Use one of the KX3's thumbscrews. We relieved the paint on the chassis at these points so you can use them for counterpoise wires or ground.
Wayne N6KR On Mar 29, 2016, at 5:14 AM, "Barry N1EU n1eu.ba...@gmail.com [KX3]" <kx3-nore...@yahoogroups.com> wrote: > > Probably a dumb question, but any suggestions on how to connect counterpoise > wires using the MFJ-1820T? The loaded whip terminates in a male BNC, which I > assume is intended to connect directly to the KX3 antenna jack. It's not > obvious to me how to add counterpoise wires??? > > Thanks & 73, > Barry N1EU > > On Wed, Mar 23, 2016 at 10:12 PM, Wayne Burdick <n...@elecraft.com> wrote: > Hi all, > > I've been using an MFJ-1820T telescoping 20-meter whip for a few months. > Considering its length (48"), results have been excellent. I typically use it > with the KX3 on a picnic table at 15 W (with an external battery), or > hand-held at 3 to 5 W (internal battery). > > During the ARRL DX contest I worked many countries in CW and RTTY modes, and > have also had a number of longer QSOs on 20-meter SSB. Of course at these > power levels, with an electrically short whip, good band conditions can't > hurt. > > I prefer a 25' or so wire-in-a-tree antenna when there's time. But when I > need a quick deployment antenna that weighs very little, I pull out the > 1820T. Note that you *must* use at least one counterpose wire. More than one > helps, but all of the QSOs I described were made with a single 13'-long wire > laid out on the ground. With no ground wire, you'll be down some 15 to 20 dB > in transmit mode. > > Since the 20-meter results were so good, I also bought the whips for 40, 17, > 15, and 10 meters. 40 meters is a rough ride at 48", but I was still able to > check into daytime SSB nets all over the west coast running 10 W. On the > higher bands, results improve as you go higher in frequency. I worked a few > JAs on 15 meter SSB running just 1 watt. > > A traditional problem with such antennas is that the the SWR can sometimes be > unexpectedly high, requiring that you micro-adjust the telescoping length > and/or adjust the length of the counterpoise wire. This is completely > unnecessary if you have an auto-tuner available. In particular, the KX3's ATU > can quickly match any of these whips over their full target band. In a pinch > the ATU can also match a given whip on adjacent bands. In the DX contest > mentioned I tuned up the 20-meter whip on 17 and 15 meters as well, and made > a few Q's there, despite the losses due to off-resonance operation. > > These whips can handle a surprising amount of power. They're rated to 25 W, > but I ran 50 W through the 20-meter version for several minutes without > damaging it. Some other compact whips I've tried overheated quickly even at > 10 W, including some of the Maldol models. When this happens, the SWR goes up > and stays up until the coil cools down. > > Caveat: Always use a full-size antenna when possible. But if you've just > crested a new hill and only have a couple of minutes to see if the RF really > is greener on the other side, this is an excellent choice. > > 73, > Wayne > N6KR > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to n1eu.ba...@gmail.com > > > __._,_.___ > Posted by: Barry N1EU <n1eu.ba...@gmail.com> > Reply via web post • Reply to sender > • Reply to group • Start > a New Topic • Messages in this topic (2) > > VISIT YOUR GROUP New Members 21 > • Privacy • Unsubscribe • Terms of Use > . > > > __,_._,___ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
