Need suggestions to reduce signal pick up of coax cable.

[amdx]

I started an AM receive antenna installation by laying out 200ft of RG6
coax. It's good coax with braid plus foil shield.
The coax is on the ground, I shorted the end and connected the other
end to my radio, there are no ground connections.
The coax has 3 to 6 S units on my local radio stations.
I want my coax to pick up as little signal as possible, because I want
to install directional antenna on it.

Next, I tried grounding the far end to a 5ft copper rod,
this increased signal strength.

Then I grounded the shield just before it enter the house,
this increased signal strength.

Removing the far end ground and having just the ground near the radio
didn't help.

I tried 3 different Chokes on the Coax at the radio, one monster choke
is a very large potcore that I wound 15 turns of coax on, it has 25kohms
of reactance at 1MHz.
The chokes didn't help.

I wound a 1:1 Isolation transformer installed at the radio.
That didn't help.

I could invest in some Quad shield cable, but nope.
I already have over 1000ft of RG6.

The quietest so far is just the coax, no grounds.
The chokes and transformer didn't seem to hurt, but they didn't help either.

I also changed the short at the far end to a 75 ohm resistor.
That didn't help.

Anyone have recommendations on how to quiet the coax?

Mikek

[69883925...@nospam.org]

On a sunny day (Sat, 9 Jun 2018 07:31:35 -0500) it happened amdx
<noj...@knology.net> wrote in <pfghbc$8bi$1...@dont-email.me>:

First thing:
What sort of noise do you get with that co-axe?.
If it is the usual MW RF impulse noise, better find the source.
put a second antenna near the noise source, and use one of those noise subtracter circuits:
http://www.vk5tm.com/homebrew/noisecancel/noisecancel.php

2) Is the grounding of the coax at the receiver, so the receiver's input circuit, correct?
This is easy to check, short the co-axe at the receiver side, and the noise should disappear,
if not then the receiver's input circuit is shit.
Best circuit is likely just a single turn and then an LC, note the galvanic isolation

--------- FET gate
===-- | |
| | |( |/ Ctune
| )|( ===
|___| |( /|
|______|
|
///

3) In any case it is better to have a preamplifier at the antenna side, and a less sensitive RF input stage in the receiver.

[bill....@ieee.org]

Semi-rigid coax - where the outer conductor is thin tube of solid copper - is probably the nicest, but 200 feet wouldn't be cheap

http://www.farnell.com/datasheets/1700823.pdf

covers RG402. 200feet is 61 metres, and for that much it's $A11.84 per metre in Australia.

Solder-on connectors aren't cheap either.

It's going to be cheaper in the US - Newark will sell you a 50 metre spool for $US184.14

--
Bill Sloman, Sydney

[gnuarm.del...@gmail.com]

Don't know, but just a thought, try installing a common mode choke. At FM frequencies this can be a few turns of the coax on a 2 liter coke bottle. Normally this deals with issues created by a balanced antenna on an unbalanced line, but really it has to do with currents on the outside of the coax. The fact that grounding your shield at the remote end increased the noise makes me think this could be your problem.

Rick C.

[John S]

Does the signal go away if you disconnect the center conductor at the radio?

[amdx]

I had to check, I did not use the word noise, I'm receiving radio
signals on my coax.
How do I quiet it?

> If it is the usual MW RF impulse noise, better find the source.

When I installed my active mini whip I had terrible noise, I have
already conquered electrical impulse noise.
Mostly outdoor lighting with sensors.
Mikek

[amdx]

I addressed that here,

"I tried 3 different Chokes on the Coax at the radio, one monster choke
is a very large potcore that I wound 15 turns of coax on, it has 25kohms
of reactance at 1MHz.
The chokes didn't help."

They were all CMCs.

[amdx]

I'll try that later today.
Mikek

[Johnny B Good]

JOOI, did you try touching the tip (or screen - it shouldn't matter
which in this case) of the co-axial plug to the screen/ground of the
receiver’s co-axial aerial socket? The interference could simply be due
to ground currents in the receiver's input circuit leaking into its input
filter.

If you just connect that co-ax to the centre pin on the aerial socket as
an end fed long wire aerial, you're likely going to see S9 plus 30dB or
higher signals on the Medium Wave band (I've assumed you mean the MW
broadcast band with your AM reference). Trying to attenuate a 30dB over S9
signal down to the S1 level, assuming 6dB per S point, corresponds to a
total attenuation factor of 78dB. That level of attenuation is tricky
enough to achieve in the best of circumstance and no mean feat at that!

Considering your project (200 feet of co-ax *and* a directional aerial
for the MW band), I guess you must be well clear of any conurbations and
out in open country. Even though you might not be so troubled by QRM as
most of us unfortunates usually are, QRN is likely to be the limiting
factor in this case. That S6 level of unwanted leakage from local MW
broadcast stations is likely to be drowned out by the QRN from a decent
MW antenna array anyway. You may be worrying about nothing if those
interfering signals from such an antenna array are going to appear as S9
plus 30dB or higher anyway.

I suspect the problem is less to do with a deficiency of the co-ax and
more to do with a deficiency of receiver's input screening, hence my
suggestion above.

--
Johnny B Good

[mpm]

On Saturday, June 9, 2018 at 8:31:44 AM UTC-4, amdx wrote:

> Anyone have recommendations on how to quiet the coax?
>

How much would 200' of aluminum foil cost you?
You could just foil-wrap the whole run. And depending on the width of the foil, you could probably get 3x or 4x the length by cutting the foil in strips first.

Would be messy to install.

Also, are you concerned about lightning damage? (i.e., a lightning strike being conducted into your house/receiver? Something to consider?

[amdx]

JohhnyBgood, could you repost, on both of my computers your post is empty.
Mikek

[jurb...@gmail.com]

I haven't read the replies yet but the first thing that comes to mind is to find or wind baluns and use 2 lines of coax cut to the same length. Like a home brew LVDS. Of course the shields are connected directly and you might even want to strip it to the shield in a few places in the run and clamp them together - electrically of course but the right clamp is probably what you'll need. This will further reduce pickup, making more sure that it is common mode even if it comes to ground gradients.

I think the way you described what you're getting with the current setup is the shield is picking up the signal inductively. Even if you leave one end open it is still RF so that doesn't necessarily mean shit.

Now I will read the rest and either find out that I am an asshole or (EEK !) that I am right. You did say you had a bunch of RG-6, and I am a firm proponent of using what you got.

[upsid...@downunder.com]

On Sat, 9 Jun 2018 07:31:35 -0500, amdx <noj...@knology.net> wrote:

>I started an AM receive antenna installation by laying out 200ft of RG6
>coax. It's good coax with braid plus foil shield.
> The coax is on the ground, I shorted the end and connected the other
>end to my radio, there are no ground connections.

Is the receiver mains powered and especially double insulated ? If
there are just an antenna connect tion but no ground connection, the
antenna grounding happens through the signal ground through the power
supply bridge rectifier and mains transformer capacitance to mains
neutral. This can cause mains buzz (and possibly intermodulation
products), if the rectifier diodes are not bypassed with small
capacitors.

What is the radio input stage like ? Is it part of a ferrite rod
antenna or perhaps a source follower intended for a whip antenna ? Or
perhaps a proper 50/75 ohm input stage with a pi-section as in some
car radios ?

While impedance matching is not critical for reception especially on
MW band, but proper impedance matching is critical for proper
transmission line operation (such as interference intrusion) of the
coax cable.

Make sure that the receiver shows about 50 ohm termination resistance
to the cable. If the receiver input impedance is much higher, you may
need a step-up isolation transformer or a 50-100 ohm resistor across
receiver input, with some loss of wanted distant signal.

[amdx]

If I understand--- I have taken the coax loose and connected just the
shield to the shield connection of the radio.
No signal.
Connecting the coax shield to the center pin of the radio does give
plenty of signal, but I think that's not a problem.

> If you just connect that co-ax to the centre pin on the aerial socket as
> an end fed long wire aerial, you're likely going to see S9 plus 30dB or
> higher signals on the Medium Wave band (I've assumed you mean the MW
> broadcast band with your AM reference).

Naw, highest signal is about an S 9, plus a few db.

Trying to attenuate a 30dB over S9
> signal down to the S1 level, assuming 6dB per S point, corresponds to a
> total attenuation factor of 78dB. That level of attenuation is tricky
> enough to achieve in the best of circumstance and no mean feat at that!
>
> Considering your project (200 feet of co-ax *and* a directional aerial
> for the MW band),
I guess you must be well clear of any conurbations and
> out in open country. Even though you might not be so troubled by QRM as
> most of us unfortunates usually are, QRN is likely to be the limiting
> factor in this case. That S6 level of unwanted leakage from local MW
> broadcast stations is likely to be drowned out by the QRN from a decent
> MW antenna array anyway.

Not seeing nearly as much noise as you.
I just put two very large CMCs on the power cord of the radio, An Icom
71A btw. This did reduce the signal pick up.
So, now with the power cord CMC and a short at the far end of the coax,
I have 5 S units on 590kHz, but 1260kHz and 1430kHz only have 0.5 S
units, that is a huge reduction.
This leads me to think I need to run my radio from a battery.

590kHz has been the highest signal with every iteration. Both transmit
from the same location, 590kHz at 1700watts and 1430kHz at 5000watts.

You may be worrying about nothing if those
> interfering signals from such an antenna array are going to appear as S9
> plus 30dB or higher anyway.
>

Now with my Power cord CMC and the coax shorted at the far end. I can
get 14 stations 9 are 1 S unit or below 4 stations below 3 S units and
590 is 5.5 S units.
I'm going to spend some effort getting the coax below any leaves and in
contact with actual as much dirt as I can.

> I suspect the problem is less to do with a deficiency of the co-ax and
> more to do with a deficiency of receiver's input screening, hence my
> suggestion above.
>

?

