Back around 1962, I was working on the Syncom satellite program at Hughes
Aircraft. NASA wanted us to make some satellite transponder simulators so
they could check out the ground stations. The plan was to take some of
the 'less than perfect' hardware and package it up in a metal box.
Unfortunately a lot of that stuff wasn't very stable, particularly the
varactor multipliers. To make things worse, they used TWT amplifiers
(in a separate box) followed by a 10 watt attenuator which brought the
output back down to about the same level as the drive to the TWT. We
ended up lining the boxes with steel wool along with a lot of metal
tape to seal the seams, etc., and it did seem to help (a bit).

I remember the steel-wool balun story and wondered at the time if perhaps
it was merely absorbing some of the current on the outside of the coax.

73, Bob N7XY

On Sun, 14 Aug 2005 23:34:48 -0400, Fred W4JLE wrote:

Walt, I just went back and checked some old notes. I show I wrote a letter
to the editor on the steel wool balun in 1977. I know Roy said 1993, but I
"Walter Maxwell" wrote in message
...
On Sat, 13 Aug 2005 18:00:21 -0400, "Fred W4JLE"
wrote:

You might be an old time if you can answer the following, with out diving
into your library.

Which of the following is NOT a rectifier?
a. 3B24
b. 80
c. 3C24
d. 6H6

Steel wool was once touted as a good material to make which of the
following?

a. Choke Balun
b. AF shielding
c. Linear capacitors
d. Radials for short virticals

Feel free to add your own favorite...


Good ones, Fred, 3B24 and 3C24 are not rectifiers.

However, some moron claimed in QST that steel wool was just as good as
ferrite for making choke baluns, but I've forgotten who the lunkhead
at the League was who believed him, and allowed stupid idea to be
published.

I complained to the League editors, who unbelieveably said 'Prove It'.
So I bought some steel wool and made two back to back baluns with it
and made measurements of common mode currents. The measurements proved
that the steel wool had absolutely no choking effect.

I reported the results of the measurements to the editors at the
League, but I can't remember whether they did anything about refuting
the original incorrect material. Perhaps your memory is better than
mine on this issue.

Walt, W2DU