Michael Lawson wrote:

"Mark S. Holden" wrote in message
...
snippage

I wrote:

I went poking around the net for a while trying to
find out whether it's worth it or not, but I couldn't
find anything on the quality of the cable there. At
least any real data, that is.



Mark replied:

It's years since I bought RS cable, IIRC, the shielding
was loosely spiral wound instead of a full braid.


I dropped by and bought about 50 ft after taking a look;
it's a braid; not the tightest braid in the world, but it'll
do for the moment.


A fair number of people use RG-6 - it's 75 ohm impedance,
but the losses aren't likely to be meaningful. Home
improvement stores tend to sell quad shielded RG-6 at
a reasonable price.

The way I see it, noise is the limiting factor - so I'll gladly
trade a few db of signal strength for several db of noise
reduction.


Good point.

more snippage

I wind my own impedance matching transformers. It's easy. They
work well, and you don't need to twiddle knobs.

You need a few feet of magnet wire, and a #43 ferrite core. Here's
a link to a site with directions:

http://www.kc7nod.20m.com/new_page_1.htm

I recently bought over 100 #43 ferrites that are a little smaller

than

the one in the plans, but they work fine. If you need one, contact
me direct - I'll sell you one for a buck postpaid.


The 9:1 converter ought to work for 50 ohm cable too, with an
adjustment in number of loops, I'd imagine. Time to crack open
the books and reacquaint myself with inductance again.

Thanks for the offer; I ought to have a couple of 75-300 converters
around, so I'll see what I've got first.

--Mike L.


Good luck with it.

I bend the wire so it's next to itself for the first ten turns, so I can
wind the primary and secondary at once.

I use a hot glue gun to tack the wire down to the ferrite when I start
to wind the transformer, and as each winding ends. (3 drops total)

Until I installed my first one, I never would have believed how much of
an improvement they make.