Stll in trouble with his antenna, IV3TAN asked me to post his
message to the Tower Talk reflector hoping that someone can
If possible send answers directly to him firstname.lastname@example.org
and not to me or to this reflector where he's not subscribed.
Da: Alberto Annesi [IV3TAN]
I hope that you'll undestand my poor English!!!
My name is Alberto Annesi (IV3TAN) and about
2 months ago i bought a second hand (but new!!!) 2 element for 80 meters
the 80M2 model, with the optional high power balun (10 kw).
I changed the SO239 female connector with a 7/16 professional connector
I assembled the antenna with extremly precision like a manual described.
After one mounth we put the antenna on top of the tower (@110 ft) but....
the SWR on 3.780 MHz and 3.525 MHz was very very high.
I measured the SWR after a section of half wave 50 ohm cable ( x velocity
my Autek Research RF-1.
I measured also the SWR after a section of one wave 50 ohm cable ( x
with my RTX Icom.
Both instruments gave me the same results:
at 3.525 MHz and 3.780 MHz the SWR was about 4:1
at 3.640 MHz and 3.890 MHz the SWR was 1,1 : 1 !!!! 100KHz more than the
After these tests we decided to measure the front to back and front to side
A friend of mine have an half-wave, horizontal 80 meters dipole @80 ft/h
2 miles far away, and from top of my tower you can see his antennas.
at 3.525 MHz and 3.780 MHz the F/B was 2 S-units (10/12 dB ...good) and
F/Side was over 6 S-unts
(30/36 dB ...good).
on CW 3.525 MHz frequency the S9
dropped to S0....
When i trasmitted (with the antenna tuner) the results were the same.
at 3.640 MHz and 3.890 MHz the F/B and F/S were absolutely poor. No F/B and
only few dB of front to side.
At that time, i thouhgt that the measure of the antenna had to be correct
but i tried
I changed the position of two bridges of the linear loading of the radiator.
About 12 in. for each part. The SWR at 3.525 and 3.780 was perfect 1,1 : 1
i didn't have any Front to Back and Front to Side Ratio.
So i put two alumin stubs of 24 in. in the final section of the reflector
the result was the same: NO F/B and very very poor F/Side.
I think that the original measure (like a manual describe) are OK but i
that i have a problem with the impedence of the antenna.
If i change the lenght of the hairpin ( in the last 10 in.) i don't see a
alteration of my value.
I pulled up and pulled down the antenna a dozen of times.
DO YOU HAVE A SOLUTION???
WOULD YOU PLEASE HELP ME???
Many thanks. Alberto Annesi IV3TAN
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