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KAT 500 and open wire

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Vic Rosenthal

Re: KAT 500 and open wire

I've been using an open-wire fed rotary dipole that is a halfwave on 20
meters on all bands from 40 through 10 meters for the past 4 years or
so. The feeding/matching system has gone through various iterations, but
now uses homemade open-wire line of no. 12 wire (2 mm) spaced 4.5 inches
(11.4 cm), a very slightly modified Johnson kW Matchbox, and a pair of
inductors for reactance cancellation on 30 meters. The line is about 34
feet long (10.4 m). The SWR on the worst band (7 MHz) approaches 100:1,
but losses calculated by TLW are around 1 dB or less.

73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
On 7 Jan 2019 00:15, K9MA wrote:
> The really attractive thing about open line, and even window line, is
> that its loss is so low you can use it at a very high SWR, and take care
> of the matching at the station end. This is especially useful for
> multi-band antennas. The famous G5RV, for example, will work just
> exactly the same fed with window line and a tuner as it will with the
> usual matching section.
>
> 73,
> Scott K9MA
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Bob McGraw - K4TAX

Re: KAT 500 and open wire

In reply to this post by Charlie T, K3ICH

They are a voltage type, 4:1 designed to feed a folded dipole. There are
actually 4 windings, 2 on each coil.

If you want to see the best in balun usage and efficiency, a folded
dipole typically has some 200 to 300 ohms impedance when constructed
from open wire line or like materials.    Thus the upper radiator and
lower radiator are equal diameters. Of course it basically a single
band antenna and when used with a 4:1 balun provides, a 50 to 75 ohm
load for the transmitter.   For that reason, I believe hams {not me for
one}, have gotten away from the design. There is a lot of merit to the
folded dipole antenna, relatively broadband, less noise on receive, low
loss, high efficiency and etc.   I use one for my 160M and another for
my 75M AM stations.    Both of mine are constructed from heavy 300 ohm
transmitting feed line. One must pay special attention to end support
means {and not by the conductors with an insulator} and center support
where the feed line is attached.

73

Bob, K4TAX

On 1/6/2019 10:17 PM, Charlie T wrote:

> I should probably know this, but what is the old dual air coil Heathkit B-1
> balun, a current or voltage type?
> If I remember correctly, they are 4:1 ratio.
> Would this be a better choice for open-wire feed to a dipole intended for
> use on several bands?
>
> 73, Charlie k3ICH
>
>
>

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David Woolley (E.L)

Re: KAT 500 and open wire

In reply to this post by Jim Brown-10

Don:

1) made a distinction between feedpoint and load impedance, which led me
to believe the load was the antenna, and the feedpoint the transmitter end;

2) said that the feedpoint impedance depended on the length of the line
and the frequency, which further supported that interpretation.

However, considering your definition of feedpoint, and consider balanced
twin feeder. Even with a perfect choke at the feedpoint, there will be
unbalance at the transmitter end, when using designs, like the K series,
that feed against chassis. In particular, consider a feeder length of a
quarter wavelength. As well as the intended differential mode signal,
you will also excite the feeder as a quarter wave vertical against the
chassis and, presumably, ground, if you don't choke at the transmitter end.

My gut feeling is that having a good match to the feeder is an
oversimplification, but I need to think about that a bit more.

Incidentally, is the 4:1 "current mode" balun configuration really
purely current mode? It seems to me that it is behaving as a
transformer as well as as a choke.

On 07/01/2019 02:12, Jim Brown wrote:
> I think we're confused here about the meaning the words "feedpoint
> impedance." It is the impedance of THE ANTENNA at the point where the
> feedline is attached, and it is determined entirely by the antenna,
> INCLUDING the common mode circuit of the

> I don't know of a way to EFFECTIVELY choke a feedline that is not matched to the antenna.
> a very good choke must be AT THE FEEDPOINT

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Wes Stewart-2

Re: KAT 500 and open wire

In reply to this post by Bob McGraw - K4TAX

Then there must be less signal too:-)

Wes N7WS

On 1/7/2019 6:48 AM, Bob McGraw K4TAX wrote:

> ... less noise on receive...
>
> 73
>
> Bob, K4TAX

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Wes Stewart-2

Re: KAT 500 and open wire

In reply to this post by K9MA

With all due respect, you don't say what acceptable loss is. Of course, you can
match whatever the impedance is, most tuners will match an open circuit because
their internal losses allow it. But it can be a fallacy that, "The line loss is
so low it doesn't matter." Absent voltage breakdown, line loss increases
because of the increased circulating current resulting from operating at
elevated SWR. That increased current is an issue in some baluns and tuners as
well. *All* of these components must be considered when evaluating an antenna
"system." Considering only one part in isolation is fraught with danger.