Mikek

[mike]

On 6/9/2018 8:23 AM, amdx wrote:
> On 6/9/2018 8:20 AM, 69883925...@nospam.org wrote:
>> On a sunny day (Sat, 9 Jun 2018 07:31:35 -0500) it happened amdx
>> <noj...@knology.net> wrote in <pfghbc$8bi$1...@dont-email.me>:
>>
>>> I started an AM receive antenna installation by laying out 200ft of RG6
>>> coax. It's good coax with braid plus foil shield.
>>> The coax is on the ground, I shorted the end and connected the other
>>> end to my radio, there are no ground connections.
>>> The coax has 3 to 6 S units on my local radio stations.
>>> I want my coax to pick up as little signal as possible, because I want
>>> to install directional antenna on it.
>>>
>>> Next, I tried grounding the far end to a 5ft copper rod,
>>> this increased signal strength.
>>>
>>> Then I grounded the shield just before it enter the house,
>>> this increased signal strength.
>>>
>>> Removing the far end ground and having just the ground near the radio
>>> didn't help.
>>>
>>> I tried 3 different Chokes on the Coax at the radio, one monster choke
>>> is a very large potcore that I wound 15 turns of coax on, it has 25kohms
>>> of reactance at 1MHz.
>>> The chokes didn't help.
>>>
>>> I wound a 1:1 Isolation transformer installed at the radio.
>>> That didn't help.

How did you shield the chokes and transformers?
Can we assume that when you put shorting connector right at
the receiver, the interference went to zero?
And with the inductive gizmos connected and the shorting connector
at the INPUT to the inductive gizmos?
What happened with the short and connecting the coax shield to the
radio ground?

[amdx]

On 6/9/2018 2:06 PM, upsid...@downunder.com wrote:
> On Sat, 9 Jun 2018 07:31:35 -0500, amdx <noj...@knology.net> wrote:
>
>> I started an AM receive antenna installation by laying out 200ft of RG6
>> coax. It's good coax with braid plus foil shield.
>> The coax is on the ground, I shorted the end and connected the other
>> end to my radio, there are no ground connections.
>
> Is the receiver mains powered and especially double insulated ? If
> there are just an antenna connect tion but no ground connection, the
> antenna grounding happens through the signal ground through the power
> supply bridge rectifier and mains transformer capacitance to mains
> neutral. This can cause mains buzz (and possibly intermodulation
> products), if the rectifier diodes are not bypassed with small
> capacitors.
>

Yes, you are on to something, (see previous post)
I added CMC to the power cord and it did a lot.

> What is the radio input stage like ? Is it part of a ferrite rod
> antenna or perhaps a source follower intended for a whip antenna ? Or
> perhaps a proper 50/75 ohm input stage with a pi-section as in some
> car radios ?
>

I'm using an Icom R71A, it's old but a quality receiver.

> While impedance matching is not critical for reception especially on
> MW band, but proper impedance matching is critical for proper
> transmission line operation (such as interference intrusion) of the
> coax cable.
>
> Make sure that the receiver shows about 50 ohm termination resistance
> to the cable. If the receiver input impedance is much higher, you may
> need a step-up isolation transformer or a 50-100 ohm resistor across
> receiver input, with some loss of wanted distant signal.
>

Using 75 ohm coax and a 50 ohm input receiver.
I have a 1:1 isolation transformer, putting in actually increases
signals, BUT, I may need to put it in a shielded box.

[Mike Perkins]

What noise level do you get if you attach a 75R dummy load at the
antenna end?

Is there any change if you touch earth to coax earth to antenna earth?

If you use an attenuator, does the noise level drop more that the
attenuator value?

I'm wondering if there is some strong signal you're inadvertently
picking up.

--
Mike Perkins
Video Solutions Ltd
www.videosolutions.ltd.uk

[amdx]

The 75 ohm termination causes an extra 2 S units increase from 980kHz to
1480kHz, from 870 down the signals are about the same.
This is verses the Short.

>
> Is there any change if you touch earth to coax earth to antenna earth?

None that I have noticed.

[Unknown]

mpm <mpmi...@aol.com> wrote:

<snip>

> Also, are you concerned about lightning damage? (i.e., a lightning
> strike being conducted into your house/receiver? Something to consider?

Lightning surge protectors handle nearby strikes.

https://www.universal-radio.com/catalog/protect/5611.html

Your insurance agent handles direct strikes, provided you survive.

73,

--
Don Kuenz, KB7RPU

[George Herold]

Hmm, I'm not a radio guy, but isn't ground part of the antenna you'll
hang on the end? If so, then why is picking up radio signals when
you ground it, bad?

George H.

[Jeff Liebermann]

On Sat, 9 Jun 2018 07:31:35 -0500, amdx <noj...@knology.net> wrote:

Humble request: When you ask a question, tell the reader what you are
trying to accomplish first, and then provide the details, not the
other way around. I really hate reading such questions started at the
bottom.

>I started an AM receive antenna installation by laying out 200ft of RG6
>coax. It's good coax with braid plus foil shield.

Any reason you don't want to disclose the brand and model number?
There are literally hundreds of different mutations of RG-6/u with a
wide assortment of characteristics and deficiencies. Sometimes, I'm
thankful the Radio Shack is gone as their RG-6/u was abysmal with an
outer braid that was more decorative than functional, and a foil layer
that had a small but leaky slot due to lack of foil overlap.

> The coax is on the ground, I shorted the end and connected the other
>end to my radio, there are no ground connections.

Try a terminating resistor, not a short or open. See:
"Coaxial Cable Leakage"
<https://www.w8ji.com/coaxial_cable_leakage.htm>

>The coax has 3 to 6 S units on my local radio stations.
>I want my coax to pick up as little signal as possible, because I want
>to install directional antenna on it.

I'll spare you my rant on what I think of measuring signal levels in
S-Units:
<https://en.wikipedia.org/wiki/S_meter#Examples>
3 S-Units = 0.8 uV
6 S-Units = 6.3 uV
At 6 dB per S-Unit, that's quite a range of leakage.

> Next, I tried grounding the far end to a 5ft copper rod,
>this increased signal strength.

Yep, because you've created a loop where the coax is grounded at both
ends. If you want to ground the far end, you'll need an isolation
xformer at the receiver with no continuity between the shields.

>Then I grounded the shield just before it enter the house,
>this increased signal strength.

Same problem as before, except instead of 200ft of RG6 from receiver
to ground, you now have a shorter length of coax involved. It still a
ground loop, just a smaller one.

>Removing the far end ground and having just the ground near the radio
>didn't help.

Ok, you have leaky coax. Dig out the data sheet and calculate the
shielding effectiveness of your RG-6/u cable. The reason I wanted to
know the signal level in uV at the receiver is so that I could
calculate the shielding effectiveness. If you could provide a
reasonable guess for the field strength of whatever radio station
you're using for testing in mV/meter, and since we know the coax
length, I could calculate how much I would expect the center conductor
to pickup through the shielding.

These might help (or be of interest):
"AM Radio Field Strength Measurements with Confidence"
<http://www.ztechnology.com/pdf/AMTesting.pdf>

Field Intensity and Power Density:
<http://www.learnbydestroying.com/jeffl/coverage/VZW-water-plant/Field%20Intensity%20and%20Power%20Density.pdf>

Note that EVERYTHING assumes that the coax is properly terminated.
Forget about testing with opens and shorts on the end of the coax
cable.

> I tried 3 different Chokes on the Coax at the radio, one monster choke
>is a very large potcore that I wound 15 turns of coax on, it has 25kohms
>of reactance at 1MHz.
> The chokes didn't help.

Methinks (not sure) that's because the chokes don't do anything once
the RF leakage has arrived at the center conductor.

>I wound a 1:1 Isolation transformer installed at the radio.
>That didn't help.

That might help if you isolate the grounds across the isolation
xformer.

>I could invest in some Quad shield cable, but nope.
>I already have over 1000ft of RG6.

Note the insulation between each shield:
<http://www.tektel.com/COX3502/RG6-Coaxial-Cable-Quad-Shield-500-ft-18-AWG-Coax-Satellite-TV-Black.html>
If it really is leakage, it certainly will help. If you ground
alternate shield layers to each end of the cable, then there are no
ground loops. It probably also has lower leakage at 1MHz, but I'm too
lazy to look it up. Might be worth a try.

>The quietest so far is just the coax, no grounds.
>The chokes and transformer didn't seem to hurt, but they didn't help either.
>
>I also changed the short at the far end to a 75 ohm resistor.
>That didn't help.

Terminating the far end should have helped. Perhaps it's not really
leaking through the RG-6/u but rather directly into the receiver
through the case?

>Anyone have recommendations on how to quiet the coax?

Terminate the receiver input with just a 50 or 75 ohm termination.
Make sure it's shielded. If it still leaks, then try to determine if
it's leaking through the AC power line, or directly through the
plastic case. If necessary, put the receiver inside a metal box, and
see if that helps. If the power line leaks, try running the receiver
on a battery, or add a power line filter:
<http://www.te.com/usa-en/plp/corcom/Zn8v.html?q=&n=42254&type=products&samples=N>
In other words, forget about the RG-6/u until after you've leak
proofed the receiver.

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Jeff Liebermann]

On Sat, 9 Jun 2018 10:23:57 -0500, amdx <noj...@knology.net> wrote:

>When I installed my active mini whip I had terrible noise, I have
>already conquered electrical impulse noise.

I have the MiniWhip sold by someone in Leningrad on eBay. It's VERY
sensitive to grounding and ground loops:
"Grounding of MiniWhip and other active whip antennas"
<http://www.pa3fwm.nl/technotes/tn09d.html>
I had to move the MiniWhip to various location on my hillside before I
found a usable location. I current theory (pun intended) is that I'm
dealing with ground currents delivered by the electrical breaker box
ground rods on various houses. My ideal location turned out to be as
far away as possible from any of these ground rods. However, I don't
know if this is genuine or coincidence.

>Mostly outdoor lighting with sensors.

What kind of lighting? LED or incandescent? 117VAC LED bulbs are
sometimes rather noisy. What happens when you turn off the outdoor
lights?

[Alan Folmsbee]

As someone else already mentioned, use two 200 foot coax cables to
form a differential signal and a common mode rejection. If both coax outer
shields get the same noise, than a differential stage on the receiver
can be designed to reject common mode noise. The two inner wires will then
have the signal you want as a differential input. The common mode rejection
will be one goal.

[whit3rd]

On Saturday, June 9, 2018 at 5:31:44 AM UTC-7, amdx wrote:
> I started an AM receive antenna installation by laying out 200ft of RG6
> coax. It's good coax with braid plus foil shield.
> The coax is on the ground, I shorted the end and connected the other
> end to my radio, there are no ground connections.
> The coax has 3 to 6 S units on my local radio stations.

