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Channel Jumper · December 28th 14, 05:39 PM

Quote:

Originally Posted by

Tom Horne wrote:
I am using a Yaesu FT-1000 with a folded Dipole that is Ninety Feet in leng
th. To be clear this is literally a folded dipole were the two ends are fo
lded back to the middle and fed at that point. This is NOT a terminated fo
lded dipole! It consists of a loop of fourteen gauge copper wire that is On
e Hundred and Ninety Two feet long that is strung on either side of one foo
t long insulator rods. the opening in the loop is at the feed point locate
d at the middle of one side of the loop. From the feed point three Hundred
Ohm window line runs to a Six to One ratio BalUn. The internal tuner of t
he Yaesu FT-1000 tunes the antenna fine until I attempt to tune up on One S
ixty, Eighty, and Forty Meters. The results I get on those three bands are
erratic. Some times the tuner works fine and sometimes it shows a high SW
R warning and refuses to transmit. I was hoping that someone who knows how
to model antennas might be willing to run the numbers for me and advise wh
at ratio of balun is likely to bring the antenna consistently into the Yaes
u FT-1000's internal tuner's capability.

--
Tom Horne W3TDH

Your numbers don't make sense. If there is 192 feet of wire with a spacing
of 1 foot then it should be 95 feet long, not 90.

Also you did not say how high it is, which will make a difference.

For 95 feet long and in free space I find:

Resonace at 2.48 Mhz 290 Ohms.

Impedances at the band edges:

1.8 678-j3426 3492 Ohms @ -79deg
2.0 313-j1436 1469 Ohms @ -78deg
3.5 5143-j2126 5565 Ohms @ -23deg
4.0 287-j1550 1576 Ohms @ -80deg
7.0 1143-j1742 2092 Ohms @-57deg
7.3 494-j616 789 Ohms @ -51deg

If you increase the total length to 124 feet, it becomes resonant at 1.9
Mhz 290 Ohms.

Again, the actual height above ground is going to make a difference.

Download the free version of EZNEC; it can easily show you all this stuff
and a folded dipole is trivial to model.

--
Jim Pennino

Thats what I got Jim also.....

So the question is - WHY?

If the OP knew that it wouldn't be resonant, why did he build it?

My guess is that is the distance between the trees in his yard / field or between the trees and the tower he has by his house!

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