Hi Mike, You should enjoy much improved DX performance with an inverted-L and ground radials than you're having with your off center fed dipole (OFCD). I recommend you simply use an inverted L rather than a T vertical. The T vertical offers little advantage if the T top isn't nearly symmetrical.
An inverted L will work just fine, many of us use them with excellent success. Try to make the vertical wire as tall as possible. Good luck! 73 Frank W3LPL ---- Original message ---- >Date: Fri, 4 Jan 2013 06:56:07 -0700 >From: Mike Armstrong <[email protected]> >Subject: Topband: A little assistance needed with an attempt at a T antenna >To: "[email protected]" <[email protected]> > > >Hey guys and gals, >I have a question: I have an OCFD that is about 130 feet long, end to end. It >is Off Center Fed at a current node for 15 meters, which is the band it was >designed for. Ends up that it tunes easy on just about any band, albeit with >open wire feeders and a tuner. It works very well for 10, 15, 17 and 20, >since the major lobes are directed where I want them. Although anecdotal, >what I can say is that I rarely have to make a second call to any station I >want to work on those bands..... which was a very real surprise considering >its simplicity. it is 40 feet high, which is not great, but it is as good as >I can do. I have actually tuned it to 160 during a contest last year and >ended up working (and thank you guys, CONFIRMING) a total of 9 >countries....... Japan, Australia and Chile included..... Which REALLY blew my >mind. But I digress...... Suffice it to say that for the higher bands, I am >very happy with it. > >I want to try to use it as a T antenna and lay out some radials. I do have a >limited space situation, from a 160 point of view, with the typical postage >stamp lot. I got the OCFD as long as it is by placing a good portion of the >antenna in my Mother-in-Law's property and terminating the far end in one of >her palm trees. I needed to say that because some folks might wonder how I >put a long antenna on a postage stamp lot..... I didn't..... It is 2 postage >stamps side by side. However I can't go crazy and lay antennas everywhere on >her land. So...... After all the preliminaries, I want to try the T, but it >definitely struck me that the antenna, being OCFD as much as it is, is >definitely NOT balanced side to side. Would this have a negative impact on a >T? Would it be better to call it an inverted L and just forget the short >side, including that side of the transmission line? I am thinking that the >latter is probably the way to go, but if a T would work in such a strange! ! >c onfiguration, I would prefer to use the extra wire rather than having it sit >idle.... LOL. > >Anyway, thanks for taking the time to read this tome..... Any response would >be welcome, especially if anyone has actually done something similar with an >OCFD that is so "unbalanced." Ay anecdotal data concerning performance is >welcome, as well...... If you are still using it, because it is a decent >performer on 160, that matters because you guys are so willing to alter >antennas if they aren't doing EXACTLY what you want them to...... He he he. > >Mike AB7ZU > >Kuhi no ka lima, hele no ka maka >_______________________________________________ >Stew Perry Topband Distance Challenge coming on December 29th. _______________________________________________ Stew Perry Topband Distance Challenge coming on December 29th.