And this was with isolated power, in a Faraday shield cage? Every piece of
wire (and every human near the knobs) can pick up a signal, it doesn't have
to exist as a center-to-shield differential signal on the coax cable for that.

Replace the coax cable with a terminator plug, do you still pick up local
stations?

[Jasen Betts]

On 2018-06-09, amdx <noj...@knology.net> wrote:
> I started an AM receive antenna installation by laying out 200ft of RG6
> coax. It's good coax with braid plus foil shield.
> The coax is on the ground, I shorted the end and connected the other
> end to my radio, there are no ground connections.
> The coax has 3 to 6 S units on my local radio stations.
> I want my coax to pick up as little signal as possible, because I want
> to install directional antenna on it.

> Anyone have recommendations on how to quiet the coax?

Sounds like conducted noise. Try an isolating transformer on the coax.
this will have to give isolation up to a few megahertz so you'll probably
need to wind your own.

--
ت

[amdx]

On 6/9/2018 6:15 PM, Jeff Liebermann wrote:
> On Sat, 9 Jun 2018 07:31:35 -0500, amdx <noj...@knology.net> wrote:
>
> Humble request: When you ask a question, tell the reader what you are
> trying to accomplish first, and then provide the details, not the
> other way around. I really hate reading such questions started at the
> bottom.
>
>> I started an AM receive antenna installation by laying out 200ft of RG6
>> coax. It's good coax with braid plus foil shield.
>
> Any reason you don't want to disclose the brand and model number?
> There are literally hundreds of different mutations of RG-6/u with a
> wide assortment of characteristics and deficiencies. Sometimes, I'm
> thankful the Radio Shack is gone as their RG-6/u was abysmal with an
> outer braid that was more decorative than functional, and a foil layer
> that had a small but leaky slot due to lack of foil overlap.
>

Ok, I went out and looked at the numbers on the coax,

Genesis Cable Systems P/N 5010 RG 6/U 18 awg Broadband Premium
E175106 (UL) type CATV OR CL2 75C SUNRESS W/O #40874-295

>> The coax is on the ground, I shorted the end and connected the other
>> end to my radio, there are no ground connections.
>
> Try a terminating resistor, not a short or open. See:
> "Coaxial Cable Leakage"
> <https://www.w8ji.com/coaxial_cable_leakage.htm>
>

I have tried a 75 ohm termination, with that it has couple S units
more signal than with a short.

>> The coax has 3 to 6 S units on my local radio stations.
>> I want my coax to pick up as little signal as possible, because I want
>> to install directional antenna on it.
>
> I'll spare you my rant on what I think of measuring signal levels in
> S-Units:
> <https://en.wikipedia.org/wiki/S_meter#Examples>
> 3 S-Units = 0.8 uV
> 6 S-Units = 6.3 uV
> At 6 dB per S-Unit, that's quite a range of leakage.
>

Ya, I bought an HP 3586B to play these games, but haven't been able to
get it working.

ooh-- ya, my little ass'y didn't do that, ooh good catch.

I have an Icom R71A, I'll run over the above, but...
Yes, I believe in one of my posts made reference to putting a couple
of large CMC chokes on the Radio power cord and knock several signal
down to 1 S units or even 0 although I could hear there was audio.
Supper is Calling,
Thanks, Mike

[Phil Allison]

amdx wrote:
>
>
> I want my coax to pick up as little signal as possible, because I want
> to install directional antenna on it.
>
>

** So a *loop antenna* - right ??

Been using one with my hi-fi, tube AM radio for the last 40 years.

Started out following maker's instructions with a single turn wound around a window, then tried a much smaller loop with 10 turns. It worked just as well and could be oriented to eliminate 9kHz whistle or adjacent channels.

The connecting cable is light duty figure 8, sold for use with cheap speakers.

Until the loop is attached, it picks up nothing.

If I were to use a very long run then some heavier figure 8, split apart and twisted once per foot might be the go.



.... Phil

[upsid...@downunder.com]

On Sat, 9 Jun 2018 07:31:35 -0500, amdx <noj...@knology.net> wrote:

>I started an AM receive antenna installation by laying out 200ft of RG6
>coax. It's good coax with braid plus foil shield.

> The coax is on the ground, I shorted the end and connected the other
>end to my radio, there are no ground connections.

> The coax has 3 to 6 S units on my local radio stations.

>I want my coax to pick up as little signal as possible, because I want
>to install directional antenna on it.
>

> Next, I tried grounding the far end to a 5ft copper rod,
>this increased signal strength.
>

> Then I grounded the shield just before it enter the house,
>this increased signal strength.
>

>Removing the far end ground and having just the ground near the radio
>didn't help.
>

> I tried 3 different Chokes on the Coax at the radio, one monster choke
>is a very large potcore that I wound 15 turns of coax on, it has 25kohms
>of reactance at 1MHz.
> The chokes didn't help.
>

> I wound a 1:1 Isolation transformer installed at the radio.
>That didn't help.
>

> I could invest in some Quad shield cable, but nope.
>I already have over 1000ft of RG6.
>

> The quietest so far is just the coax, no grounds.
>The chokes and transformer didn't seem to hurt, but they didn't help either.
>
> I also changed the short at the far end to a 75 ohm resistor.
>That didn't help.

To measure the local station intrusion into the RG-6 coax, terminate
both ends with 75 ohm resistors. Using a high impedance floating
(battery powered) RF-voltmeter across one of the termination
resistors, measure the signal strength of the local stations.

With lack of proper measuring gear, the receiver might be usable. The
problem is that the input impedance (resistance and reactance) varies
across the receiver input terminals versus frequencies in the MW band.
The fact that the intrusion problem seems to be worst at lower end
suggests that the input impedance is rising towards lower frequencies.
Since to MW low end frequencies are close to the receiver low end (100
kHz), input filters may cause impedances wildly different from 50/75
ohms resistive.

If the receiver input impedance is high in MW band, directly
connecting the receiver across the 75 resistor night be OK.
Attractively increase the receiver end termination to 100 ohms so that
termination+receiver will be close to 75 ohm resistive. One thing is
to try putting an inductor across receiver input with 75 ohm reactance
at 300 kHz to compensate the input filter impedance variations.

****

Since the CM choke in the mains lead helped, there can be at least two
explanations.

1.) The local mains network works as an antenna and the receiver mains
filters are inadequate. After all in the old days, mains wiring,
telephone wires or telephone cable shields and even water and gas
pipes were used as antenna. Apparently this was so common that in some
radio amateur regulations, the use of such antennas for transmission
was forbidden :-).

2.) There is something wrong with the radio internal wiring. The
coaxial cable (shields) acts as an random wire antenna and the mains
provides the signal ground. Cutting this grounding path with a CM
choke seems to help the situation.

Is it possible to operate the receiver from a floating battery without
any mains or ground connections ?

[amdx]

A battery to run the radio is in my near future.
Mikek

[amdx]

On 6/9/2018 8:09 PM, amdx wrote:
> On 6/9/2018 6:15 PM, Jeff Liebermann wrote:
>> On Sat, 9 Jun 2018 07:31:35 -0500, amdx <noj...@knology.net> wrote:
>>
>> Humble request:  When you ask a question, tell the reader what you are
>> trying to accomplish first, and then provide the details, not the
>> other way around.  I really hate reading such questions started at the
>> bottom.
>>
>>> I started an AM receive antenna installation by laying out 200ft of RG6
>>> coax. It's good coax with braid plus foil shield.
>>
>> Any reason you don't want to disclose the brand and model number?
>> There are literally hundreds of different mutations of RG-6/u with a
>> wide assortment of characteristics and deficiencies.  Sometimes, I'm
>> thankful the Radio Shack is gone as their RG-6/u was abysmal with an
>> outer braid that was more decorative than functional, and a foil layer
>> that had a small but leaky slot due to lack of foil overlap.
>>
>
> Ok, I went out and looked at the numbers on the coax,
>
> Genesis Cable Systems P/N 5010  RG 6/U 18 awg Broadband Premium
> E175106 (UL) type CATV OR CL2 75C SUNRESS W/O #40874-295

I found the spec's
RG6/U
18gauge
CCS - Copper Clad Steel
40% Al - Shield
2.4 GHz
82% - Nominal Velocity of Propagation
16 pf/ft
0.275- dia.

The braid percentage at 40% is disappointing.
I expected so much more from a full 1000 ft reel I picked up
when a neighbor moved and left a big pile of junk for the
city to pick up. :-)
I do have some Amphenol T660-FVC, with 60% braid, not much better.
I'll probably experiment with twisted speaker wire, after I get the
battery to eliminate any connection to the AC line.
I put a question on the R-71A Yahoo group, asking if there has been
any internal problems causing RF to leak in the AC line.
I'm a doubter on that, but...
Mikek

[Jeff Liebermann]

On Sun, 10 Jun 2018 09:00:51 -0500, amdx <noj...@knology.net> wrote:

>On 6/9/2018 8:09 PM, amdx wrote:
>> Genesis Cable Systems P/N 5010  RG 6/U 18 awg Broadband Premium
>> E175106 (UL) type CATV OR CL2 75C SUNRESS W/O #40874-295
>
> I found the spec's
>RG6/U
>18gauge
>CCS - Copper Clad Steel
>40% Al - Shield
>2.4 GHz
>82% - Nominal Velocity of Propagation
>16 pf/ft
>0.275- dia.
>
> The braid percentage at 40% is disappointing.

Ummm... that's disgusting and might be the source of the leakage.
Actually, the correct term is "ingress" since the RF is going in, and
not out of the coax as it would be for "leakage".

>I expected so much more from a full 1000 ft reel I picked up
>when a neighbor moved and left a big pile of junk for the
>city to pick up. :-)

Well, you could use it to make a cheap distributed antenna system in
place of expensive leaky coax.
<https://www.google.com/search?q=leaky+coax+cable>

>I do have some Amphenol T660-FVC, with 60% braid, not much better.

