Fred: The KPA500 doesn't have antenna selection, automatic or otherwise. It has one input SO-239 connector for the transceiver and one SO-239 connector for the amplifier output.
One way to approach this, used by many, is to use the K3 band change lines on its accessory connector to control an external antenna switch. Band decoders are available with varying degrees of capability (and cost) from Elecraft (KRC2), Unified Microsystems (BCD-10) , Top Ten Devices (BD-Y-SD) , microHAM (Station Master and an earlier Band Decoder) , Array Solutions (several, their current is called the BandMaster III), and others. The Unified Microsystems BCD-10, perhaps augmented with its HSD-9 High Side Driver Board, is among the most affordable of these. Each of the choices has some characteristic that makes it an attractive solution if it fits your overall station. Some have manual override. Some provide visual indicators to show the selected antenna. It's also possible to roll your own, it can be a simple one IC project for the decoder chip plus whatever transistors you need to drive your chosen relays. The K3's band change lines go from its back panel accessory connector to the band decoder. The decoder controls an antenna switch (a number of relays) that switches one RF input line to any of N antennas. The list of antenna switch manufacturers is long and includes microHAM, Top Ten Devices, and Array Solutions. Some multiple-radio stations use a pair of band decoders, one per transceiver, and a 2 x N antenna switch that allows either radio to use any antenna, and keeps both radios from selecting the same antenna. I use an Array Solutions "SixPak" for this. There are other newer products. The Antenna1 output of the K3 goes to the KPA500 transceiver in. The KPA500 output goes to the antenna switch common. The antennas connect to the antenna switch. If you're building a multi-radio station with antennas anywhere near one another, you'd want to add some band pass filters, also automatically switched, between the K3s and their amplifier(s), to protect the receivers from the other transmitter(s). And we call this hobby "wireless"... Some amplifiers have a couple of antenna outputs. Ours doesn't. Whatever number of antenna connectors we chose, other than one, would be too few for some and too many for many. 73 de Dick, K6KR -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Fred Maas Sent: Sunday, July 10, 2011 6:36 AM To: [email protected] Subject: [Elecraft] KPA-500 Question something I don't see in the specs of the KPA500, and I wonder if possible .... the ability to have the KPA500 remember which antenna to associate with which band, and appropriately switch a remote electronic antenna relay. Automatic amplifier band switching is of limited usefulness unless the appropriate antenna is selected automatically at the same time. Possible or not? TNX, 73, Fred - kt5x K2 # 0700 K3 # 0144 aka W5YA / qrp aka WS0TA / SOTA ______________________________________________________________ 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 ______________________________________________________________ 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
