If you are working the bands 30m and below and have the room you can use inverted V antennas that all have the same feed point. The power will be distributed to the the antenna that is resonent at the transmit frequency.
Until I was able to get room and funds for rotable antennas and longer wire antennas I used inverted V antennas fed from the same point. On Wed, 08 Jan 2014 15:45:48 -0500, you wrote: >An OCF is an unbalanced antenna and it must have a choke to keep RF off >the feed line into the shack. I use about ten turns of coax on a 4 inch >PVC pipe right outside the wall where the feed comes into the house. It >might be more or less, I am not at home to look. You can research it. >Other choke baluns would help, if they present a high enough impedance. > >That seems to have cured RFI problems for me but I have occasionally >felt like I needed more isolation. Many people have advised me to get >rid of the OCF and go with something balanced but it suits my multi-band >needs for now. > >I am pretty sure RF on the feed line would cause the tuning circuits in >the KAT to act crazy. I'll leave that one for the Elecraft gurus to >answer. > >Buck >k4ia > >On 1/8/2014 5:57 AM, Ray Coles wrote: >> As the original poster under this heading I figured you might be interested >> to know what I have achieved so far, even though I am not yet ready to send >> the white smoke up the chimney. Briefly, my problem was that my KAT500 >> would go into uncommanded tunes during a QSO, usually on digital modes.The >> practical result was that I had to restrict TX power to less than 40Watts on >> most bands to avoid a burst from the Chicago Piano in the KAT. I had assumed >> an antenna/feeder problem and had changed every last connector, wire, balun >> and insulator in my system before asking for help from the Reflector Brains >> Trust. All of the other people who subsequently reported a similar problem >> made me feel a little better, and I also received a lot of diagnoses and >> practical advice which I have followed or will follow soon. One of the >> simplest was from Ron WB4OOA: Carry out a K3 Gain Calibration via the K3 >> Utility (I had to download the latest Utility version to make this work >> properly) then Install the KAT500 V1.42 Beta (Not quite as easy as it >> sounds). After this things were better, and my power setting on the K3 >> always appeared on the KPA500 wattmeter. I could now operate at higher power >> on some bands but had to stay below 40W on 40m. I had also adjusted the per >> band retune trigger SWRs upwards via the KAT500 Utility which also helped a >> little. >> >> I remain convinced though, that the basic trigger problem lies with the >> antenna system (an OCF multiband dipole) and I am continuing to work on this >> aspect using my analyser. Why it should have suddenly kicked off after many >> months of solid performance, and why changing everything hasn't yet cured it >> remains a mystery. My next steps are to try a choke balun on the feeder >> (parts now to hand) and to prune the antenna to get a better resonance on >> the bands of interest. Now if only this darn rain would stop! (I still think >> some tweaking of the KAT500 software might also help!) >> >> >> >> Ray Coles, C.Eng. M0XDL >> >> 10 Littlemoor Road, >> >> Weymouth DT3 6AA >> >> Tel: +44 (0) 1305 833699 >> >> Mob: 07831 516517 >> >> >> >> >> >> >> >> ______________________________________________________________ >> 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 Amateure Radio Operator N5GE ______________________________________________________________ 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
