craigm wrote:

"N8KDV" wrote in message
...

Magnetics has nothing to do with it. It's the composition/material of
the core. Have you taken the time to read the material I posted before?
If you haven't, I suggest you do so.

Steve
Holland, MI

Drake R7, R8 and R8B



The composition/material of the core establish its magnetic properties.

Try this reference.

http://www.amidon-inductive.com/aai_ferritecores.htm

craigm

Been there, read it, have had their catalog for years! Who cares about the
magnetics? What we care about is indeed the composition/material of the core.

Read the specs, embrace them as gospel. All cores are not created equal!

Steve
Holland, MI

Drake R7, R8 and R8B

-=jd=- wrote:

On 06 Jul 2003, N8KDV wrote:



-=jd=- wrote:

On 03 Jul 2003, Telamon
wrote:

In article
,
"-=jd=-" wrote:

Err... I also don't know if this makes any difference
either, but I used the square ferrite choke from Radio
Shack, as I could not find a round one anywhere
locally.

This could be a real problem because it is in two
pieces. A small gap (you have two) greatly reduces the
inductance of the core. Use some tape for now to make
sure the two halves are pulled tightly together for now
while you order a toroid for a permanent fix. The
composition of the core material should be OK.


Out of curiosity, and because I can't find anything on the
net that speaks directly to it, does anyone know if it's
the composition/material of the core that's important, or
it's magnetic strength, or some combination of both?

jd

Magnetics has nothing to do with it. It's the
composition/material of the core. Have you taken the time
to read the material I posted before? If you haven't, I
suggest you do so.

Well, the confusion I have arises when I see insulated wire
wound around a core...

Well, it had better be insulated to some extent...



I'll take another look at the info you pointed me to.

jd

-=jd=- wrote:

On 07 Jul 2003, N8KDV wrote:

...snipped...

-=jd=- wrote:

Well, the confusion I have arises when I see insulated wire
wound around a core...

Well, it had better be insulated to some extent...



I'll take another look at the info you pointed me to.

jd


So far, looking over the .pdf on xformer construction, and
looking at other sources, it seems to be the magnetism that is
the key. In the .pdf (Fabricating Impedance Transformers
for Receiving Antennas by John Bryant - May 2001)advises in it's
last sentence: "May the forces (magnetic) be with you!"

As to the insulation, one use (not the only use) for it is to
maintain the spacing of the wires. One source stressed that a
couple times.

In general, the info tends to indicate that the winding's
magnetic field interacts with the core's magnetic field in some
manner to acheive the desired result. I can't find any mention
as to the composition of the core having more of an effect...
I'm continuing to look, though.

If anything, you've peaked my curiosity about it enough to
occupy my evenings for a bit.

Well, have fun. It's actually pretty simple.



JD

-=jd=- wrote:

On 07 Jul 2003, N8KDV wrote:

...snipped...

-=jd=- wrote:

Well, the confusion I have arises when I see insulated wire
wound around a core...

Well, it had better be insulated to some extent...



I'll take another look at the info you pointed me to.

jd


So far, looking over the .pdf on xformer construction, and
looking at other sources, it seems to be the magnetism that is
the key. In the .pdf (Fabricating Impedance Transformers
for Receiving Antennas by John Bryant - May 2001)advises in it's
last sentence: "May the forces (magnetic) be with you!"

As to the insulation, one use (not the only use) for it is to
maintain the spacing of the wires. One source stressed that a
couple times.

In general, the info tends to indicate that the winding's
magnetic field interacts with the core's magnetic field in some
manner to acheive the desired result. I can't find any mention
as to the composition of the core having more of an effect...
I'm continuing to look, though.

If anything, you've peaked my curiosity about it enough to
occupy my evenings for a bit.

JD

If you read the article carefully you may discern that the cores
composition is indeed critical. It's indeed right there in front of your
eyes.

As I stated at the start of this discourse, I knew that there may indeed
be some argument or perhaps reluctance. Been through it before...

Meanwhile... I'll be enjoying the weak signal DX.

I wish you the best of luck.

I just give up!

I'll leave the rest of you to your own devices, schemes, etc.

-=jd=- wrote:

On 07 Jul 2003, N8KDV wrote:



-=jd=- wrote:

On 07 Jul 2003, N8KDV wrote:

...snipped...

-=jd=- wrote:

Well, the confusion I have arises when I see insulated
wire wound around a core...

Well, it had better be insulated to some extent...



I'll take another look at the info you pointed me to.

jd


So far, looking over the .pdf on xformer construction, and
looking at other sources, it seems to be the magnetism
that is the key. In the .pdf (Fabricating Impedance
Transformers for Receiving Antennas by John Bryant - May
2001)advises in it's last sentence: "May the forces
(magnetic) be with you!"

