On Sep 10, 2:47 am, Richard Clark wrote:
On Sun, 09 Sep 2007 22:51:54 -0400, RJG wrote:
I bought 2 Slinky's to put a Slinky antenna together, and would love to get
comments and suggestions, (construction detail tips, care and feeding, etc.)
from anyone who has tried this type of antenna before.

I live in a second floor apartment and have limited HF antenna options. I
would love to hear recommendations for any other HF antenna designs that
would work well in this type of setting.

Classic wire-wound, air-cooled resistors.

You could do better with the various 1 meter diameter loops sold
commercially. Some might suggest mobile screwdriver designs clamped
to your balcony railing, but that isn't really the same sort of metal
bulk equivalent to a, say, Chevy Suburban which would be the principal
radiator. On a comparable price basis, the loops will be a better
investment for 40M and up (I don't recall any that suggest they cover
80M and certainly 160M is beyond the realm).

A simple test for small (for their wavelength) antennas is to measure
their bandwidth. We will take the Slinkies as an example (and
certainly cheap enough to test this statement, and to see how they
perform both). A small antenna that would be efficient will also
exhibit a high Q. The loops mentioned, as I recall, generally exhibit
5 to 10KHz bandwidth. For the most part, they exhibit some of the
better efficiencies (although not as high as a standard dipole).

The slinkies stand to have a wider bandwidth due to their loss (small
wire AND steel wire). Initially, this may seem to be quite
attractive, and if you ignore the loss, they may serve your purpose
quite well (SWR and Loss are not always limitations to enjoying the
hobby). As I said, cheap enough to simply plunge on and worry about
efficiency later.

Tune-up can be as simple as stretching/compressing the coils until you
achieve a match (at least that has been my experience). If the
frequency is too low, add more slinkies. If you want to beef up the
efficiency with a slinky, make it(them) part(s) of a center loaded
element(s). Unfortunately that means more room than you have in your
apartment situation.

73's
Richard Clark, KB7QHC

Speaking of loops, does anyone have experience with any of these:

http://www.universal-radio.com/catal...ants/4465.html

A Slinky dipole is an excellent illustration of the fact that we use a
lot more power than we need to. As some folks have pointed out, most of
the power you send to it ends up as heat. As others have noted, you can
still talk to lots of stations with it. If everybody would use one, it
would drop the QRM level a lot.

Roy Lewallen, W7EL