External ferrite bar for 2-6 MHz?
 

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

External ferrite bar for 2-6 MHz?
 

On Feb 25, 2:43*pm, bpnjensen 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.

External ferrite bar for 2-6 MHz?
 

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

External ferrite bar for 2-6 MHz?
 

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/

External ferrite bar for 2-6 MHz?
 

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.

External ferrite bar for 2-6 MHz?
 

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

External ferrite bar for 2-6 MHz?
 

"bpnjensen" wrote in message
...
On Feb 26, 9:44 am, wrote:
On Feb 26, 9:54 am, Kevin Alfred Strom
wrote:

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

Several websites have info on this. Both ferrite and larger air core loops.
I don't have the links handy, check Bill Bowden

External ferrite bar for 2-6 MHz?
 

On Feb 26, 5:06*pm, "bw" wrote:
"bpnjensen" wrote in message

...
On Feb 26, 9:44 am, wrote:

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

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

Several websites have info on this. Both ferrite and larger air core loops.
I don't have the links handy, check Bill Bowden

Thanks, bw, I'll check that right now :-)

External ferrite bar for 2-6 MHz?
 

On Fri, 26 Feb 2010, Kevin Alfred Strom wrote:


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.

And that's all that's necessary.

The winding of wire around the radio, the external coupling loop, those
are all constructs to deal with people not wanting to open the radio.

Winding some turns on the actual loopstick is what would be happening if
that radio had an external antenna connection.

And it would be the same if a radio didn't have a loopstick but just a
tuning coil, there'd be a few turns of wire as a primary to couple the
antenna to the tuned circuit.

Michael

External ferrite bar for 2-6 MHz?
 

On Feb 26, 9:10*pm, Michael Black wrote:
On Fri, 26 Feb 2010, Kevin Alfred Strom wrote:
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.

And that's all that's necessary.

The winding of wire around the radio, the external coupling loop, those
are all constructs to deal with people not wanting to open the radio.

Well, that's the whole point! I did not want to open the radio up and
mess with the ferrite already wrapped with the most fragile-looking
wire imaginable.

Winding some turns on the actual loopstick is what would be happening if
that radio had an external antenna connection.

And it would be the same if a radio didn't have a loopstick but just a
tuning coil, there'd be a few turns of wire as a primary to couple the
antenna to the tuned circuit.

Understood.

* * Michael

I actually tried wrapping a wire around the radio per Kevin's
suggestion. What I found was that a single loose wrap of wire, with
about 10 feet going across the room and the other end attached to a
ground, was enough to dramatically increase the coupled signal. 4.8 -
6.2 MHz became significantly louder. 1/2 additional wrap was enough
to begin to overload the band with intermod products from 3 or 4
nearby 50 kW MW blowtorches. Two full wraps obliviated any resonant
signals. My wires on the roof are clearly severe overkill, possibly
in the literal sense. I did not try my PAR high-pass MW attenuation
filter inline; it might have had some effect.

My guess is that this inexpensive old single-conversion portable is
probably too sensitive and too loose on its front end to worry about
it much more. If I did the external ferrite rod, it would likely
perform best positioned linearly with the internal ferrite rod rather
than broadside, although the radio is so sensitive that broadside
might work OK. I think it might have to be tuned with a slug or a VC,
just to allow some selectivity to remain.

Bruce