting with various receive
> antennae.
> Can anyone point me to a circuit that I can construct to drive a vacuum
> relay to unground my Xmit antennas on Xmit....or ground my Xmit antennas
> Receive as it may be.
> Very obviously, I'm trying to keep the Xmit antennas from interacting and
> disturbing the patterns of my RX antennas.  I plan to do this for both 160
> and 80 meters....separate vacuum relays with steering diodes.
> Thanks, Ernie KS4Q
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