Jim - Your personal e-mail bounced for some reason, hope you get this reply
through the reflector.......
Hi Jim,
Yes, it can be done! I've had great success with the shunt fed system on my
40 foot tower. I also have an inverted vee and vertical for 80/160, but the
shunt fed tower beats them all. I have to make a trip to Anchorage for the
next few days, but when I return, I'd be happy to try to answer your
questions on any issues you may have.
Basically, the antenna consists of a wire that is attached to a 2.5 foot
aluminum rod about 3 feet below the top of the tower. The wire drops down
toward the ground, and is attached to one side of a variable capacitor. The
center conductor of the coax connects to the other side of the variable
capacitor. Connect a heavy wire from the coaxial shield and connect that to
the base of the tower. That's about it. I used my Autek RF-1 meter to check
the resonance and adjust the capacitor for a match. You will note that the
resonant frequency will change with the closeness of the ground wire to the
base of the tower. I put my capacitor inside a plastic container and that
made it very easy to slide it in and out toward the base. Once I found the
"spot", I left it there and put some heavy bricks on top to keep it from
moving. That's all there is to it!
I hesitated doing this for quite awhile, but I'm really happy to have
finally made the leap! I'm not an antenna wizard, so it was pretty much a
give it a try situation. I'm sure you'll get it on the air too! Let me know
if I can answer questions....I'll be back on Sunday.
73,
Joe
WL7M
Fritz Creek, Alaska
At 02:53 AM 26-09-2002, Jim Leahy wrote:
>Hello all. I've always been under the impression that one had to have a 100'
>or taller tower in order to shunt feed it for 160m. Therefore, for years
>I've been fooling with long wires, random wires, low (25') windoms, slopers
>etc. without a lot of luck. Plus I'm only running 100w. But I happened
>across a recent thread where WL7M is using his 40' Rohn on 160/80m. Now I'm
>wondering if I can do this with my 40' freestanding tower and get better
>results with DX. Here's what I have: 40' freestanding tower, Mosley TA-33
>w/40m kit, 3 phillystran guy wires, each leg to a grounding rod and about 8
>random length radials buried from the tower base in conjuction with a W9INN
>all-band wire sloper. Is this a viable setup for using the tower on160m
>operation? If so, are there any good books/instructions on exactly how to do
>this? I'm also contemplating a Butternut HF2V 80/40 with the 160m kit which
>would end up being about 31' in length. Winter will be approaching fast and
>I want to get something different going on Top Band. Plus the fact that I've
>been inactive for about 3 years, I'm getting itchy! I've worked about 25-30
>countries with the various wire setups and 100w over the years. Looking to
>try something different. I'm currently using a Cushcraft AP8 vertical for
>80/40/WARC operation. That antenna, while serving me well when we lived in
>an apartment years ago, is really lacking when it comes to 80 meter
>operation. That is one of the reasons I'm thinking about the Butternut.
>Bottom line, I REALLY need to improve my 80/160m situation. Thanks for any
>help!
>Jim K2JL
>
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