Topband: A little assistance needed with an attempt at a T antenna

[donovanf at starpower.net]

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 <armstrmj at aol.com>  
>Subject: Topband: A little assistance needed with an attempt at a T antenna  
>To: "topband at contesting.com" <topband at contesting.com>
>
>
>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.