Several companies (Bird, Transco) make what you describe. It is a four terminal coax relay called a "Transfer Switch" that for example, connects any two antennas to any two radios, but never at the same time. In other words, radio A connects to antenna 1, and at the same time, radio B connects to antenna 2. Activating the switch ( either mechanical or electrically activated) changes the condition for A to 2 and B to 1. Most are good for a kilowatt well up into the UHF ranges. For HF, I made one using a heavy DPDT relay.
73 Charlie k3ICH -----Original Message----- From: Elecraft [mailto:[email protected]] On Behalf Of Richard Fjeld Sent: Monday, January 02, 2017 1:13 AM To: [email protected] Subject: 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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
