Take a look at MFJ-1707, or HB your own. I built one years ago, but never got around to building the receive antennas, so didn't really try it out.
Jim K0XU On 6/9/2010 6:31 PM, Dick Dievendorff wrote: > John: > > You don't have a lot of time before this Field Day, but in the longer term, > there's a better way. > > For this Field Day, I'd look for a manual switch from MFJ or Alpha-Delta or > something along those lines. > > The K3 (and most other radios of recent vintage) provide back-panel "band > change" or "band level" lines that can be used for this purpose. The K3 > uses a 4-line (plus ground) BCD encoding on the back-panel accessory > connector to indicate the band. Yaesu uses the same scheme. Band decoders > for this 4-line BCD encoding that are advertised for Yaesu products work > well with the K3. > > ICOM uses a different scheme, but the idea is the same. > > Available band decoders for the K3 / Yaesu 4-wire BCD protocol include: > > Elecraft KRC2 http://www.elecraft.com/KRC2/krc2.htm, > > Unified Microsystems BCD-10 http://www.unifiedmicro.com/decoder.html See > the link at the bottom for a more complete description of a simple switching > system. http://www.unifiedmicro.com/BBCD10_BLK.pdf > > Top Ten Devices http://www.qth.com/topten/bdecoder.htm > > Array Solutions > http://www.arraysolutions.com/Products/bandmaster.htm#top%20of%20page > > and microHAM http://www.microham-usa.com/Products/band%20decoder.html > > The capabilities (and prices) of these devices varies considerably. Some of > them have many more functions than just band decoding. > > These all help to automate the antenna selection process. You change the > frequency from the radio front panel (or your logging program on your > computer), the radio provides signals to the band decoder, the band decoder > provides +12V to an appropriate set of relays, and the relays select the > appropriate antenna. Some antenna relay boxes can switch two radios to N > antennas, and isolation becomes a very important issue. > > There are antenna relay boxes available from some of the same sources. I've > seen any number of construction articles in QST and NCJ about this. It's a > popular station automation topic for contesting stations. In a contest, > particularly with guest operators, it's ideal if you can just change the > radio's frequency and start transmitting, everything else is automated. Some > of my current antennas require an ATU, and I have to tune my amplifier, but > I'm hoping someday to automate all that, too. The really competitive > stations have all this automated. > > You could ask this question on the TowerTalk or CQ-Contes reflector and get > lots of advice... > > 73 de Dick, K6KR > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of John Watkins > Sent: Wednesday, June 09, 2010 3:33 PM > To: Elecraft Reflector > Subject: [Elecraft] K3 with xmit and receive antennas - advice needed > > All, > > My K3 does not have the option that provides for the third antenna input > (KXV3). Would the following method allow me use dual antennas for Field > Day. Use the switched 12 volt out to drive an antenna relay to make the > changeover. > > Will this work? Is there a better approach? > > Thanks, John N0EVH > ______________________________________________________________ > 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 > > ______________________________________________________________ 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
