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Old March 15th 06, 07:56 AM posted to rec.radio.shortwave
Telamon
 
Posts: n/a
Default T2FD antenna opinions solicited

In article . com,
wrote:

N9NEO wrote:
I will hang T2FD in attic this weekend and have question about slope vs
bandwith. Well here is same post I just made to yahoo group. I have
some big dipoles for 75m and 160m, but I don't think they work so good
for SWL. I also have a very difficult time to climb up on roof
especially when cold. I'm a fraidy cat with heights( but no prob to
jump with a chute). This may be just an interm antenna till WX gets
better.

"Last time I was up in the attic about a year ago it looked like I
had about 12 foot of headroom. I was figuring I would put up a T2FD
about the full length 45 feet of attic and I could get a decent
slope. I was up there Saturday and now it looks like it's about 8
foot of headroom. I figure at the rate it's shrinking I better
hurry up and get the thing up while I can still stand up in the
attic.

So dilemma is length of antenna vs the slope. I can get a 20 degree
slope with a 23 foot antenna for about 14mc bottom end or a 30
degree slope with a 16 foot antenna for a 20mc bottom end. I am more
interested in SWL than ham bands. Antenna/attic is orientated along
a line parallel to 135/315 degrees."

I am looking for a comparison of the two potential installations.

Thanks & regards,
Bob
N9NEO


Is this a T2FD which you made (or are making) yourself, or is it from
RF Systems or B&W? I'm guessing home made since you talk about
changing the length.

I've used an RF Systems 45 foot T2FD at two different location with two
different angles because of the supports I had to work with, one maybe
20 degrees and the other at only 10 degrees!

Can't say that I noticed a difference. If anything, I'd say that I
pulled in more of the really low-power stations from Africa, South
America, Asia and the Pacific (omnidirectional) with it sloped at only
10 degrees all over the frequency range, from 60 meters to 19 meters
(never got anything that I'd consider low-power in the 16 meter band).
I did notice that I was able to DX in the 90 meter band only when the
angle was 20 degrees. Propogation always plays a huge part in whether
or not you receive a signal, but these results were pretty consistant.


I also believe that a big part in the exceptional signal-to-noise ratio
was the use of a Transi-Trap and a ground rod, even though the set-up
at 10 degrees had a pretty poor excuse for a rod (2 foot brass tube I
found at some hardware store, don't even know what it was supposed to
be used for).

I'd say use the full 45 feet with no slope.


Good advice.

BTW, where do you live? Its getting close to Spring everywhere here in
the States. Maybe six more weeks and you could set up your antenna
outside in relative warmth, if you're a Yankee like me :-)


Put up the attic antenna anyway. It would not be much trouble to put it
up and you might like the way it works. More antennas means more options.

--
Telamon
Ventura, California