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" <w2xj@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
>
>
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_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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