[Elecraft] Dual Receivers 2 different antennas Diversity receive

[Don Wilhelm]

Such a relay is a workable solution.
BUT be aware that the K3 KEYOUT only provides a ground.  The relay coil 
must be connected to a voltage source.  Since you are also using an 
amplifier on the KEYOUT line, you will have to carefully match the 
voltage of the relay and its voltage supply with the voltage provided in 
the amplifier - if you do not, there will be current flow between the 
amplifier and your relay's power source.

That current flow can be prevented by the use of a series diode in each 
leg of the "Y".  If the diodes are used, there is not as great a need 
for matching the voltages.

So things are a bit more involved than just using a "Y" cable.

73,
Don W3FPR

On 1/28/2020 5:31 PM, Conrad PA5Y wrote:
> If you want to be absolutely certain you could add an external relay driven from the key output. If you use this port to key you PA then you can just use a Y splitter. There are hundreds of suitable relays on eBay. Configure so that on TX the sub RX is terminated with 50 ohms. Typically relays such as Dow Key 401 series will give well over 100dB isolation on HF through 6m, they say 85dB but it's a lot more on all the ones I have measured.
> 
> For example
> 
> https://www.ebay.com/itm/Dow-Key-401-175-RF-Microwave-Switch-15V-SMA-NSN-5985-01-320-1388/143186092545
> 
> Regards
> 
> Conrad PA5Y
> 
> 
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On Behalf Of VernonJ
> Sent: 28 January 2020 20:28
> To: elecraft at mailman.qth.net
> Subject: [Elecraft] Dual Receivers 2 different antennas Diversity receive
> 
> My K3S has Main and Sub receivers. I would like to use Diversity receive with the Main using the transmit antenna, and my Sub using a small receive loop.
> Is there sufficient isolation on the Receive Only antenna connection to protect the Sub? Antennas are 60 feet apart, and I intend to run 500 watts at some point. If I need additional isolation and protection, how would I do this? Thanks.
> 
> 
> 
> --
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