[Elecraft] Need coax relay to switch ant between K2 & K3

[Don Wilhelm]

Alan,

I would suggest something a bit more complex than a simple SPDT relay to 
switch between the K2 and K3.
Considering that the antenna should be disconnected when not in use, I 
would devise a priority scheme - it would take 3 relays.  Two would 
switch RF between the antenna and a dummy load.  The third would switch 
the DC feed to the two RF relays depending on which transceiver has 
priority (the K2 or the K3) and the power on state of the K2 or the K3.

Yes, that would take 2 dummy loads, but provides a safe load if the 
antenna is not selected for either the K2 or the K3.  The priority is 
your choice - if you want the K3 to be the priority transceiver, its 
power on state will prevent the K2 antenna relay from activating (or 
vice-versa).
 
Tha downside is that if you forget to turn off the K3, you will have to 
make a trip to the K3 to turn it off before you can use the K2.  The 
up-side is that you will always have a safe load to boht the K2 and the 
K3 and if you power off the rig when not in use, you will have some 
protection from lightning surges on both rigs.  Instead of "disconnect 
the antenna when not in use", you will have implemented a "power off 
when not in use" mechanism that will automatically disconnect the 
antenna and connect the rig to a dummy load.

I am working on a similar situation, but I am using mechanical rotary 
switches in the hamshack.  Of the 3 HF antenna feeds and 1 6 meter feed 
coming into the shack, any unused antenna feeds will be routed to the 
basement workshop.  In the hamshack, the K3 has the priority choice of 
antenna feeds, the Yasesu FT-847 has the second choice and the remaining 
coax feed is sent to the workbench.  The K3 and FT-847 are protected by 
dummy loads when powered off, but the workbench feed is manual - i.e. at 
the workbench I must physically disconnect the antenna from any rig on 
the bench when not in use.  Mine is more complex because the 6 meter 
must connect to the HF antenna jack on the K3 while the 6 meter feed on 
the FT-847 is separate from the HF input.

You will have to come up with your own system based on your particular 
desires and priorities.  A bit of thought and "midnight sketches" may be 
in order.

73,
Don W3FPR

Alan D. Wilcox wrote:
> Hello,
>
> The saga of my K2 in the upstairs office and the K3 downstairs in the 
> shop continues.
>
> Solution:
> 1. Run coax from the K2 into the attic; run some red/blk zip cord up too.
> 2. Chop the K3 coax going to the antenna and run the K3 end into the attic.
> 3. Run the remaining end of the coax from the antenna into the attic.
> 4. PL-259s to the 3 wires in the attic.
> 5. Connect K2, K3, ant to coax relay.
> 6. Zip cord to relay (12 vdc or 110 ac); other end gets power when I 
> turn on the K2 supply.
>
> I had a Dow-Key coax relay (just what I want) on my Viking II. Both long 
> gone.
>
> Anyone have one or something that'll do the trick? Any extra PL-259's 
> with sleeve for smaller coax?
>
> Many thanks!
> Alan
>
> Alan D. Wilcox, W3DVX (K2-5373, K3-40)
> 570-321-1516
> http://WilcoxEngineering.com	
> Williamsport, PA 17701 
>
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