[Elecraft] R: {OT} - Variation on use of a coaxial switch (stan levandowski)

[glcazzola at alice.it]

Sorry, but why not buy a used Bird Coaxwitch with his isolation higher than 80 dB?I use them and like them very much.
Ian IK4EWX

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  Messaggio originale  
Da: Richard Fjeld
Inviato: lunedì 2 gennaio 2017 07:13
A: elecraft at mailman.qth.net
Oggetto: Re: [Elecraft] {OT} - Variation on use of a coaxial switch (stan levandowski)

Years ago, I built such a switch to prevent accidents should one radio 
transmit when comparing two radios. It is basically an a/b switch such 
that a radio became the active radio by switching the antenna to it, and 
simultaneously switching the dummy load to the inactive radio. Neither 
radio is without a load regardless of the switch position.

My switch is just a prototype using an aluminum project box. I called 
MFJ and suggested they build one. A couple guys got on the call with me, 
and not long afterward, I saw a product advertised that seemed to be 
it. It had decent specs for isolation. I can't find it on their site 
now. The only thing that comes close to it might be the MFJ-1705, but 
they are describing it differently and there is no schematic.

If this isn't the correct switch, It could easily be converted. The 
important hardware is there. I think I used a DPDT switch (I could 
check mine).
It should have the small coax wired between the connections. I Don't 
remember the nomenclature for that.

Dick, n0ce


On 1/1/2017 5:18 PM, Harry Yingst via Elecraft wrote:
> I've also have thought about running a switch so I can switch between a couple of radios here (and a way to idiot proof it).
>
> I have considered building up something using relays (or a manual switch) that would switch each radio into either a dummy load or into the antenna path.
>
>
>
>
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