If its RF that is a concern the only positive method would be feeding it into a 50/75 Ohm resistor when transmitting.
I had to do that some years ago when a Beverage ran between the phased vertical pair and after cooking a few parts in a TS-940. Beverages are now well away from any TX antennas. Carl KM1H ----- Original Message ----- From: "W2XJ" <w...@nyc.rr.com> To: <topband@contesting.com> Sent: Sunday, June 17, 2012 11:03 AM Subject: Re: Topband: Detuning transmit antenna in receive > There is no single solution for detuning an antenna it depends on > electrical length. For verticals a quarter wavelength or less it is > common to have a contactor between the network and the radiating element > and open the connection to float that element. This is the practice in > commercial directional arrays where some tower are not used in a day or > night mode. This does not work well on taller towers and I do not know > offhand how it would work with the T. It is easy enough to model in EZNEC. > > On 6/16/12 3:02 PM, Shoppa, Tim wrote: >> OK, several folks came back and recommended detuning my transmit antenna >> in receive. >> >> Certainly any receive antenna I have is going to be in the shadow of my >> transmit antenna, a 130-foot flat-top about 85 feet up, fed against >> ground. (Really it's an 80 meter doublet fed with ladder line. I tie the >> ladder line together at the bottom and feed against ground.) >> >> Trying to figure out what "detune" is. >> >> I match the transmit antenna to 50 ohm coax with a L network at the >> bottom. If I want to detune, then I can.... open up the connection >> between the antenna and the L network at the bottom? Unhook the L or C in >> the L network? Short out the antenna where it comes into the L network? I >> could rig up a relay contact to do any of those. >> >> Tim N3QE >> _______________________________________________ >> UR RST IS ... ... ..9 QSB QSB - hw? BK >> > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1424 / Virus Database: 2433/5075 - Release Date: 06/17/12 > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK