Doug,
If you have the room, here is an alternative that I am using now at ZF9CW.
I believe this would be better than a coil at the base.
Make that vertical your 160m transmit antenna by adding two wires attached
to the top and going out as far as you can so the ends are as high as you
can get them. Make it symmetrical with the wires going East/West or
North/South, etc. Those wires will be 60 feet plus or minus each.
For 80m have a quarterwave wire with a good insulator spaced a few feet out
coming off the vertical at 45-50 feet up. That wire can come out from the
vertical by 10 feet or more and then back to the base. Use separate
feedlines and same radial field. Match with a hairpin for each antenna.
My 80m vertical looks a lot like a > sign but the top line is longer than
the bottom one. I am just guessing mine comes from about 50 feet, comes
down to about 20 feet up and 20 feet out and then back to the base.
You could put a vacuum relay at the top to switch the wires out for 80,
which I have done, but I like the flexibility of current scheme better.
If you are going to make a coil and have modeling software, Hamwaves
Inductance calculator is a good tool. Coils are nice but can be a pain to
weatherproof.
73... Stan, ZF9CW
On Sat, Nov 17, 2018, 12:04 PM doug dietz <doug49707@gmail.com wrote:
> Gentlemen,
> I have been lurking in the background for over a year there have been some
> excellent learning possibilities.
> Thank you all. now on to my question.
>
> I have a 1/4 wave vertical (about 66 feet) for 75-80 meters I would like
> to try and make it resonate on 1.825. If I put the analyzer on it I don't
> understand the reading.....I know the swr is bad on 160 because the
> kpa-1500 will not match it. If possible I would like to add a coil at the
> bottom with a relay to switch in and out. Any ideas length of wire,
> diameter, of coil, and size of wire, for 1500 watts I am not worried
> about receive only transmit.
>
> Doug WD8Z
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