I wonder what the "better" grades of RG-6/u offer for shielding?
<https://media.plattstatic.com/Products/2B572996-016A-4D3B-B781-A78A3FE2AA8D/2B572996-016A-4D3B-B781-A78A3FE2AA8D.pdf>
Looks like Honeywell Genesis etc cable comes in various grades.
Dual Shield:
- 100% Aluminum Foil Shield
- 45-80% Aluminum Braid Shield or 100% Tinned Copper Braid Shield
If it's 40%, then you have the cheapest grade of cable that they make.
Worse, when I tried to look for #5010 cable on the Honeywell web pile
at, nothings appeared:
<https://www.honeywellcable.com>
<https://www.honeywellcable.com/Pages/Category.aspx?category=videosurveillance&cat=HSG-GENESIS>
Of the various types they offer, the closest is "video surveillance"
cable, which is an indoor only type. It probably lacks UV protection
and might not survive very well outdoors.

Ok, let's try Commscope RG-6/u (non-plenum and non-direct burial):
<https://www.commscope.com/catalog/cables/product.aspx?id=33&sort=null&nrp=null&ShowObsolete=false&filter=865|4||0|||858|2||0||>
Looks like quad shielded:
<https://www.commscope.com/catalog/cables/product_details.aspx?id=34370>
isn't much better than the Honeywell cable. 60% on the inner braid
and 40% on the outer.

RG-58c/u (Belden 8262):
<https://catalog.belden.com/techdata/EN/8262_techdata.pdf>
is rated at 95% coverage, with only a braided wire shield and no
aluminum. Are you sure you want to use RG-6/u?

>I'll probably experiment with twisted speaker wire,

Ah, Zip cord. Instead, I suggest that you start with two parallel
runs of barbed wire. Look around the neighborhood. You might find
some near the junk pile where you found the RG-6/u.

>after I get the
>battery to eliminate any connection to the AC line.

If there's anything arriving via the power line, that should get rid
of it.

>I put a question on the R-71A Yahoo group, asking if there has been
>any internal problems causing RF to leak in the AC line.

I don't think anyone would notice unless the AM stations was next
door. Field strength has quite a bit to do with the severity of the
problem. Are you near an AM BCB station?

> I'm a doubter on that, but...

I think the fashionably correct term is that you're a denier.

[upsid...@downunder.com]

On Sat, 9 Jun 2018 07:31:35 -0500, amdx <noj...@knology.net> wrote:

Regarding using two RG-6 cables for a balanced feed, why not use some
ready made balanced coaxial cables such as the 93 ohm IBM Twinax.

In reality, any shielded twisted pair should work equally well at 1
MHz such as CAT5 FTP/STP.

Of course baluns are required at both ends in all these cases.

[piglet]

You could try inserting a 50 or 75ohm shielded in-line attentuator at
the receiver input. That would iron out receiver input impedence
mismatches. Then see how well the drop in received signal correlates
with the attenuator i.e. if the attentuator is 10dB and the receiver
level drops exactly 10dB then you know fersure the noise is pickedup in
the coax before the attenuator but if the received signal drops only 8dB
then you know some signal is getting in after the attenuator. Depends on
how accurate your S-meter is though :)

piglet

[amdx]

I could not get your 11:54 post to display.
That happens occasionally, sometimes if I try two or three times the
post will display, sometimes I wait an hour, sometimes I use my laptop
and it displays. Today, I read it in Google groups.

I'm not going to invest in any more coax.
OK, if I run the speaker wire and it doesn't prevent signals
better than the coax, then better coax could be in my future.

I'll digress a bit.
The antenna I'm connecting this coax to, is a BOG antenna.
My BOG is a short 300ft "Beverage On Ground".
Probably temporary, as it may interfere with my end goal antenna.

Because it's a short BOG, it won't have the great F/B ratio in the AM
band that I'd like, so I found a SW station at 5950 that is on the
backside of the antenna. On my long wire I have over 6 S units, on my
BOG I'm at Zero S units with very low but understandable audio.

The question remains, is the system dead at that frequency or is that
showing F/B ratio. Hope fully this evening I can find some other close
frequency signals to tell me it is working.

I need to take another stab at repairing my 3586B, this would be more
fun with that to measure with.


My end goal is four phased antennas, might be Deltas, might be
wire on the ground. I'm just in a holding pattern on that as I collected
info about best ways to prevent signal ingress and parts.
The AM radio gurus that use phased antennas have went to twisted
speaker wire because of ingress problems with coax. It hasn't been
stated, but that could be a trade off between buying expensive highly
shielded coax vs simple speaker wire that works just as well.
I have also corresponded with one that did use Cat5 and said it worked
fine, I also have a phased antenna write up that makes use of Cat5.
With the phased antennas, ingress will degrade the nice pattern
that you hope to get with a phased system.

OK, I now have my radio powered by battery only.
This may be a poor day to test a piece of coax, as it has rained.
That said, the battery connection seems reduce the high end signal
ingress down to about 950kHz, from there down there is a slight increase
in signal ingress.
This is with a short at the far end. A proper termination increases
all signals.

One last trek for today, into the the woods to reconnect my BOG to
the coax for tonight's listening pleasure.


Mikek

[Phil Allison]

amdx wrote:
>
>
> The antenna I'm connecting this coax to, is a BOG antenna.

** See:

https://en.wikipedia.org/wiki/Beverage_antenna

>
>
> My BOG is a short 300ft "Beverage On Ground".
> Probably temporary, as it may interfere with my end goal antenna.
>

** I hope nobody here has failed to recognise that "amdx" is barking mad.



.... Phil

[jurb...@gmail.com]

>"** I hope nobody here has failed to recognise that "amdx" is barking mad. "

Participation in SED proved that long ago.

[amdx]

Not able to get your post to display, had to look on google groups.

I have looked a dozens of Beverage sites, what did you want me to glean
from the wiki?

The wiki says nothing about BOGs.

Saying that I am barking mad is rather benign, congratulations, I hear
it's not always easy to get those meds correct.
I am curious what criteria you used to make that decision.
I hope you weren't going on beverages are long and terminated.
Mikek

[Phil Allison]

amdx wrote:
>
>
> Not able to get your post to display, had to look on google groups.
>
> I have looked a dozens of Beverage sites, what did you want me to glean
> from the wiki?
>
> The wiki says nothing about BOGs.

** The link was for the benefit of others, who like me had no f...ing idea what a Beverage antenna was.

I see you have discovered that co-ax is not ideal for loop antennas and that a simple twisted pair line may work better. Did you miss my info ?

> Saying that I am barking mad is rather benign,

** Yeah, I should have been harder.

> I am curious what criteria you used to make that decision.

** Your fanatical obsession with the pursuit of impossible goals is one.

That you are scheme to involve others is another.



.... Phil

[amdx]

On 6/10/2018 7:17 PM, Phil Allison wrote:
> amdx wrote:
>>
>>
>> Not able to get your post to display, had to look on google groups.
>>
>> I have looked a dozens of Beverage sites, what did you want me to glean
>> from the wiki?
>>
>> The wiki says nothing about BOGs.
>
>
> ** The link was for the benefit of others, who like me had no f...ing idea what a Beverage antenna was.
>
> I see you have discovered that co-ax is not ideal for loop antennas and that a simple twisted pair line may work better. Did you miss my info ?
>
>
>> Saying that I am barking mad is rather benign,
>
>
> ** Yeah, I should have been harder.
>

:-)

>
>> I am curious what criteria you used to make that decision.
>
>
> ** Your fanatical obsession with the pursuit of impossible goals is one.

I can't agree on Fanatical Obsession, I ran a coax, found it picked up
much more signal than I thought it would, I spent a few hours around a
work schedule (as little as it is) trying to reduce the signals.
I ask a few questions, checked my coax specs, found I could have
better shielding. That has me wondering how much a better coax would help.
I have some 93 ohm cable with a much better braid, but no foil, I
wonder if I should try it?
I may run the twisted speaker wire tomorrow.

> That you are scheme to involve others is another.

That's not barking mad, it's either diabolical, or I just admit
others know more than I do and I can use their knowledge in my pursuits.
The big plus, I'm having fun!
Mikek

[Phil Allison]

amdx wrote:
>
>
> Phil Allison wrote:
> > amdx wrote:
>
> >>
> >> The wiki says nothing about BOGs.
> >
> >
> > ** The link was for the benefit of others, who like me had no f...ing idea what a Beverage antenna was.
> >
> > I see you have discovered that co-ax is not ideal for loop antennas and that a simple twisted pair line may work better. Did you miss my info ?
> >
> >
> >> Saying that I am barking mad is rather benign,
> >
> >
> > ** Yeah, I should have been harder.
> >
> :-)
>
> >
> >> I am curious what criteria you used to make that decision.
> >
> >
> > ** Your fanatical obsession with the pursuit of impossible goals is one.
>
>
> I can't agree on Fanatical Obsession, I ran a coax,

** Your antenna project is absurd.

> I may run the twisted speaker wire tomorrow.
>

>

** It will still have RF interference / noise issues.

Cos the receiver MUST have a 600ohm, well balanced input.


** That you scheme to involve others is another.

>
> That's not barking mad,

** It absolutely is.



.... Phil

[Johnny B Good]

On Sun, 10 Jun 2018 20:32:27 -0700, Phil Allison wrote:

> amdx wrote:
>>
>>
>> Phil Allison wrote:
>> > amdx wrote:
>>
>>
>> >> The wiki says nothing about BOGs.
>> >
>> >
>> > ** The link was for the benefit of others, who like me had no f...ing
>> > idea what a Beverage antenna was.

That was an interesting article, especially the bit about the point made
in regard of the negative gain not being any impediment in the frequency
range of these long wire direction antennas due to the limitation imposed
by the high background QRN levels typically experienced in this part of
the radio spectrum.

The only serious omission I thought, was reference to its close cousin,
the Rhombic array, a sort of balanced version with actual gain making it
suitable for transmitting signals as well as receiving them, unlike the
Beverage which is suited only for receiving signals in that part of the
radio frequency spectrum typically plagued with high levels of QRN.

>> >
>> > I see you have discovered that co-ax is not ideal for loop antennas
>> > and that a simple twisted pair line may work better. Did you miss my
>> > info ?
>> >
>> >
>> >> Saying that I am barking mad is rather benign,
>> >
>> >
>> > ** Yeah, I should have been harder.

Not really, that was "hard" enough IMO. :-)

I think your posts could be a lot more persuasive if you could only
learn to lighten up a bit. You can achieve more with a kind word and a
gun than with a gun alone (especially when there's no justification for
"Going in, all guns blazing."... IMO).

>> >
>> :-)
>>
>>
>> >> I am curious what criteria you used to make that decision.
>> >
>> >
>> > ** Your fanatical obsession with the pursuit of impossible goals is
>> > one.

