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

Aren't all parts of those 9:1 baluns at DC ground already?

If your co-ax is well grounded you don't need the capacitor.

On Tue, 01 Jul 2003 02:56:06 -0000, "-=jd=-" wrote:

core-dx.com/nordicdx/antenna/feed/9_1balun.htm

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. 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

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

-=jd=- wrote:

On 01 Jul 2003, craigm wrote:

Joe Strain wrote:

...snip...
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

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?



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

-=jd=- wrote:

On 02 Jul 2003, N8KDV 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

-=jd=- wrote:

On 01 Jul 2003, craigm wrote:

Joe Strain wrote:

...snip...
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 wrote:

-=jd=- wrote:

On 02 Jul 2003, N8KDV 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...

Not sure whether you've read this article or not:

http://members.aol.com/DXerCapeCod/z_transformers.pdf






I do appreciate the feedback!

Thanks,
JD

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

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.

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