Here's a thought. I was faced with the problem of having a fairly large selection of HF antennas, and 3 operating stations. What to do? After some thought, I decided to create a matrix-type switch that could control 10 different antennas into any of 5 rigs, in any combination. That equates to 50 different setups, not counting multiple feeds.
The controller also allows multiples, in that any antenna can be connected to more than one rig, and any rig can be connected to more than one antenna. This is occasionally useful for special receiving situations or experimentation. The controller features a locking function that works with my station controller (the gadget that manages which rig is allowed to be "on air" and which audio or keying source is delivered where, as well as audio outputs from the associated receivers). The lockout function makes it impossible to transmit into another rig, or cause any other similar problem. If I could have my 'druthers, I would have integrated the lockout function directly with the rigs themselves, but when it was being built, very few rigs (if any) were available that could do this. Modern rigs, such as the K3 could accommodate this, I think. I do have to be careful and not key up a rig "internally" (using it's own transmit function button). But there is a BIG red light that comes on to help remind me. Only did that once, years ago, with a Kenwood TS-940S, but that rig's input overload protector handled the fault with no other apparent damage. My version does have a small amount of cross-talk (about -50 dB) that a somewhat better design could reduce further. Overall, the project was extremely successful, and works better than I could have envisioned. It uses a control-head + switch unit architecture (the actual matrix switch is mounted away from the operating position). It was NOT cheap, but 20 years later is still performing flawlessly, so the cost per year continues to decline. I was able to recoup some of the expense by selling a hat-full of other coax switches - which by the way would drive me crazy to operate as there never seemed to be the right combination for all the different setups I wanted to use. I did NOT attempt to create something that would perform at VHF and above. My switch is strictly a HF/MF device. The insertion loss is on the order of 0.5 dB or less, depending on band. Measured VSWR, last time I looked, tends to stay below 1.25:1 on any frequency or equipment combination, except of course for multiple connections. Not perfect, but good enough. An antenna coupler makes what minor corrections are needed, if I were to care about such things, which usually I don't. Getting that last little bit of SWR out is not worth the trouble, usually, particularly at HF. VHF and above is different. Handles 1500 watts with ease. - Jim, KL7CC . Eric Swartz - WA6HHQ, Elecraft wrote: > I'd like to redirect this discussion to what is be desired for an > external antenna / rig switching add-on box for the K3/KPA500 and/or > KAT500. > ______________________________________________________________ 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