You forgot to add "IMHO" or "IMCO" or just "IMO"... imo. :-)

>>
>>
>> I can't agree on Fanatical Obsession, I ran a coax,
>
>
> ** Your antenna project is absurd.

Again, you forgot to add the all important "IMO". You seem to be rather
forgetful about making it clear that your sage comments are just
opinions. Perhaps you're presuming on your audience a little too much to
insert all those missing "IMO"s that your postings are so woefully
lacking. That's just sheer laziness, IMO.

>
>
>
>> I may run the twisted speaker wire tomorrow.
>>
>>
>
> ** It will still have RF interference / noise issues.
>
> Cos the receiver MUST have a 600ohm, well balanced input.

Why? It can be any convenient impedance ranging from 100Ω through to
1200Ω (or even higher - let's not allow ourselves to be limited by 'mere
convention'). :-)

I suspect you decided this random impedance value because of it being
the standard 'notional' impedance of balanced transmission lines used by
the telephone companies and used to calibrate the 0.775v 0dBmW reference
on LMS kit and adopted by the audio industry for all those VU meters that
adorn recording studio mixing desks and domestic tape recording equipment
et al. I do believe this statement was crying out for yet another "IMO".

>
>
> ** That you scheme to involve others is another.

That's a rather sinister interpretation (IMO) of the point of AMDX's
post which I think (also IMO) is more a cry for help from others more
experienced and/or knowledgeable with/about the problems he's having with
his (not unreasonable, IMO) quest to build a directional MF antenna for
his DX SWL activities.

>
>
>> That's not barking mad,
>
>
> ** It absolutely is.

Only in your opinion (considered or not). :-)

In my opinion, I think AMDX is simply being a little more ambitious than
the more typically laid back "DX SWL" enthusiast. He's been asking all
the right questions about a subject that can seem more 'art' than
'science'.

--
Johnny B Good

[mako...@yahoo.com]

op,
i think someone else already said this but your issue is not the coax.

Your issue is the input circuit to the radio.

Make sure the input terminal that you connect the shield of the coax to
is a good ground for the radio, I don't mean you need a ground rod there I mean
it must be the RADIO ground.

Is it a good connection to the radio chassis?

[amdx]

There has been a lot of talk about my radio.
I don't believe the radio is the problem.
I'm using an Icom R-71A, driving the 50 ohm input.
> https://www.eham.net/reviews/detail/496


Connecting a 75 ohm cable to a 50 ohm input for receiving
is not perfect, but in most cases it won't be noticed.
I'll be running a twist pair maybe today, That is pretty close to
100 ohms, I will try that with and without a 2 to 1 matching transformer.

Mikek

[amdx]

On 6/10/2018 10:32 PM, Phil Allison wrote:
> amdx wrote:
>>
>>
>> Phil Allison wrote:
>>> amdx wrote:
>>
>>>>
>>>> The wiki says nothing about BOGs.
>>>
>>>
>>> ** The link was for the benefit of others, who like me had no f...ing idea what a Beverage antenna was.
>>>
>>> I see you have discovered that co-ax is not ideal for loop antennas and that a simple twisted pair line may work better. Did you miss my info ?
>>>
>>>
>>>> Saying that I am barking mad is rather benign,
>>>
>>>
>>> ** Yeah, I should have been harder.
>>>
>> :-)
>>
>>>
>>>> I am curious what criteria you used to make that decision.
>>>
>>>
>>> ** Your fanatical obsession with the pursuit of impossible goals is one.
>>
>>
>> I can't agree on Fanatical Obsession, I ran a coax,
>
>
> ** Your antenna project is absurd.

What is absurd about a BOG antenna?
> https://tinyurl.com/yc6n46yv

>
>
>
>> I may run the twisted speaker wire tomorrow.
>>
>
>>
> ** It will still have RF interference / noise issues.

I'll prove that to myself.

>
> Cos the receiver MUST have a 600ohm, well balanced input.

You are moving out of your knowledge base.

A BOG antenna has an impedance from 200 to 350 ohms.
A transformer matches the antenna to the feedline.
I may or may not match the feed line to my 50 ohm receiver input.
I may inductively load my BOG anf that can raise the impedance much
higher. Calling for a different transformer.

>
>
> ** That you scheme to involve others is another.
>
>>
>> That's not barking mad,
>
>
> ** It absolutely is.

Is that a GOD complex you have there?

>
>
>
> .... Phil
>

[amdx]

Hi Johhny,
I understand your wanting change to Phil, but he has been here a long
time and with his deficient interpersonal skills. No amount of feedback
has made any difference.
And besides if you did correct his way, you'd spoil all the fun!
Mikek
PS. IMHO!

[amdx]

On 6/10/2018 10:32 PM, Phil Allison wrote:
> amdx wrote:
>>
>>
>> Phil Allison wrote:
>>> amdx wrote:
>>
>>>>
>>>> The wiki says nothing about BOGs.
>>>
>>>
>>> ** The link was for the benefit of others, who like me had no f...ing idea what a Beverage antenna was.
>>>
>>> I see you have discovered that co-ax is not ideal for loop antennas and that a simple twisted pair line may work better. Did you miss my info ?
>>>
>>>
>>>> Saying that I am barking mad is rather benign,
>>>
>>>
>>> ** Yeah, I should have been harder.
>>>
>> :-)
>>
>>>
>>>> I am curious what criteria you used to make that decision.
>>>
>>>
>>> ** Your fanatical obsession with the pursuit of impossible goals is one.
>>
>>
>> I can't agree on Fanatical Obsession, I ran a coax,
>
>
> ** Your antenna project is absurd.
>
>
>
>> I may run the twisted speaker wire tomorrow.
>>
>
>>
> ** It will still have RF interference / noise issues.
>
> Cos the receiver MUST have a 600ohm, well balanced input.
>
>

With my 200+ft of coax I received 13 stations. One had a signal strength
of 5.5 S units, 2 had 3 S units, 4 had 1 or 2 S units, and 6 had zero S
units but were audible.
Ran my 225 ft of twisted speaker wire, connected it to the 50 ohm
input of my radio through a 1 to 1 transformer.
I now only have 4 audible stations (vs 13) 3 with Zero S units and 1
that bounces to 0.5 S units.
Hooked it up to the BOG and it works, However bad day for any testing,
lightning all around me.
My conclusion, twisted speaker wire is a winner with respect to signal
ingress.
Mikek

[Phil Allison]

Johnny B Good wrote:

> Phil Allison wrote:
>
> >>
> >> >> The wiki says nothing about BOGs.
> >> >
> >> >
> >> > ** The link was for the benefit of others, who like me had no f...ing
> >> > idea what a Beverage antenna was.
>
> That was an interesting article, especially the bit about the point made
> in regard of the negative gain not being any impediment in the frequency
> range of these long wire direction antennas due to the limitation imposed
> by the high background QRN levels typically experienced in this part of
> the radio spectrum.

>
> >> >

> >> > I see you have discovered that co-ax is not ideal for loop antennas
> >> > and that a simple twisted pair line may work better. Did you miss my
> >> > info ?
> >> >
> >> >
> >> >> Saying that I am barking mad is rather benign,
> >> >
> >> >
> >> > ** Yeah, I should have been harder.
>
> Not really, that was "hard" enough IMO. :-)
>

** IOW it was accurate ?

> I think your posts could be a lot more persuasive if you could only
> learn to lighten up a bit. You can achieve more with a kind word and a
> gun than with a gun alone (especially when there's no justification for
> "Going in, all guns blazing."... IMO).
>

** "amdx" is an incorrigible troll with a one track mind, has been for nearly 20 years. Be a crime to encourage him.

> >> >> I am curious what criteria you used to make that decision.
> >> >
> >> >
> >> > ** Your fanatical obsession with the pursuit of impossible goals is
> >> > one.
>
> You forgot to add "IMHO" or "IMCO" or just "IMO"... imo. :-)

** I did not forget - demonstrable facts need no such qualifications.

> >>
> >> I can't agree on Fanatical Obsession, I ran a coax,
> >
> >
> > ** Your antenna project is absurd.
>
> Again, you forgot to add the all important "IMO".
>

** What is NOT absurd about it ??

There are way to many absurd people posting ratbag notions here.

You seem to be rather
> forgetful about making it clear that your sage comments are just
> opinions.

** I see you cannot tell the difference.

Makes you a "troll feeder".

Where does it say " crackpots welcome" here ??

>
> >
> >> I may run the twisted speaker wire tomorrow.
> >>
> >>
> >
> > ** It will still have RF interference / noise issues.
> >
> > Cos the receiver MUST have a 600ohm, well balanced input.
>
> Why?

** My point was about the need for "well balanced" - 600ohms will likely work well.

> >
> > ** That you scheme to involve others is another.
>
> That's a rather sinister interpretation
>

** He obfuscates, fails to reaveal his purpose and trolls on a NG that has nothing to do with his mad obsession so he can waste the time of others.

That's sinister enough.

> In my opinion, I think AMDX is simply being a little more ambitious than
> the more typically laid back "DX SWL" enthusiast. He's been asking all
> the right questions about a subject that can seem more 'art' than
> 'science'.
>

** I have no idea what "amdx" is really after and he never reveals it.

He ought to find a NG with like minded folk and post there.



.... Phil

[Phil Allison]

amdx wrote:


> >
> > ** Your antenna project is absurd.
>
> What is absurd about a BOG antenna?

** Everything.

>
> >
> >> I may run the twisted speaker wire tomorrow.
> >>
> >
> >>
> > ** It will still have RF interference / noise issues.
>
> I'll prove that to myself.
>

** It will happen, like it or not.

> >
> > Cos the receiver MUST have a 600ohm, well balanced input.
> You are moving out of your knowledge base.
>

** That is massive false assumption.

> A BOG antenna has an impedance from 200 to 350 ohms.
> A transformer matches the antenna to the feedline.
> I may or may not match the feed line to my 50 ohm receiver input.

** Shame how a twisted, balanced signal line does not work unless the termination is well balanced.

>
> > ** That you scheme to involve others is another.
> >
> >>
> >> That's not barking mad,
> >
> >
> > ** It absolutely is.
>
> Is that a GOD complex you have there?
>

** Now you sound like a lunatic, a couple of grades up from a mere ratbag.

Find another NG to haunt.



