Hi John -

I checked your link... It worked, and the article is excellent!

The antenna described looks very neat, and would be a
fun project for someone who enjoys home-brewing.

For someone preferring a minimum of home-brewing, W9INN
has about eight similar models (SSD series and MDX series),
ranging in length from 46 to 71 feet. I haven't tried them all,
but my experience with his MBD-847 and SSD-021-5 antennas
has been excellent.

73, Ed W6LOL

"John DeGood" wrote in message
...
I tried to find the specific antenna you are considering using
your links, but I wasn't able to do so with a reasonable amount
of effort.

Sorry, my ISP recently ceased operation. You can find the page
originally referenced, at least in the near term, at:

http://users.tellurian.com/jdegood/coaxtrap/

It's simply a six-band trap dipole. The 5 pairs of coaxial-cable traps
provide significant physical shortening, although to fit in an attic
some or all of the outermost (80 meter) portion will probably have to be
run at right angles to the main dipole. The advantages of such a
resonant antenna include a decent match to a coax feedline and no-tune
operation (but over limited bandwidth, a side-effect of the reduced size.)

Another alternative for multi-band operation in a restricted space
situation such as an attic is a physically shortened dipole in
conjunction with a tuner and open wire feedline. For details, see:

http://www.arrl.org/tis/info/HTML/li.../limited1.html

73,

John NU3E

Ed Senior wrote:
Actually, I rather LIKE the switchable-length transmission line idea.
Could you refresh me on many different lengths do you find you need to
be able to get the SWR below, say, 2:1 at every point in those 8 bands?

I use 5 different lengths in a binary pattern. It's described on my
web page. 0-32 total feet is needed to cover all of 75m.

(I think we talked about this in an earlier thread, but I don't remember
all the details.) How do you stow the tuning lengths, and how many
physical switches (or plug-ins) are needed? When you do a typical
band change, does "a couple" of switch operations literally mean two,
or several? Any safety issues with the switches if you're running power?

The loops are about six inches apart on the outside of my window. I have
five 4PDT knife switches but I don't bother with the lower two on 75m.
I don't bother with the upper two on 10m. The knife switches handle 500
watts just fine.
--
73, Cecil http://www.qsl.net/w5dxp



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