As to the insulation, one use (not the only use) for it is
to maintain the spacing of the wires. One source stressed
that a couple times.

In general, the info tends to indicate that the winding's
magnetic field interacts with the core's magnetic field in
some manner to acheive the desired result. I can't find
any mention as to the composition of the core having more
of an effect... I'm continuing to look, though.

If anything, you've peaked my curiosity about it enough to
occupy my evenings for a bit.

JD

If you read the article carefully you may discern that the
cores composition is indeed critical. It's indeed right
there in front of your eyes.

As I stated at the start of this discourse, I knew that
there may indeed be some argument or perhaps reluctance.
Been through it before...

Meanwhile... I'll be enjoying the weak signal DX.

I wish you the best of luck.

I just give up!

I'll leave the rest of you to your own devices, schemes,
etc.

I appreciate your voluntary replies. I apologize if, in some
way, you felt obligated to "teach". I can assure you that was
not my intent. I was just seeking opinions.

I understand, I just give up.



jd

JS,

I have used the NE-2 Neon Bulb and 10K Ohm Risistor with my portable
radio Antenna "GIZMOE" Connector Box to protect the external antenna
inputs of several radios.

I have also used a double pairing of Forward & Reverse Diodes to act
as a low voltage shunts along with the NE-2 Neon Bulb as the Higher
Voltage Shunt and the 10K Ohm Resistor for Static Bleed-Off.

G = Ground
* = Space
| = Bus Wire
- = Connector Wire
^ = Pot's Wiper

G**********A = External Antenna
|----o)----| = NE-2 Neon Bulb or Gas Discharge Tube
|**********|
|--|--|--| = Forward Diodes
|**********|
|--|--|--| = Reverse Diodes
|**********|
|--/\/\/\--| = 10K Ohm Resistor / Potentiometer
|****^****** = Pot's Center Wiper
|****|******
|****------|
G**********R = Radio's External Antenna Input


The INPUT Side of the Gizmoe has an SO-237 Connector plus an Antenna
and Ground Terminals.

The OUTPUT Side of the Gizmoe has a 1/8" Stereo Plug with the
Tip=Antenna and the Rear Barrel = Ground (Center Section is not used)
plus Antenna and Ground Terminals.

NOTE: Using a 10K Ohm Potentiometer with the Center Arm "Wiper" as an
output to the Radio's Antenna Input allows for the adjustment of the
external antennas signal level to reduce overloading the portable
radios RF (Front End) Input. Functions as an External RF Gain Control
for the radio.

FWIW: Using a Gas Discharge Tube {GDT} instead of an NE-2 Neon Bulb
is recommended.
- - - The GDT's are reported to handle more current and voltage.


jm2cw ~ RHF
..
..
= = = "Joe Strain"
= = = wrote in message .com...
I am doing the same thing myself, but let's think about the anti-static
feature which uses a Ne-2 bulb a 10K resistor and IIRC a .01 capacitor

The NE-2 is a NEON tube...They don't conduct, they FIRE like a Thyratron,
they are gas discharge tubes...like a stone age Zener diode. The NE-2 (
when I used them in strobe-light power supplies, fired at 65 volts and until
it reached 65 volts, it did NOTHING.

Reading recent references I see it is listed as a 105-125 V
device...perhaps that's for optimum "brightness"...I just know it FIRES at
65 ac volts. at any rate the 10K resistor is a good order of magnitude too
low in my opinion...The reference ( a xeroxed page from a catalog listing
all the neon tubes characteristics) says the bulb needs a 200K resistor for
a 65V AC firing voltage (RF is AC) or 90V DC firing voltage.

Can we have some practical experience here from the "listeners" about
whether the resistors should be 10K or 200 K ?

Yodar


"-=jd=-" wrote in message
.. .
I'm a newcomer to SWL and I've been perusing the boards and the various
sites. Lots of interesting info to be found all over - perhaps too much
info. I'm quite possibly a good example of the adage that a little
knowledge can sometimes be a dangerous thing.

So, I'm thinking of the following to reduce noise while listening inside
the house (with a Grundig YB400PE):

The plan is to string 100-feet of #14 wire from a 14-foot post next to
the house to a tree (about 130-feet away and 30-feet up) with about 30-
feet +/- of rope on the post end of the wire. I'll connect coax from the
end of the wire to a project box; from the project box to a ground-rod;
from the ground-rod to the receiver.