.... Phil

[Phil Allison]

amdx wrote:

>
> Ran my 225 ft of twisted speaker wire, connected it to the 50 ohm
> input of my radio through a 1 to 1 transformer.
>

** So you balanced the receiver's input by floating it or is there a CT?

> My conclusion, twisted speaker wire is a winner with respect to signal
> ingress.

** No fooling ......

Who woulda thunk.


..... Phil

[DecadentLinux...@decadence.org]

amdx <noj...@knology.net> wrote in news:pfhbau$cdm$1...@dont-email.me:

snip

> I have a 1:1 isolation transformer, putting in actually increases
> signals, BUT, I may need to put it in a shielded box.
>
No shit!

[amdx]

>
> ** I have no idea what "amdx" is really after and he never reveals it.

> .... Phil
>

The subject line was to tricky for you?
Mikek

[Phil Allison]

** Now you sound like a lunatic, a couple of grades up from a mere ratbag.

Find another NG to haunt.

Or a mental hospital.

[upsid...@downunder.com]

Since using a CM choke on the _mains_ cable changes the coaxial
leakage, it is not just a question if the coax cable in isolation, but
the whole system seems to have an effect. Knowing the whole system
makes it possible to give meaningful comments.

[amdx]

On 6/9/2018 7:09 PM, Jasen Betts wrote:

> On 2018-06-09, amdx <noj...@knology.net> wrote:
>> I started an AM receive antenna installation by laying out 200ft of RG6
>> coax. It's good coax with braid plus foil shield.
>> The coax is on the ground, I shorted the end and connected the other
>> end to my radio, there are no ground connections.

>> The coax has 3 to 6 S units on my local radio stations.
>> I want my coax to pick up as little signal as possible, because I want
>> to install directional antenna on it.
>

>> Anyone have recommendations on how to quiet the coax?
>
>
> Sounds like conducted noise. Try an isolating transformer on the coax.
> this will have to give isolation up to a few megahertz so you'll probably
> need to wind your own.
>
After installing a twisted speaker wire, connecting it to my 300ft
Beverage On the Ground, and with an approximately 250 ohm terminating
resistor. I tested a little last evening.
Here's a short video of one frequency while I switch between the BOG,
Longwire and Mini Whip antennas.

> https://www.youtube.com/watch?v=q8rBb2v13tg

This WCKY 600 miles N of me, which is approximately the direction the
antenna points.

You can clearly see the BOG has directional characteristics.
Still more to do, rewind the transformer with a different core and
ratio, install a vactrol to allow remote adjustment of the termination
and install loading coils to make the BOG look longer.

Mikek

[69883925...@nospam.org]

amdx <noj...@knology.net> wrote in <pfghbc$8bi$1...@dont-email.me>:

>I started an AM receive antenna installation by laying out 200ft of RG6
>coax. It's good coax with braid plus foil shield.

I wonder if anybody noticed that
200 feet = 60.96 meters

4 x 60.96 = 243.84 meter

243.84 meter = 1.230315 MHz

MW range in US is from 525 kHz to 1705 kHz.

So that coax, all by itself,
makes a perfect 1/4 wavelength 50 Ohm match antenna for that MW band,
is right in the center of it.

Try again with the coax shorted at the antenna input.
Receiver could well be overloaded, signal via coax screen.

[Jeff Liebermann]

On Mon, 11 Jun 2018 11:11:57 -0500, amdx <noj...@knology.net> wrote:

> There has been a lot of talk about my radio.

Well yes. Talk is what they do on the radio.

>I don't believe the radio is the problem.
>I'm using an Icom R-71A, driving the 50 ohm input.
>> https://www.eham.net/reviews/detail/496

Have you ever measured the input impedance vs frequency of a wide
coverage receiver input? I have and it's awful. If you have an
MFJ-259/269 or equivalent analyzer, it's easy to do. Don't worry
about blowing up your receiver RF stage. The MFJ analyzers don't
generate very much RF. You might be lucky and find that it's
somewhere near 50 ohms at 1MHz, but I suspect that it will not even be
close.

Incidentally, I've also measured the output impedance of various
transmitters (using a different method) and found a similar problem.
The output impedance is also nowhere near 50 ohms.

>Connecting a 75 ohm cable to a 50 ohm input for receiving
>is not perfect, but in most cases it won't be noticed.

I do it all the time. If lazy, I just ignore the 0.2dB mismatch loss.
If I'm trying to make accurate measurements, I use a minimum loss pad
(-5.71dB):
<https://www.microwaves101.com/encyclopedias/l-pads#minloss>
<http://ham-radio.com/k6sti/match.htm>
<https://www.pasternack.com/matching-pads-category.aspx>

>I'll be running a twist pair maybe today, That is pretty close to
>100 ohms, I will try that with and without a 2 to 1 matching transformer.

I hope you mean CAT5 cable. It should work if you do everything
possible to keep the line balanced. That means fairly straight runs,
wide curves, and keeping the cable away from objects. The problems
are usually keeping the line balanced when it goes through a hole in
the wall, or when just laying on the ground. At 1 MHz, you should be
ok with being a little sloppy.

CAT5e and CAT6 have a big advantage. The cable has 4 pairs of wire,
all of which are about 100 ohms, with different twist rates to
minimize crosstalk between pairs. They do this with slight changes in
the wire gauges. My failed plan was to build a 4 element doppler
direction finder with no electronics in the antenna assembly.
Maintaining balance proved to be difficult, so the design reverted to
using 4 coaxial cables, which was both more expensive and messy
because all 4 cables had to be cut from the same roll. We eventually
convinced the customer that some electronics in the antenna was
necessary.

However, if you don't need direction finder type precision, CAT6 still
might work for a directional AM BCB antenna project. Something like
this:
<https://www.dxengineering.com/search/department/antennas/section/receive-antennas-and-arrays/part-type/antenna-phasing-and-noise-cancelling/unit-type/directional-antenna-system/product-line/dx-engineering-active-antenna-phasing-systems>
but with no remote RF amps and using CAT6 instead of coax.

Good luck.

[Gerhard Hoffmann]

Am 12.06.2018 um 18:15 schrieb Jeff Liebermann:
> On Mon, 11 Jun 2018 11:11:57 -0500, amdx <noj...@knology.net> wrote:
>
>> There has been a lot of talk about my radio.
>
> Well yes. Talk is what they do on the radio.
>
>> I don't believe the radio is the problem.
>> I'm using an Icom R-71A, driving the 50 ohm input.
>>> https://www.eham.net/reviews/detail/496
>
> Have you ever measured the input impedance vs frequency of a wide
> coverage receiver input? I have and it's awful. If you have an
> MFJ-259/269 or equivalent analyzer, it's easy to do. Don't worry
> about blowing up your receiver RF stage. The MFJ analyzers don't
> generate very much RF. You might be lucky and find that it's
> somewhere near 50 ohms at 1MHz, but I suspect that it will not even be
> close.
>
> Incidentally, I've also measured the output impedance of various
> transmitters (using a different method) and found a similar problem.
> The output impedance is also nowhere near 50 ohms.
>
>> Connecting a 75 ohm cable to a 50 ohm input for receiving
>> is not perfect, but in most cases it won't be noticed.

Tuning a receiver input for optimum noise matching will
nearly never happen at max. power matching, and power
matching a generator will guarantee an efficiency < 0.5.

regards, Gerhard

[Steve Wilson]

Gerhard Hoffmann <g...@hoffmann-hochfrequenz.de> wrote:

> Tuning a receiver input for optimum noise matching will
> nearly never happen at max. power matching, and power
> matching a generator will guarantee an efficiency < 0.5.

> regards, Gerhard

200 ft of coax will introduce losses by itself. One solution may be to add a
preamplifier at the antenna to drive the coax. Add matching network at the
receiver as needed.

[mako...@yahoo.com]

the issue is not the impedance mis match
the issue is the quality of the ground connection at the Rx input.

Do this test.

Connect only the shield of the coax to the ground terminal of the Rx. Leave coax center conductor unconncted

do you receive anything?

now short the hot input to the ground also.

In both cases, if you receive anything, it is due to imperfect grounding and or shielding within the receiver and has nothing to do with the coax.

have fun

mark

[Johnny B Good]

On Mon, 11 Jun 2018 11:11:57 -0500, amdx wrote:

> On 6/11/2018 10:09 AM, mako...@yahoo.com wrote:
>> op,
>> i think someone else already said this but your issue is not the coax.
>>
>> Your issue is the input circuit to the radio.
>>
>> Make sure the input terminal that you connect the shield of the coax to
>> is a good ground for the radio, I don't mean you need a ground rod
>> there I mean it must be the RADIO ground.
>>
>> Is it a good connection to the radio chassis?
>>
>>
>>
> There has been a lot of talk about my radio.
> I don't believe the radio is the problem.
> I'm using an Icom R-71A, driving the 50 ohm input.
>> https://www.eham.net/reviews/detail/496

Very impressive reviews, including a few by operators who rated it
better than the professional/commercial communications receivers they
were using alongside of it. The pictures suggest the use of a steel case
so any thoughts of it allowing stray high field strength signals leaking
past the input screening can be pretty well set aside.

However, that doesn't preclude the possibility of mains borne
interference being conducted into the receiver via its power supply
connections. Testing with a 12v SLA is an effective way to remove such
potential interference sources from the equation. Not only does it
eliminate ingress via the power supply connections, it also eliminates
the possibility of interference being conducted onto the outer braid of
the co-axial feeder where it can then reach the antenna feed point and so
appear as an interference signal received by the antenna.

>
> Connecting a 75 ohm cable to a 50 ohm input for receiving
> is not perfect, but in most cases it won't be noticed.

Very true, even in the case of a transceiver where it is of some
significance to the Tx output filter, feeding a 75Ω line from a 50Ω
filtered Tx output is normally not that much of an issue in practice
(especially if a high vswr protection circuit has been included).

> I'll be running a twist pair maybe today, That is pretty close to
> 100 ohms, I will try that with and without a 2 to 1 matching
> transformer.

If you're referring to the turns ratio of the matching transformer,
don't forget that a 2:1 turns ratio results in a 4:1 impedance
transformation ratio.

