Hello folks. With the demise of my tree-mounted 80m delta loop, and the
clear superiority of my new 40-2CD over my old 40m 4-square, I'm
investigating what it would take to convert the 1/4-wave spaced 40m 4-square
to an 1/8-wave spaced 80m 4-square. This would involve extending the
elements from about 32 feet to about 64 feet, replacing the phasing lines
and hybrid coupler, and using the same radials (60 35-foot buried radials
per element.) In other words, the idea is to get from here to there as
quickly, cheaply and effortlessly as possible.
K4SQR of Comtek systems says ELNEC shows the close-spaced array to have 10
dB F/B and 4.9 dBi gain. I get similar results with EZNEC. While this isn't
stellar, it's quite a bit better than the delta loop, especially if I can do
it with minimum effort and cost. (BTW, K4SQR also says it's OK to feed the
system with one of their hybrid couplers, as long as the phasing lines are
1/4-wave long at 80m.)
So, my questions:
1. Has anybody out there attempted to do a conversion like this? If so, how
did it work out?
2. Has anybody out there attempted to do an 1/8-wave spaced 4-square? If so,
how did it work out?
3. Are the 1/8 wave radials going to result in much lower efficiency (bear
in mind that there are a lot of them)?
and most important:
4. What's the easiest, cheapest way to extend the elements?
Each element currently consists of seven 6-foot telescoping pieces of T-6061
drawn aluminum tubing, ranging in size from 2.0" in diameter at the bottom
to 1.25" in diameter at the top. Each section is slotted at one end and
connects to the next smaller size with a hose clamp. Each element is mounted
on an 8' long pressure-treated 4x4 post (about 3 feet in the ground and 5
feet above ground) with standard pipe clamps. To install each element, I
nested all the sections, affixed the element assembly to the post, then
stood on a ladder and extended each section in turn (starting with the
smallest, of course.) No guying was necessary. Note that the feed points are
near the ground (i.e., the array does not use raised radials.)
I would like to re-use the existing aluminum and posts if possible. I would
also like to be able to put the elements up myself, or perhaps with one
other person, and would like to avoid complicated schemes involving winches,
tower sections, etc., and transport of long pieces of metal. I'm not looking
for a design that will withstand the next hurricane -- if it can stand up to
a 50 MPH wind with simple guying at two points (Dacron rope), that will be
fine.
Any ideas? If so, please indicate sources of any recommended parts.
Thanks & 73,
Dick WC1M
_______________________________________________
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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