I got the whip for 17m. I figure there is not much difference between a coil at the base of the whip and a coil inside the ATU. Neither one will radiate. So get a whip for the highest band you want to use and let the ATU provide loading for lower bands.
wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) > On Mar 23, 2016, at 8:44 PM, Tom Crayner <[email protected]> wrote: > > Wayne, > > Funny you should bring this up, I just received an MFJ-1899T today. Slapped > a counterpoise on it and at 6 watts running JT9 (in New Jersey) was able to > be heard (watching PSK Reporter) all the way in CA and Alberta. Just > worked a station in MN. > > I'm not even giving the whip a fair chance... I'm sitting in a basement > with it cranked up to the floor joist over my head, nestled between 4 foot > fluorescent tubes and metal duct work. It tuned 1.2:1... counterpoise is > connected to ground thumb screw next to antenna jack. > > I did groove a small piece of 2x4 for the right angle BNC connector to be > cradled on so all that weight of the telescopic whip doesn't damage the > jack... > > Can't wait to take this down to the shore in a few weeks and see what it > can really do without all the disadvantages I've placed on it tonight.... > :-) > > Tom, W2YF > > > On Wed, Mar 23, 2016 at 10:12 PM, Wayne Burdick <[email protected]> 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:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] >> > ______________________________________________________________ > 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 > Message delivered to [email protected] ______________________________________________________________ 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 Message delivered to [email protected]
