View Single Post
  #12   Report Post  
Old June 9th 07, 09:33 PM posted to rec.radio.amateur.antenna
Jimmie D Jimmie D is offline
external usenet poster
 
First recorded activity by RadioBanter: Feb 2007
Posts: 287
Default Shortwave Antennas


"Al Dalton" wrote in message
...
There are several things to consider. I don't know how much you know
about antennas, but I see you have done some research, so that's a
good sign. Hopefully you will understand what I am about to say.

My father, also an avid SWL, used to use a long wire antenna. Then
one day he bought an antenna tuner kit for $10 about 15 years ago. It
really wasn't much, just a couple of small capacitors and a piece of
laminated wire he had to wrap around a pill bottle. He added his own
bypass switch and was excited to show me the difference the tuner made
to his signals.

I wasn't as surprised at the results as I was his initiative to buy
and build the tuner kit.

Anyway, he moved and we ran a wire around his attic about four trips.
The wires were spaced about 3 inches apart and just looped the attic
from corner to corner. I don't know how long it was, but it turned
out to be much better than the long wire. He hooked up his tuner and
radio and used it until he moved out. It was extremely sensitive.

My suggestion, for SWL, is to run as much wire over as large an area
as possible. If you are limited to indoors, I suggest the attic idea
if possible.

If you don't have the room, look for the largest area possible to
spread wire. If you find the best you can do is the broomstick idea,
(I assume it is a dowel wrapped with wire) then you may have to use
that. The larger the diameter, the better.

Research the antenna tuners. You don't have to worry about power
levels, so any small capacitor will do. Make one, or buy a kit and
add it to your antenna. You won't regret it.

Dad's tuner consisted of a pair of tuning capacitors out of two small
AM radio receivers with a piece of enameled wire wrapped around a
large pill bottle. The wire was tapped twice the distance of the
previous tap, for example, if the first tap was at the 4th wrap, 8
turns later, the third was 16 turns from the previous, etc.

There are several home-brew plans on the internet. I highly recommend
it if you are wanting to pull out the weak signals.

Good luck, I hope you find what you need and enjoy your listening.

buck
N4PGW

I do know a fair amount about antennas and tuners. I'd have the no code
tech license if I could remember the stuff you really don't need to know
(for the test). My memory just isn't good enough, and memorizing some of
that stuff isn't even relevant to whether or not we know what we're doing.

As I understand it, an antenna tuner is the single most important thing
involved? That makes sense. A tuner adjusts the overall resistance of the
circuit (impedance). Right? I have looked up everything I could find and
found a tuner for 60 bucks. I can't spend that on a tuner right now. I
should probably make one.

Are there any plans (w/parts list) on the Internet? Where might I find
them? Thank you.

Al


Just abot any decent book on ham radio has plans. My older tuner was very
similar to the big KW tuners but the coild used a sling tap instead of a
roller inductor and he caps were small receiver typed instead of vaccum
variables. This made it very cheap.