Static 9:1 balun
Joe Strain
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=-" <j...@ask.me.com> wrote in message
news:Xns93AAE91A2E3D...@216.168.3.44...
> 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
>
Dave
If your co-ax is well grounded you don't need the capacitor.
On Tue, 01 Jul 2003 02:56:06 -0000, "-=jd=-" <j...@ask.me.com> wrote:
craigm
Joe Strain wrote:
> 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
>
10k is a good value for the resistor.
In this application the resistor is in parallel with the bulb. Its
purpose is to bleed off any static that generates. In this case, lower
is better, but you want to keep the value well above ( 10X ) the
impedance of whatever is connected.
When there is a nearby strike, more voltage will be generated on the
antenna. When the voltage exceeds 90 volts, the lamp fires. It
discharges the antenna until the voltages drops below 65 volts. After
that, the resistor bleeds off the rest.
When using the lamp as a pilot light, the resistor is in series with the
bulb. This is done to limit current. Too much current and the bulb's
life is shortened.
As another poster mentioned, a balun tends to put everything at ground
potential anyway.
None of this is sufficient to handle a direct strike. Also a
sufficiently large nearby strike could still cause damage to a radio.
Enjoy
Craig
N8KDV
-=jd=- wrote:
> On 01 Jul 2003, craigm <camenRE...@charter.net> wrote:
>
> > Joe Strain wrote:
> >
> >> ...snip...
> I was hoping someone would verify that the resistor is parallel
> with the bulb - I had second thoughts after reading Joe's post.
> As for lightning protection, I'm thinking that if a lightning
> strike hits that close or directly, I'm probably screwed
> regardless. I'll opt for disconnecting the ant. when not in use.
>
> I have now strung the whole affair up. As previously stated,
> except that from the 14' post at the house to only about 8' up
> the the tree for now (I'll need a sling-shot to hit the 30'
> mark). Even so, the difference is remarkable!
>
> The drop-off in ambient noise is remarkable. I tried the three
> different antennas (dx mode) while tuned to 10mhz and found
> that:
>
> Coax-Fed Random Wire - clear as a bell and signal meter was
> maxed on 5 and stayed there (scale 1 - 5). I'm presuming the
> coax feed along with the 30' rope extending the antenna way from
> the house were the significant factors as I disconnected the
> static-filter/balun unit and could not tell a bit of difference
> (with my uncalibrated ear-ball). Seemed to be similar results on
> other freqs.
>
> Built-In Aerial - The stations was in and out, I could pick up a
> beep occasionally over the noise. Signal meter fluctuated from 1
> to 3, but I think that was more the noise level.
>
> Wind-up Ant: Worse than the Aerial. Nothing but noise. Signal
> meter fluctuated from 2 to 4.
>
> Either that particular freq did not present the circumstances
> where the static-filter/balun would be worthwhile -or- the
> static-filter/balun really doesn't do much for me regarding
> reception improvement. In any event, it doesn't seem to have an
> effect either way, so no harm done that I can tell. That, and
> winding it salvaged an otherwise rainy afternoon...
>
> So I'm wondering if a balun is a waste of time on a random wire
> for SWL only. At least, in the case of Joe Listener just
> sticking a length of wire up - not in the case of big beverages
> or some other "formal" (lack of a better word) antenna rig...
Are you sure you have the balun/matching transformer wired and connected
properly?
Mark S. Holden
>
> On 01 Jul 2003, craigm <camenRE...@charter.net> wrote:
>
> > Joe Strain wrote:
> >
> >> ...snip...
> I have now strung the whole affair up. As previously stated,
> except that from the 14' post at the house to only about 8' up
> the the tree for now (I'll need a sling-shot to hit the 30'
> mark). Even so, the difference is remarkable!
>
I used to use a sling shot - I've found it's easier to launch my antennas by tossing a 5 ounce lead fishing weight with some fishing line over a branch, and then pulling up my rope. It's even easier if you know someone who used to be a pitcher. "The
strike zone is that fork about 35 feet up."
