Robin-
When I put up an Inverted V, I always add 3-feet of wire to each end of
the antenna. Then when you check the SWR and its too high, you can pull
some of each leg of the antenna through the insulator and loosely wrap
in around the "shortened" leg. Try it again and you will probably see a
lower SWR. Do it again and check it again. You will find the task of
tuning an Inverted V takes a very short time.
I remember doing this for a new ham who was putting up a 10M Inv V. AS
I shortened the antanna by 10" or so, he said, "Gee, I thought I was
supposed to shorten the wire a half-inch at a time." Get the idea?
Since you don't cut the wire, you can try whatever you want. When done,
you can then make it neat with tight wrapping of the surplus wire and
cutting the excess off.
I have been using a 80M, 40M, 30M Inverted V whic was easy to do using
the rig's SWR indicator. After a lot of years the 14 guage wire broke
on 40M, so I am redoing it and adding 12M to the mix.
Hope this helps.
73-
Fred, W6TKV
Robin Midgett wrote:
>
> Hi,
> My attempts to make an inverted V resonate on 80m are not meeting with
> great success. I've put up inverted V antennas before (10m & 40m) and they
> worked very well...not so in this case; 2.8:1 (feed point fully up) is the
> best match I've seen yet. I'm hoping some of you more experienced will have
> some constructive input.
> Here's the configuration:
> 130' of Rohn 45G, on fairly flat, level ground with a 24" (out from the
> tower) aluminum stand off bracket at the 60' level. A rope and pulley rig
> is used at the end of the stand off to haul the feed point of the V up to
> the 60' level. Each leg of the V is ~62' long, and there is ~ 80-90
> degrees between them. The ends of the wire (14 ga. stranded) are formed
> into a loop, which is where a small piece of rope attaches and anchors to a
> stake in the ground. Pretty typical stuff, from all I've seen before.
> The tower is guyed at 30' intervals to posts 85' from the tower base, so
> guy wire lengths (all 1/4" EHS) are 90', 104', 124' & 127', no insulators
> on any of them.
> With the feed point pulled up all the way, ~3:1 is the best match I get. If
> I lower the feed point to ~50', and the ends of the wires are drooped onto
> the lawn, the match improves to ~1.8-2:1.
> I'm using a MFJ-269 to make the measurements. I find really good matches
> (~1.5:1 or better) at 12 MHz, and odd multiples up the bands.
> I've changed the coax, no help. Removed the coiled coax choke; no help.
> Checked continuity from shield to end of one wire, OK; from center pin to
> end of the other wire, OK; no shorts, either.
> Is this possibly a case of guy wire coupling/interaction? Might raising the
> feed point to a higher level help the match? Should I extend the distance
> from the side of the tower to the feed point?
> Thanks,
> Lost in H.F....going back to VHF+....Robin KB4IDC
>
> "Success is the ability to go from failure to failure with no loss of
> enthusiasm." -Winston Churchill
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
> questions and ask for Sherman, W2FLA.
>
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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