On Feb 26, 9:44*am, wrote:
On Feb 26, 9:54*am, Kevin Alfred Strom
wrote:





D. Peter Maus wrote:
On 2/26/10 08:23 , Steve wrote:
On Feb 25, 2:43 pm, *wrote:
Hi - I have a portable radio I am tinkering with, so far
superficially. *It has a ferrite bar inside for AM and SW reception up
to 6 MHz with no provision for an external antenna. *The ferrite bar
works great on AM, but as you might guess, the SW reception is short-
changed.

To start with, I was thinking of getting another ferrite bar about 10"
long, wrapping a few turns of wire around it (probably try several
turn values to see what works best), mounting it on the back of the
radio broadside to the internal ferrite bar, and then hooking the
leads up to my external wire antennas. *Any reason why this would or
would not work for better reception near 4-6 Mhz? *Would an end-to-end
configuration be better?

Thanks,
Bruce

I don't know whether it will work or not, but here's a source for some
seriously big ferrite rods:

www.stormwise.com.

* Or this:

https://www.amidoncorp.com/categories/6

If you don't mind it looking strange, it would probably work just as
well to wrap a few turns (experiment with the number and
orientation) of wire around the outside of the radio and then attach
the ends of the wire to your external antenna.

Better yet, open the radio and wind a few turns around the existing
rod, then bring the ends out to a terminal strip or connector.

With every good wish,

Kevin, WB4AIO.
--http://kevinalfredstrom.com/-Hide quoted text -

- Show quoted text -

* * * *A word of caution! *Be extra careful with the existing
rod(loopstick). The wires on it are so fine that it may brake off very
easily. *RShack used to carry thin enamelled wire of various sizes.
Experimenting is fun and sometimes the results are much better
performers than ready made products. Actually, there is a company
called Palomar Engineers in California which speacialized in small
loop HF antennas,ferrite cores of various types and rf baluns.Fairly
high quality products.- Hide quoted text -

- Show quoted text -

Thanks, Arthur - I noticed that when I opened the radio up - those
connecting wires are no thicker than spider webs. I certainly agree
with Kevin's idea about trying some twists around the internal
ferrite; I'm sure it would be quite helpful, but the reason you just
suggested gave me pause.

Anyway, I think first I will try an external parallel ferrite bar
linked to my outdoor antennas, maybe with a variable cap for tuning,
and see what happens. That certainly can't hurt, and who knows?
Maybe it'll help...or not! I noticed a specific ferrite bar item at
Stormwise that might be the ticket, with recommended number of turns
for various freqs of interest.

BJ