<snip>
> So I'm wondering if a balun is a waste of time on a random wire
> for SWL only. At least, in the case of Joe Listener just
> sticking a length of wire up - not in the case of big beverages
> or some other "formal" (lack of a better word) antenna rig...
>
> JD
>
Baluns do improve impedance matching, but just having the ferrite they're normally wound on close to the coax will help reduce RFI too.
With an outdoor antenna, most of the RFI you're picking up is probably finding it's way to the antenna on the shield of the coax. The ferrite acts like a choke to help filter it out.
Regards,
Mark
N8KDV
-=jd=- wrote:
> On 02 Jul 2003, N8KDV <n8...@nospam.iserv.net> sneezed on the
> keyboard, resulting in:
> >
> >> -=jd=- wrote:
> >>
> >> ...snip...
> >> So I'm wondering if a balun is a waste of time on a random
> >> wire for SWL only. At least, in the case of Joe Listener
> >> just sticking a length of wire up - not in the case of big
> >> beverages or some other "formal" (lack of a better word)
> >> antenna rig...
> >
> > Are you sure you have the balun/matching transformer wired
> > and connected properly?
>
> I'm fairly confident that I do, but I can't say it is exact. I'd
> like to examine a known good one before I would hazard claiming
> I got it 100% right.
>
> I know I have the leads absolutely correct, as per the design in
> (http://www.hard-core-dx.com/nordicdx/antenna/feed/9_
> 1balun.html).
>
> The only question is in the wraps. They are done neatly and do
> not overlap. It took me a few tries to get the wraps on like I
> wanted - evenly spaced, no overlap, snug against the choke...
> However, depending on how you count the wraps, I have either
> (30):(10) wraps -or- (30-1/2):(10-1/2) wraps. I have no idea if
> that would make a difference and would defer to the groups
> advice.
>
> 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.
Ah... therein may lie the problem... as much as people have argued with
me in the past about this, I can only say that all ferrite cores are not
created equal...
>
>
> I do appreciate the feedback!
>
> Thanks,
> JD
N8KDV
N8KDV wrote:
Not sure whether you've read this article or not:
http://members.aol.com/DXerCapeCod/z_transformers.pdf
N8KDV
Here's another article comparing the MLB to the matching transformers
I used to build:
http://www.iserv.net/~n8kdv/xfmr.htm
dxlover
> Ah... therein may lie the problem... as much as people have argued with
> me in the past about this, I can only say that all ferrite cores are not
> created equal...
I must have missed those threads on that Steve, can you expound a little on
that? Do you feel the rat shacks cores are suffice?
--
~*~*~Monitoring the Spectrum~*~*~
***GO BEARCATS***
~~~Hammarlund129X/140X~~~
**Heathkit Q MUltiplier**
<><><><><>GE P-780<><><><><><><><
N8KDV
dxlover wrote:
> >
> > Ah... therein may lie the problem... as much as people have argued with
> > me in the past about this, I can only say that all ferrite cores are not
> > created equal...
>
> I must have missed those threads on that Steve, can you expound a little on
> that? Do you feel the rat shacks cores are suffice?
I have no idea what material the cores that Radio Shack sells are made of. They
are probably ferrite, but there is a difference in the 'mix' that is used.
Robert F Wieland
your wire and the project box containing the balun (autotransformer). I
would recommend moving the box to the end of the wire, and using the run
of coax going back to the receiver to "come down" from the box to the
ground. This would, I admit, give you a problem of how to make the ground
connection to the coax shield at the antenna end; you could use a
grounding block, which requires your coax run to have connectors at this
point, or you need to do some "surgery" to the coax to take off the outer
covering without cutting the shield (for this, go to a sewing shop and
look at the tool called a "seam ripper", and you may see how to use it to
"uncover" coax shield).
