Antenna
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Antenna
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As described on the Home
page,
for my main station, I'm using a HF multi-band mobile vertical whip
(Moonraker Intruder III), which is mounted simply on a magnetic mount,
which is in turn sat on a metal filing cabinet. There is a metallic
'baking
tray' between the mag-mount ant the filing cabinet, which has a couple
of simple 'speaker' wire radials bolted to it and draped out around the
room floor (nothing
fancy or special).
Whilst
this arrangement tuned up pretty well from 80m to 6m (and even
2m),
I wanted to be able to work 160m if possible, as the local weekly
'chin wag' was on that band. So I began thinking... if the Intruder
uses base
loading coils to cover 80m up, couldn't I just construct an extra coil
at the bottom to increase the overall effective length?
And that's what I've
done,
firstly with a basic wooden frame with some garden plant wire wound
around, and to my amazement it 'loaded up' on 160m!
I have since rebuilt it with
better (thicker) wire and more solid wooden construction, and have
also added a 'shorting socket' at the base of the '160m coil' so that
it too can be taken out for 80m and above.
This
arrangement has stopped 2m working, but as you will read later, I
have constructed a separate 2m vertical to plug into either my Yeasu
FT-290R, or the Yeasu FT-767gx 2m module.
My
latest thought is to try two of these multi-band mobiles in a
horizontal dipole arrangement, with one of these in the middle on some
sort of non-metalic stand (and still inside on first floor):
It
won't cover 160m of course, but be interesting to see what effect it
has on Digi-coms and noise levels compared to the current single
vertical. Need
some help from Santa to fund this though :o)
2015 update: Bought a second Intruder III, plus both straight and 'V'
shaped center connectors for testing to see which performed best.
Unfortunately, I miscalculated the balance of the set up I'd created
(Used a section from an old fishing pole with the 'V' at the top), and
the whole lot toppled over, breaking the top sections of both
Intruders... gutted wasn't the word...
Although I have managed to repair the Intruders, I have for the time
being gone back to my original set up (until i calm down a bit :o)
Having gone back to my original set up (i.e. vertical with the 160m
base coil), I decided to try getting 60m working by adding an extra tap
point along the first coil. Initially I got it wrong, but by trial an
error I found a point where I could get a SWR of 1.6 by whip
adjustment. And have already had 3 60m JT65 contacts... chuffed. Also
had my first JT65 contacts on 6m in June 2017... can't believe my luck
:o)
I have
also been 'dabbling' with antenna designs made from ribbon cable, and
have constructed a 'mighty wide' for 6m which seems to have an
unbelievable SWR across the whole UK band, plus a 2m Slim Jim based
upon a Gloucester Amateur Radio and Electronics Society design, which
out performs anything I had (but that wasn't much).
Links to design and construction sources:
6m
Mighty Wide is strung between rafters by fishing line, and the 2m Slim
Jim is tape to part of an old fishing pole.
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