[Elecraft] Antenna switching [K3]

[Don Wilhelm]

Mike,

Relays are the answer IMHO.
Take a look at the "A Low-Cost Remote Antenna Switch" by Bill Smith 
KO4NR in QST April 2005.
ARRL measured the isolation at >60 dB except for the two innermost ports 
which were 50 dB at 28 MHz.

FAR circuits has boards for this project.

I built 3 for switching my many HF antennas down to 3 runs of coax into 
the shack (not all the ports are used, I have only 12 HF antennas to switch.

As for preventing transmit out of one K3 antenna port into your Aux Rx 
port, rotary control switches will likely help since a simple rotary 
switch will only activate one relay of any set.   If you have more than 
one set of remote relays and you connect any one antenna to 2 or more of 
the remote switches, then you could transmit back into the receiver, so 
connect any one antenna to only one relay port and make all the other 
arrangements with switches to the relay coils.

Yes, when I get around to completing the complete system, the KRC2 will 
control the selection from the K3 automatically - the ACC outputs select 
between 3 sets of antennas.

73,
Don W3FPR

Mike Scott wrote:
> I put up a vertical yesterday to begin playing with diversity mode.
>
> When I installed the sub receiver I opted to connect the Aux RF BNC
> connector. Now I am not sure I made the right decision for me as I want to
> be able to easily switch transmit and receive antennas. Of course then my
> 20M dipole and my 6 M vertical would be just sitting there unconnected and
> to switch bands I have to plug new cables in. I have more antennas planned
> for the future and I may try some kind of low noise receive-only antenna.
>
> In the old days a simple antenna switch would be all I need but now I have
> multiple simultaneous antennas to switch and I need to make sure I don't
> transmit out of Antenna 1 into the Aux Rx port ;-)
>
> So now I am considering building some kind of well isolated Antenna switch
> matrix. I am interested in what others are doing. If I use relays, how does
> one build for good cross-talk isolation between antennas? Maybe all I need
> is two or three simple antenna switches.
>
> Mike Scott - AE6WA
> Tarzana, CA (DM04 / near LA)
> K3-100 #508/ KX1  #1311
>
>
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