This is a slightly funny antenna, the wire together with the exterior of
the coax shield, creates a grounded Inverted-L that has its feedpoint not
at the ground stake, but at the balun.
I've been playing with the idea of winding a coil with the coax at the
ground stake (back-of-envelope calculations say 200 uH) which makes this
antenna self-decoupling: at high frequencies, the high reactance
disconnects the "bottom" of the antenna from the ground, and it's a
bent dipole; at low frequencies, the low reactance makes it an Inverted-L.
One antenna for LW to 30MHz?
You asked for ideas...
--
R F Wieland Newark, DE 19711-5323 USA 39.68N 75.74W
Icom R75 Heathkit GR-81 Inverted-L in the attic
Reply to wieland at me dot udel dot edu
N8KDV
Robert F Wieland wrote:
> If I understand you correctly, you propose to put coax between the end of
> your wire and the project box containing the balun (autotransformer). I
> would recommend moving the box to the end of the wire, and using the run
> of coax going back to the receiver to "come down" from the box to the
> ground.
Yes. And it depends on how the transformer is wound/connected. The ones I use
here use a separate ground from the feedpoint. (So, what I'm using are two
ground rods, feedpoint, from the transformer, and at the shack from the
receiver.) The winding off the toroid from the wire itself is totally separate
from the winding that goes to the coax.
Now, it is possible to connect the grounds at the transformer (ala MLB) and
avoid the ground at the feedpoint. I've used/made them both ways, but I prefer
the two ground method.
> This would, I admit, give you a problem of how to make the ground
> connection to the coax shield at the antenna end;
I run the coax near the end into a Transi-trap... ground that, and after that
the only ground is from the receiver.
Telamon
"-=jd=-" <j...@ask.me.com> 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.
--
Telamon
Ventura, California
N8KDV
-=jd=- wrote:
> On 03 Jul 2003, Telamon
> 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.
Steve
Holland, MI
Drake R7, R8 and R8B
craigm
"N8KDV" <n8...@nospam.iserv.net> wrote in message
news:3F085E45...@nospam.iserv.net...
>
> 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
N8KDV
craigm wrote:
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!
N8KDV
-=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
N8KDV
-=jd=- wrote:
> >On 07 Jul 2003, N8KDV <n8...@nospam.iserv.net> 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
N8KDV
-=jd=- wrote:
> >On 07 Jul 2003, N8KDV <n8...@nospam.iserv.net> 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.
N8KDV
-=jd=- wrote:
> 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
RHF
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" <jstr...@cfl.rr.com>
= = = wrote in message news:<LulMa.177650$cm4.4...@twister.tampabay.rr.com>...
RHF
? 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.
~ RHF
.
.
= = = N8KDV <n8...@nospam.iserv.net>
= = = wrote in message news:<3F086919...@nospam.iserv.net>...
N8KDV
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.
Dale Parfitt
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
N8KDV
Dale Parfitt wrote:
Some very good points Dale.
RHF
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 <par...@gte.net>
= = = wrote in message news:<3F169C28...@gte.net>...
N8KDV
RHF wrote:
> 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
Didn't they put this same sort of setup in one of the NRD's (JRC) of yore, only to
discover it caused intermod and had to be removed.?
Dale Parfitt
N8KDV wrote:
> RHF wrote:
>
> > 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.
>
They don't have to be driven into conduction just into the square law region.
>
>
> Didn't they put this same sort of setup in one of the NRD's (JRC) of yore, only to
> discover it caused intermod and had to be removed.?
>
Some years back, an amateur mfg had varicaps tuning a front end filter- IP3 characteristic
was horrible. The next generation got rid of the idea.
Dale W4OP
Telamon
N8KDV <n8...@nospam.iserv.net> wrote:
He is more than right. Diodes are used as broadband white noise sources
in test equipment.
--
Telamon
Ventura, California