Put your heads together and help K4JNY and myself come up with a
solution to this problem:
KLM 4 el 40m beam at 120 feet, 5 el 10 meter beam on a 28? boom at 125
feet on the same mast. 45G tower guyed with Phillystran.
The KLM antenna is (was) new in box and was built with all WØUN mods
and all DX Engineering hardware. It?s in the air, and exhibiting some
weird behavior.
According to our MFJ 259B antenna analyzer, the SWR is about 5:1 from
1.8 to 20 MHz. At 20 MHz, SWR slowly drops to flat, remains flat to
about 22 MHz, then rises back up to where it was.
Every 800 kHz to 1 MHz of spectrum, we can see the antenna impedance
dip from about 400 ohms down to about 12 ohms and then rise back again.
SWR does not vary when this happens ? indicates the same value of
about 5:1, until the dip at 20 to 22 MHz. We tried the same procedure
with an HF radio and got the same results.
The antenna does have some pattern, we can tell by rotating it and
listening to stations on 40 in different locations.
What we have tried so far: Swapped out the 4:1 balun with a different
4:1, then a 1:1 just for the heck of it. No change was noted. Nothing
appears to be disconnected or shorted and we were very meticulous when
assembling the antenna to not miss anything, use Penetrox on all
connections and NyLok hardware, etc. Different feedlines were tried ?
all act the same.
The only thing we can think of is that the 10 meter beam is severely
detuning/interacting with the 4 el 40. We tried shorting the 10 meter
coax out to see if it had any effect on the 40m ? no effect (which
makes us wonder if it is, in fact, this.)
What we plan to try next:
Rotating the 10m beam 90 degrees off the 40m beam.
If that doesn?t work, pull the 10m beam down off the tower.
Are we crazy? Or is there something we haven?t thought of? We?ve
been puzzling this over for the past two days and have decided we just
?don?t get it?. Any help?
Scott W4PA
=====
Always been the radio's child
Quick-to-smile precious baby
Search the dial and electrify
--Widespread Panic "Radio Child"
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