About the project box:
It was raining and I was bored. I took the anti-static design from the
AMANDX site (www.angelfire.com/mb/amandx/static.html)

And the 9:1 balun from the hard-core-dx/nordicdx site (http://www.hard-
core-dx.com/nordicdx/antenna/feed/9_1balun.html)

And I've combined both designs into one box. The way I did it was to
connect the capacitor from the static filter to the antenna side of the
balun (hope that makes sense). Oh, it looks like hell, but I'm thinking
it might actually work ok.

I'm hoping to string it all up as soon as Tropical Storm "Bill" blows
through and see if there's any difference from the built-in and wind-up
antennas. Given that I am (admittedly) a totally green newbie and have
*no* clue about the theory behind the random wire antennas, the anti-
static filter or baluns, I'm wondering if anyone may have any advice they
may like to offer regarding what I have planed, other than gales of
derisive laughter...

JD
--
"Who are you going to believe, me or your lyin' eyes?" -Groucho Marx

RHF wrote:

Steve & Craig,

? QUESTION: Are Not the Composition/Material of the Core and the
Core's Magnetic Properties "Intertwined" ?

- The Magnetics are a 'result' of the Cores Composition/Materials.

- Cores Composition/Materials are 'selected' for their Magnetics.

OK. That's just fine. But you still need to know the characteristics of the core to
wind the transformer.



~ RHF
.
.
= = = N8KDV
= = = wrote in message ...
craigm wrote:

"N8KDV" wrote in message
...

Magnetics has nothing to do with it. It's the composition/material of
the core. Have you taken the time to read the material I posted before?
If you haven't, I suggest you do so.

Steve
Holland, MI

Drake R7, R8 and R8B



The composition/material of the core establish its magnetic properties.

Try this reference.

http://www.amidon-inductive.com/aai_ferritecores.htm

craigm

Been there, read it, have had their catalog for years! Who cares about the
magnetics? What we care about is indeed the composition/material of the core.

Read the specs, embrace them as gospel. All cores are not created equal!

Steve
Holland, MI

Drake R7, R8 and R8B

RHF wrote:

JS,

I have used the NE-2 Neon Bulb and 10K Ohm Risistor with my portable
radio Antenna "GIZMOE" Connector Box to protect the external antenna
inputs of several radios.

I have also used a double pairing of Forward & Reverse Diodes to act
as a low voltage shunts along with the NE-2 Neon Bulb as the Higher
Voltage Shunt and the 10K Ohm Resistor for Static Bleed-Off.


Neon tubes "fire" at around 80-110V. Can your front end take this? Older tube rigs
can, not sure I would bet on a FET front end.
A pair of diodes right on the input can be disastrous. They are a nonlinear device,
easily driven into generating all sorts of mixing products- as they are right at the
antenna, everything from local AM, FM and TV will be seen by the diodes.

Dale W4OP

Dale Parfitt wrote:

RHF wrote:

JS,

I have used the NE-2 Neon Bulb and 10K Ohm Risistor with my portable
radio Antenna "GIZMOE" Connector Box to protect the external antenna
inputs of several radios.

I have also used a double pairing of Forward & Reverse Diodes to act
as a low voltage shunts along with the NE-2 Neon Bulb as the Higher
Voltage Shunt and the 10K Ohm Resistor for Static Bleed-Off.


Neon tubes "fire" at around 80-110V. Can your front end take this? Older tube rigs
can, not sure I would bet on a FET front end.
A pair of diodes right on the input can be disastrous. They are a nonlinear device,
easily driven into generating all sorts of mixing products- as they are right at the
antenna, everything from local AM, FM and TV will be seen by the diodes.

Dale W4OP

Some very good points Dale.

DP,

1. When the radio is not being used the POT is set to Zero and the
Receiver's Antenna Input is Shorted-Out and Grounded.

2. This is a 'set' of both Forward and Reverse Diodes Dual [Doubled]

--|--|--

--|--|--

If you have enough wide band RF signal levels to make these dual
diodes work then with a modern solid state radio most likely you have
major front-end overload in the radio.


~ RHF
..
..
= = = Dale Parfitt
= = = wrote in message ...
RHF wrote:

JS,

I have used the NE-2 Neon Bulb and 10K Ohm Risistor with my portable
radio Antenna "GIZMOE" Connector Box to protect the external antenna
inputs of several radios.

I have also used a double pairing of Forward & Reverse Diodes to act
as a low voltage shunts along with the NE-2 Neon Bulb as the Higher
Voltage Shunt and the 10K Ohm Resistor for Static Bleed-Off.


Neon tubes "fire" at around 80-110V. Can your front end take this? Older tube rigs
can, not sure I would bet on a FET front end.
A pair of diodes right on the input can be disastrous. They are a nonlinear device,
easily driven into generating all sorts of mixing products- as they are right at the
antenna, everything from local AM, FM and TV will be seen by the diodes.

Dale W4OP