Conventional transformer winding construction practice for mains and
audio frequencies doesn't work so well at MF and HF frequencies due to
the leakage inductance issue so such transformers are normally made up
using bifilar and trifilar windings (perhaps even quadrifilar and
quintifilar in more extreme cases) to minimise leakage inductance. The
consequence of this is you rarely see such MF/HF transformers used to
obtain impedance ratios outside of the common 1:1 and 4:1 options.

The classic balun transformer used to connect a 75Ω co-axial feeder
(orthogonally) to the 72Ω centre fed half wave antenna is a trifilar
wound 1:1:1 auto-transformer with all three windings in series phase
aiding. The result is an auto transformer with two taps at one third and
two thirds the way along from either end.

Working from left to right, the connections used for the antenna are LHS
and Tap#2 with the feeder braid connected to Tap#1 and the co-ax inner to
the RHS end connection. This provides antenna connections that are
balance with respect to the braid connection (centre tap of the section
between the LHS and Tap#2) and a 1:1 turns ratio between the feeder
connection (Tap#1 and the RHS connection).

If you're using a centre fed folded dipole with a 300Ω feedpoint
impedance, you could use an even simpler bifilar wound balun with your
75Ω co-axial feeder.

A better option may be to replace that 100Ω speaker wire with a 300Ω
balanced feeder connected to a bifilar isolating transformer which
provides a galvanically isolated link to a conventional 2:1 bifilar wound
balun feeding the Rx antenna socket. If you can arrange for the feeder
impedance to be 200Ω, the Rx will see a 50Ω impedance instead of the 75Ω
in the 300Ω feeder case. However, the exact impedance value as you stated
before, is far from critical for an Rx only setup.

The real benefit of using a balun and isolating transformer in this case
will be to remove galvanic connections between the feeder and the station
and antenna grounds and thus attenuate any interfering signals which may
be polluting the station's local grounding point from travelling along
the feeder as a common mode signal voltage to be injected into the
antenna connection.

Mirroring the 1:1 isolation transformer and 2:1 balun setup at the
station end will provide even greater attenuation to any such
interference arising on the station's local grounding point (a balun will
be required regardless). In this case though, you'll need your balun's
unbalanced port to be a much higher impedance than the 50Ω or 75Ω
impedances used at the station end of the circuit.

It's *so* not easy to achieve all of that in one step that I'd recommend
the use of a third transformer to translate the notional 75Ω output of
the balun into either a 300Ω (simple 2:1 bifilar wound auto-transformer)
or else a 675Ω (3:1 trifilar) impedance match.

Attempting to get a better impedance match with non-standard broadband
matching transformer ratios is unlikely to improve the situation. As is
so often the case, compromise rules the day. Impedance matching in this
case is secondary to achieving a galvanically isolated balanced
transmission line setup to minimise unwanted signal pick up. Since the
impedance of the Beverage antenna is expected to lie somewhere between
300Ω and 800Ω, it seems to me that you'd be better off testing both 2:1
bifilar and 3:1 trifilar transformers and choosing the least worst one.

Keep in mind that if you're going to replace a co-axial feeder with a
balanced line feeder, unless you're using shielded twisted pair cable,
you'll need to support it clear of any ground influences that might upset
the balance, particularly true with the classic 300Ω ribbon cable
transmission line. Regularly spaced support posts with insulated carriers
to keep the ribbon cable at least a foot or so clear of the ground and
any patches of long grass should suffice, not forgetting to transpose at
every supporting point through a 180 degree rotation for good measure.

If you're using a high enough number of supporting posts along the line
route, it might be better to transpose through either a consistent
clockwise (or anti-clockwise - pick one or the other and stick to it) 90
degrees rotation at each support point along the route. If eliminating
unwanted signal pickup is the name of the game, then transposition isn't
optional, it's demanded (at least in the case of open wire or ribbon
cable feeders).

--
Johnny B Good

[amdx]

A copy of my 7:03 am post.

After installing 237ft of twisted speaker wire, connecting it to my

[Mike Perkins]

I was wondering something along similar lines, and so wondering the
effect of an attenuator on the receiver input (as posted earlier), and
if the noise went down disproportionately.


--
Mike Perkins
Video Solutions Ltd
www.videosolutions.ltd.uk

[amdx]

Nope, I ran an 18 gauge twisted speaker wire.
From a previous post,

With my 200+ft of coax I received 13 stations. One had a signal strength
of 5.5 S units, 2 had 3 S units, 4 had 1 or 2 S units, and 6 had zero S
units but were audible.

Ran my 237 ft of twisted speaker wire, connected it to the 50 ohm

input of my radio through a 1 to 1 transformer.

I now only have 4 audible stations (vs 13) 3 with Zero S units and 1

that bounces up to 0.5 S units.

Hooked it up to the BOG and it works, However bad day for any testing,
lightning all around me.

My conclusion, twisted speaker wire is a winner with respect to signal
ingress.

Mikek

[whit3rd]

On Monday, June 11, 2018 at 2:01:08 PM UTC-7, amdx wrote:

> With my 200+ft of coax I received 13 stations. One had a signal strength
> of 5.5 S units, 2 had 3 S units, 4 had 1 or 2 S units, and 6 had zero S
> units but were audible.
> Ran my 225 ft of twisted speaker wire, connected it to the 50 ohm
> input of my radio through a 1 to 1 transformer.

> I now only have 4 audible stations ...

> My conclusion, twisted speaker wire is a winner with respect to signal
> ingress.

Well, no, that ignores on your grounding. The coax long line was taking
in signal on its shield, and because of ground-at-both-ends,
that made a ground loop. The inner conductor was doing inductive
pickup (it's an accidental transformer) of pickup by the loop.

Any scheme for making a much lower ground loop current, like ground-isolation at both ends,
would make the coax a good receiver-of-small-signals shield. Tricky
possibilities include putting power onto the coax and preamplifying
at the antenna end, which would help the impedance issue.

[amdx]

On 6/12/2018 3:24 PM, whit3rd wrote:
> On Monday, June 11, 2018 at 2:01:08 PM UTC-7, amdx wrote:
>
>> With my 200+ft of coax I received 13 stations. One had a signal strength
>> of 5.5 S units, 2 had 3 S units, 4 had 1 or 2 S units, and 6 had zero S
>> units but were audible.
>> Ran my 225 ft of twisted speaker wire, connected it to the 50 ohm
>> input of my radio through a 1 to 1 transformer.
>> I now only have 4 audible stations ...
>> My conclusion, twisted speaker wire is a winner with respect to signal
>> ingress.
>
> Well, no, that ignores on your grounding. The coax long line was taking
> in signal on its shield, and because of ground-at-both-ends,

I tried it without ground on either end and an isolation transformer.

[Johnny B Good]

On Tue, 12 Jun 2018 12:47:03 -0500, amdx wrote:

> A copy of my 7:03 am post.
>
> After installing 237ft of twisted speaker wire, connecting it to my
> 300ft Beverage On the Ground, and with an approximately 250 ohm
> terminating resistor. I tested a little last evening.
> Here's a short video of one frequency while I switch between the BOG,
> Longwire and Mini Whip antennas.
>
> > https://www.youtube.com/watch?v=q8rBb2v13tg

Quite a clear demonstration of the directionality of the "BoG" which I
initially assumed was simply strung out on supporting poles a few feet
above the terrain as per the standard Beverage antenna setup.

Can you confirm that your BoG is simply 300 foot of insulated wire laid
straight onto the ground with its far end terminated with a 250Ω non
inductive resistor connection to a grounding rod?

>
> This WCKY 600 miles N of me, which is approximately the direction the
> antenna points.
>
> You can clearly see the BOG has directional characteristics. Still
> more to do, rewind the transformer with a different core and
> ratio, install a vactrol to allow remote adjustment of the termination
> and install loading coils to make the BOG look longer.
>

I had to look up the word "Vactrol". :-)

I'm not so sure adding loading coils will improve your BoG antenna.
Using loading coils to make an antenna look electrically longer reduces
efficiency. A loading coil to bring a short whip antenna to resonance to
improve its matching, results in greater current flow which increases the
I squared losses in both the coil and the whip and ground resistances.

Far better, I'd have thought, to extend the antenna length if you can,
especially when the directional properties seem to be essentially a
function of actual, rather than electrical length in this case.

Still, I have no expertise in the matter of such end fed long wire
arrays due to lack of real estate in which to lay one out, so I may be
overstating the loading coil issue.

--
Johnny B Good

[amdx]

On 6/12/2018 8:09 PM, Johnny B Good wrote:
> On Tue, 12 Jun 2018 12:47:03 -0500, amdx wrote:
>
>> A copy of my 7:03 am post.
>>
>> After installing 237ft of twisted speaker wire, connecting it to my
>> 300ft Beverage On the Ground, and with an approximately 250 ohm
>> terminating resistor. I tested a little last evening.
>> Here's a short video of one frequency while I switch between the BOG,
>> Longwire and Mini Whip antennas.
>>
>> > https://www.youtube.com/watch?v=q8rBb2v13tg
>
> Quite a clear demonstration of the directionality of the "BoG" which I
> initially assumed was simply strung out on supporting poles a few feet
> above the terrain as per the standard Beverage antenna setup.
>
> Can you confirm that your BoG is simply 300 foot of insulated wire laid
> straight onto the ground with its far end terminated with a 250Ω non
> inductive resistor connection to a grounding rod?

It is 300ft + /- a few, the wire is army field wire like this,
http://armysurpluswarehouse.com/wd-1a-tt-dr-8-a-telephone-cable/
Note it is actually 2 conductor wire, but I have tied them together at
each end. (I have thought about removing one of the wires, if I got good
info that it would make any difference I would do it)
I laid it on the ground as best I could, This is somewhat of a pine
woods, so lots of pine needles and decaying vegetation on top of the dirt.
I have 3 non inductive resistors in series (I didn't have the proper
value) with a pot across them for the termination. I expected to make
adjustments and test, but since I started we have had rain and lightning
storms around, makes for tough listening.
A 5 foot copper pipe driven in to the ground at each end.
For the transformer I used a 35T0501-10H toroid with I think? 8 and 16
turns. This is probably not a good design, I started with wanting to be
able to receive 200kHz beacons, so it has more turns than needed.
I have the recommended Material 73 binocular cores on order to make a
better transformer.
I don't have an ideal property, There is a a wooded area behind my
house. I spent several days clearing brush and plants for a straight
line through the woods. Part of it is a drainage area and gets water
that drains through when it rains hard.
The wire is straight, but terrain is not level, the wire follows the
terrain.

