On Aug 22, 12:34 am, wrote:
On Aug 21, 5:11 am, Denno wrote:





Hi All. I recently received a Grundig S350 as a gift from my son.
They were on sale at the time, and after reading all the reviews he
could find on MW DX, decided it was the best "bang for the buck" at
that time.

I love this radio! Like I said, it's primarily for AM DX.
Unfortunately, I use it in my basement office were the reception is
spotty at best. Picking up local stations is no problem, but DX'ing
from inside an 8" thick concrete foundation is out of the question.
Above the basement, such as using the radio on the second floor, I can
actually pick up Montreal stations 300 miles away with no external
antenna!

So I need a remotely mounted, external antenna to get full use of my
radio from the basement. My options are limited: I don't have a good
yard for a long wire or beverage. Whatever I use will be confined to
the roof top or inside the house. I have a small DC motor ideal for
rotating the antenna remotely from the basement, but any tuning
capacitors would have to be near the radio.

What I would REALLY like to do is put together the longest ferrite bar
possible, with an optimum number wire turns around it, connected to a
coax which would run down to my office and clip into the external
antenna connections on the radio. A separate control line will also
run down there for rotating the antenna.

I have not been able to find much info on external ferrite bar
antennas. Could this be because there is no advantage to ferrite over
an air core antenna outside of the radio?

So my question(s): Are there any plans or illustrations for an MW DX
ferrite bar antenna available anywhere? (Web, ARRL pubs, etc) Is it
just a matter of connecting 2 or 3 feet worth of ferrite bars with
epoxy and then winding as many turns of light gauge wire as possible
around it? Do I need any sort of balun or isolation transformer?
(Lightning protection is not an issue. I always disconnect my
antennas when not in use)

Thanks,
Denno

http://www.stormwise.com/page26.htm

I've fiddled with loops and a North Hills transformer for the balun.
Still not as good as a wellbrook, but interesting from a hacking
perspective. Ebay has North Hills transformers from time to time, so I
wouldn't pay real money for one.- Hide quoted text -

- Show quoted text -

North Hills Signal Processing - Wideband Transformers
http://www.northhills-sp.com/product...nsformers.html