I have gotten some large 125mu binocular cores from the dumpster here
at work. If they are a good choice for your balun then I will make a
portion of them available to people here on this board for shipping
cost. The holes are about 1/4" with a LOT of ferrite around it.
Should only need I think 1:3 of small wire for a nice unit.

If somebody who knows more than me would like to make comment on a
good design then please do.

regards,
NEO

When I think of binoculars,I think of the kind with glass lenses,of
which I own a few of them.
cuhulin

On Feb 17, 12:56 pm, wrote:
When I think of binoculars,I think of the kind with glass lenses,of
which I own a few of them.
cuhulin

The binocular cores I speak of have two holes that you pass the wires
through. They usually have a lof of ferrite material that you wind
around so you get a lot of inductance per turn. That is nice for
making wideband transformers.

Yes, the binoculars you speak of are very nice. I live across the
street from a large apartment complex. If you ever get by this way
please bring two pairs of binoculars and we will check out the people
in the windows. Dogs are welcome here so no prob. Do you own any
Kalideoscopes? They are fun too.

regards,
NEO

I think www.amazing1.com and some other stores sell some laser
light listening devices.I think the way they work (or suppose to work)
is the laser light picks up vibrations from sounds behind the windows
and converts the vibrations into sounds you can hear with head phones
connected to the laser light listening device.I have never tried out one
of those rigs though.Do a search for, Laser Light Listening Devices

I think I have a fancy kalideoscope around here somewhere that I bought
about thirty years ago.I used to play with those gadgets when I was a
kid.
cuhulin

N9NEO wrote:

I have gotten some large 125mu binocular cores from the dumpster here
at work. If they are a good choice for your balun then I will make a
portion of them available to people here on this board for shipping
cost. The holes are about 1/4" with a LOT of ferrite around it.
Should only need I think 1:3 of small wire for a nice unit.

If somebody who knows more than me would like to make comment on a
good design then please do.

regards,
NEO

Do know anything about the ferrite material of these cores or what they
were used for?

On Feb 18, 8:47 pm, HFguy wrote:
N9NEO wrote:
I have gotten some large 125mu binocular cores from the dumpster here
at work. If they are a good choice for your balun then I will make a
portion of them available to people here on this board for shipping
cost. The holes are about 1/4" with a LOT of ferrite around it.
Should only need I think 1:3 of small wire for a nice unit.

If somebody who knows more than me would like to make comment on a
good design then please do.

regards,
NEO

Do know anything about the ferrite material of these cores or what they
were used for?

Yes, Mu is 125 and they were used in a commercial 250w transmitter
final.

73
NEO

On Feb 19, 12:49 pm, "N9NEO" wrote:
On Feb 18, 8:47 pm, HFguy wrote:

N9NEO wrote:
I have gotten some large 125mu binocular cores from the dumpster here
at work. If they are a good choice for your balun then I will make a
portion of them available to people here on this board for shipping
cost. The holes are about 1/4" with a LOT of ferrite around it.
Should only need I think 1:3 of small wire for a nice unit.

If somebody who knows more than me would like to make comment on a
good design then please do.

regards,
NEO

Do know anything about the ferrite material of these cores or what they
were used for?

Yes, Mu is 125 and they were used in a commercial HF 250w transmitter
final.

73
NEO

The cores are 1.2" x 1.2" x0.6" Holes are 0.25"