>
>>
>> This WCKY 600 miles N of me, which is approximately the direction the
>> antenna points.
>>
>> You can clearly see the BOG has directional characteristics. Still
>> more to do, rewind the transformer with a different core and
>> ratio, install a vactrol to allow remote adjustment of the termination
>> and install loading coils to make the BOG look longer.
>>
>
> I had to look up the word "Vactrol". :-)

I learned about them 15 years ago when I built a rotatable Flag
antenna with variable termination. I still have it and the power supply
I used for the adjustment.

>
> I'm not so sure adding loading coils will improve your BoG antenna.
> Using loading coils to make an antenna look electrically longer reduces
> efficiency. A loading coil to bring a short whip antenna to resonance to
> improve its matching, results in greater current flow which increases the
> I squared losses in both the coil and the whip and ground resistances.

I am a little perplexed by the info I read that says the BOG is a
inefficient low signal antenna. I'm not finding that. If you look at the
video again, you can see the S meter needle shows only 1 to 1- 1/2 less
S units than the 150ft longwire.
Re: the loading coils, here's where I got that.
> https://www.w8ji.com/slinky_and_loaded_beverages.htm
He does not mention inductors specifically for a BOG only a beverage,
and I think being on the ground already slows the VP. I don't think
efficiency is something to be to worried about with a BOG. The article
even references low Q inductors. I'm thinking a BOG will need less
inductance than a regular beverage to get to the optimum.
Anyway, it's an experiment for the future.

Surge impedance is mentioned in the article, is this different than
just plain impedance?

> Far better, I'd have thought, to extend the antenna length if you can,
> especially when the directional properties seem to be essentially a
> function of actual, rather than electrical length in this case.

I'm boxed in on one end by a neighbor's fence and by a 5 lane road on
the other.

> Still, I have no expertise in the matter of such end fed long wire
> arrays due to lack of real estate in which to lay one out, so I may be
> overstating the loading coil issue.
>

I've been searching for more info, but didn't find any.

Mikek

[upsid...@downunder.com]

Power vs. noise match s an issue at UHF and up, but not an issue at 1
MHz with huge band noise.

[tom]

"amdx" <noj...@knology.net> wrote in message
news:pfq3ci$e98$1...@dont-email.me...

> On 6/12/2018 8:09 PM, Johnny B Good wrote:
>> On Tue, 12 Jun 2018 12:47:03 -0500, amdx wrote:
>>
>>> A copy of my 7:03 am post.
>>>
>>> After installing 237ft of twisted speaker wire, connecting it to my
>>> 300ft Beverage On the Ground, and with an approximately 250 ohm
>>> terminating resistor. I tested a little last evening.
>>> Here's a short video of one frequency while I switch between the BOG,
>>> Longwire and Mini Whip antennas.
>>>
>>> > https://www.youtube.com/watch?v=q8rBb2v13tg
>>
>> Quite a clear demonstration of the directionality of the "BoG" which I
>> initially assumed was simply strung out on supporting poles a few feet
>> above the terrain as per the standard Beverage antenna setup.
>>
>> Can you confirm that your BoG is simply 300 foot of insulated wire laid

>> straight onto the ground with its far end terminated with a 250? non

>> inductive resistor connection to a grounding rod?
>
> It is 300ft + /- a few, the wire is army field wire like this,
> http://armysurpluswarehouse.com/wd-1a-tt-dr-8-a-telephone-cable/
> Note it is actually 2 conductor wire, but I have tied them together at
> each end. (I have thought about removing one of the wires, if I got good
> info that it would make any difference I would do it)
> I laid it on the ground as best I could, This is somewhat of a pine
> woods, so lots of pine needles and decaying vegetation on top of the dirt.
> I have 3 non inductive resistors in series (I didn't have the proper
> value) with a pot across them for the termination. I expected to make
> adjustments and test, but since I started we have had rain and lightning
> storms around, makes for tough listening.
> A 5 foot copper pipe driven in to the ground at each end.
> For the transformer I used a 35T0501-10H toroid with I think? 8 and 16
> turns. This is probably not a good design, I started with wanting to be
> able to receive 200kHz beacons, so it has more turns than needed.
> I have the recommended Material 73 binocular cores on order to make a
> better transformer.
> I don't have an ideal property, There is a a wooded area behind my house.
> I spent several days clearing brush and plants for a straight line through
> the woods. Part of it is a drainage area and gets water
> that drains through when it rains hard.
> The wire is straight, but terrain is not level, the wire follows the
> terrain.
>
>

snip.______________________

You are killing yourself by laying the antenna on the ground. Try picking it
up off the ground by 10 feet or so.

Keep the wire you have and tie both leads together on both ends as you have
done. Take the far end to ground through a few hundred ohm carbon comp (old
school) resistor. Nothing about this antenna is in any way critical.

[upsid...@downunder.com]

On Sun, 10 Jun 2018 15:35:55 -0500, amdx <noj...@knology.net> wrote:

> The antenna I'm connecting this coax to, is a BOG antenna.
>My BOG is a short 300ft "Beverage On Ground".

Are you interested in the tropical bands (60, 90, 120 meter bands) ?

For medium wave (200 to 600 m) reception, the Beverage should be at
least 600 n long,

[piglet]

On 13/06/2018 04:34, amdx wrote:
>
> Surge impedance is mentioned in the article, is this different than
> just plain impedance?
>

Surge impedance is a rather old-fashioned way of saying what we call Zo
or the transmission line characteristic impedance.

An open circuit long transmission line reads infinite ohms on a plain
'ol DC VOM but to a step (aka surge) in voltage a brief current will
flow which divided into the step voltage would equal the surge
impedance. HTH

piglet

[piglet]

On 11/06/2018 22:00, amdx wrote:
>  My conclusion, twisted speaker wire is a winner with respect to signal
> ingress.

>                                  Mikek
>

Lack of ingress could also be due to higher losses :)

Is the twisted speaker wire insulated with PVC? PVC is remarkably lossy
even at LF/MF. CAT5/6 UTP has the advantage of low loss dielectric, the
disadvantge of high resistance thin conductors can be offset by
paralleling pairs.

piglet

[amdx]

Is there a way I can measure the surge impedance of the Bog at the end
of my tested pair?
If not, how can I do this with portable home brewed test equipment at
the BOG wire start?
The only portable test equipment I have is an MFJ-259.
Thanks, Mikek

[amdx]

On 6/13/2018 3:24 AM, piglet wrote:
> On 11/06/2018 22:00, amdx wrote:
>>   My conclusion, twisted speaker wire is a winner with respect to
>> signal ingress.
>>                                   Mikek
>>
>
> Lack of ingress could also be due to higher losses :)
>

> Is the twisted speaker wire insulated with PVC? PVC is remarkably lossy
> even at LF/MF.

I'll leave this as a possibility, with the caveat that, I'm surprised at
the high signal level of the supposedly Lossy BOG antenna. The two don't
seem compatible.

CAT5/6 UTP has the advantage of low loss dielectric,

I'm working towards an antenna system with four phased antennas
using Cat5 to carry the signal and DC for amps.
I have got a mixed messages about shielded Cat5, some say grounding a
shield is no necessary others have done it.

> the disadvantge of high resistance thin conductors can be offset by
> paralleling pairs.
>

I hadn't thought about paralleling a couple pairs, that would give
approximately a 50 ohm impedance. Interesting.

Actually I did thing about paralleling, but for the DC carrying wires.
Thanks, Mikek

[piglet]

That is exactly what the MFJ-259 is built to do!

I do not have one but I think the only MFJ-259 limitations may be that
it doesn't go lower than 500kHz and that it won't read impedances higher
than 700 ohms - in all other respects you should have a great tool for
the job. I think the MFJ manual even mentions Beverage antenna somewhere?

piglet

[amdx]

OK, so surge impedance is another way to say characteristic impedance
of the cable.
I measured it a 1800kHz, (that's a low as it goes) and I get just a
little over 500ohms, but the scale is very crowded up there so It could
be 400 to 700ohms. This is with a 250 ohm termination at the end of the
wire.
I also have an LCR meter, I measured at* 120Hz, 1000Hz, 10kHz and
100kHz, got about 660 ohms on all but 100kHz then it said 12,000pf
capacitance. Again, with a 250 ohm termination at the end of the wire.

*those are the only choices

I had a time constraint, I should have looked for a resonance also,
next time.
This evening I'll add some inductance to the MFJ-259 oscillator, and
get the frequency range so I can cover 500kHz to 1700kHz, and retest.
As I know it, if I get that end termination to be the correct value
then I can adjust frequency up or down and the R measurement will stay
constant. I don't know how any impedance of the line will affect that.
That could take several 600ft trudges through the woods getting that
adjustment right. Is there a way to take several measurements at
different frequencies and calculate that.
Thanks, Mikek

Maybe I can bring out a couple of wires from the R meter on the
MFJ-259 and measure it on my digital meter. so I can see the changes.

[amdx]

I've been looking at TDR videos and one has a pulse generator
circuit. I'm not above carrying my scope out in the woods dragging an
extension cord or 3.
Mikek

[amdx]

No, I'm doing just fine, a little ache in my knee, but otherwise OK.
The antenna is good also. Do some reading on BOGs and beverages.
Here's a start, > https://tinyurl.com/yd37vtq6
I think the biggest receiving advantage is that being on the ground
reduces the VF, making the antenna seem longer than it is. It also
is less susceptible to noise.
All the info I get says it is a low signal antenna, but I only note
1 or 2 S unit difference. However last night I measured the impedance
of at the radio end of the feedline and noted about 130 ohms. S I
rewound my isolation transformer and now the long wire and BOG are about
the same. I think my BOG may have a little higher output because, It is
in a wooded area with lots of dead vegetation and pine needles, so I'm
not really directly on the dirt. I may get out and clear a line several
inches wide and see how getting it right on the dirt affects operation.
I'm still working on a way to get an actual measurement of the wires
impedance, it is to high for the MFJ-259 to measure accurately.
I did get the MFJ-259 frequency down so I can measure in the AM
broadcast band. I had to use a tapped inductor and use a switch to do
it in two steps. About 480kHz to 1Mhz and 870kHz to 2Mhz.
Mikek