http://elecraft.85.s1.nabble.com/Transmitting-while-listening-in-diversity-mode-tp5897822p5898956.html
> Tony Estep wrote:
>> Nobody commented on my question last night, but I'd still like to hear from
>> your collective wisdom, so here's a repeat: I set up my sub-rx to listen on
>> transmit antenna B while the main is listening and transmitting on A, and to
>> listen on A while main is listening and transmitting on B. This allows for
>> diversity reception.
>>
>> "...here's my question: My two antennas are located so each is in the
>> other's null, but they are not far apart, maybe 50 feet at most. When I
>> transmit, I don't hear any carrier-operated relays or see any adverse
>> reactions, but I'm still not sure that it's okay. The manual sez "well
>> isolated," but what I'm looking for is some objective way to test or
>> measure. Can anyone tell me how I can establish for sure that I can, or
>> cannot, transmit on A when the sub is connected to B, and vice versa? "
>>
>> Any info (especially first-hand knowledge) would be much appreciated.
> Connect a simple diode milliwattmeter to the feed from the RX antenna.
> All it needs is a 47 ohm resistor, a 1N914/4148 diode, a .01uF ceramic
> cap and your DVM. (This is truly a "Construction 101" project - can
> anyone supply a suitable web reference, please?)
>
> Gently ramp up the power to the TX antenna, and see how much power is
> coming back on the RX input. Repeat with every combination of bands and
> antennas.
>
> Also read "Managing Interstation Interference" by George Cutsogeorge
> W2VJN:
> <
http://www.inrad.net/product.php?productid=248&cat=148&page=1>
>
> The first chapter is available as a free download and contains key
> information about power levels for receiver front-end damage. The K3 can
> protect itself... but as you say, you should make sure it doesn't have
> to.
>
> For diversity I am using an active antenna based on a small horizontal
> dipole, which works very well in combination with the low-band
> verticals. Checking with the milliwattmeter and gradually ramping up to
> full TX power, both the active antenna and the K3 are well enough
> protected by the cross-polarization. But the 20-10m beam is horizontal
> and also much closer, so additional protection is needed on those bands.
>
>
>