Try running that 102' long "G5RV" up 50' on 160 meters. Feed it with 100' of
Wireman 553 "low loss" ladderline. The 0.1 dB matched loss turns into over 13
db at the input and that's without considering tuner loss. (Source: EZNEC and
TLDetails)

Wes N7WS

On 1/6/2019 3:15 PM, K9MA wrote:
> The really attractive thing about open line, and even window line, is that its
> loss is so low you can use it at a very high SWR, and take care of the
> matching at the station end. This is especially useful for multi-band
> antennas. The famous G5RV, for example, will work just exactly the same fed
> with window line and a tuner as it will with the usual matching section.
>
> 73,
> Scott K9MA

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Don Wilhelm

Re: KAT 500 and open wire

There is a BIG difference between ladder line and open wire transmission
line.

Even low loss ladder line can have significant loss, especially when wet.

Open wire feeders can truly be low loss even when operated at high SWR.

So how do you construct proper open wire line? It is most easily done
when the 2 wires are under tension and spaced about 6 inches apart with
as few insulators between them as possible - the tension keeps the
spacing relatively constant - that is practical over a long horizontal
run of the transmission line. Then bring it up to the antenna feedpoint
with wires spaced apart with insulators, and likewise on the run to the
house entry or better yet to the shack - the more insulators, the
greater the loss can be. You can use ladder-line from there into the
shack, or you can put a good current mode balun at the house entry and
from there run a short length of coax to the tuner.

As I have mentioned before, whether a 1:1 balun or a 4:1 balun will work
better has to be determined - it depends on the feedline length, the
frequency, and the feedpoint impedance of the radiator for that
particular frequency. If the feedpoint impedance at the tuner end of
the feedline is already low, a 4:1 balun will make it 4 times lower and
difficult for your tuner to deal with.

A G5RV antenna on 160 meters will not be very efficient (the high
current point will be somewhere down the transmission line and not at
the center of the antenna). One thing is true, the RF voltage at the
ends of the antenna is the highest, and the highest current is 1/4
wavelength away from the end, even if that is at a point well down the
feedline. The equal and opposite currents on the feedline will cancle
making that highest current point not useful for radiating a signal.

Radiator lengths greater than 1/2 wavelength can be efficient, but
shorter than 1/2 wavelength will be less efficient because the balanced
currents on the feedline cancel each other out. That is just plain physics.

73,
Don W3FPR

On 1/7/2019 10:49 AM, Wes Stewart wrote:
>
>
> Try running that 102' long "G5RV" up 50' on 160 meters. Feed it with
> 100' of Wireman 553 "low loss" ladderline. The 0.1 dB matched loss
> turns into over 13 db at the input and that's without considering tuner
> loss. (Source: EZNEC and TLDetails)
>
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K9MA

Re: KAT 500 and open wire

In reply to this post by Wes Stewart-2

There are limits, of course, as your example shows. A center fed quarter
wave is a very low impedance. I'd expect the feedline loss for that G5RV
system would be less than a couple dB on 80 through 10 meters, generally
acceptable.

73,
Scott K9MA

On 1/7/2019 09:49, Wes Stewart wrote:

>
> With all due respect, you don't say what acceptable loss is. Of
> course, you can match whatever the impedance is, most tuners will
> match an open circuit because their internal losses allow it. But it
> can be a fallacy that, "The line loss is so low it doesn't matter."
> Absent voltage breakdown, line loss increases because of the increased
> circulating current resulting from operating at elevated SWR. That
> increased current is an issue in some baluns and tuners as well.
> *All* of these components must be considered when evaluating an
> antenna "system." Considering only one part in isolation is fraught
> with danger.
>
> Try running that 102' long "G5RV" up 50' on 160 meters. Feed it with
> 100' of Wireman 553 "low loss" ladderline. The 0.1 dB matched loss
> turns into over 13 db at the input and that's without considering
> tuner loss. (Source: EZNEC and TLDetails)
>
> Wes N7WS
>
> On 1/6/2019 3:15 PM, K9MA wrote:
>> The really attractive thing about open line, and even window line, is
>> that its loss is so low you can use it at a very high SWR, and take
>> care of the matching at the station end. This is especially useful
>> for multi-band antennas. The famous G5RV, for example, will work just
>> exactly the same fed with window line and a tuner as it will with the
>> usual matching section.
>>
>> 73,
>> Scott K9MA
>
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--
Scott K9MA

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K9MA

Re: KAT 500 and open wire

In reply to this post by Don Wilhelm

On 1/7/2019 10:39, Don Wilhelm wrote:
> Radiator lengths greater than 1/2 wavelength can be efficient, but
> shorter than 1/2 wavelength will be less efficient because the
> balanced currents on the feedline cancel each other out. That is just
> plain physics.

Actually, a short antenna CAN be very efficient, as long as the
resistance of the antenna itself is low and the losses in the matching
network are low. I didn't say it was easy, though.

73,

Scott K9MA

--
Scott K9MA

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Elecraft mailing list

Re: KAT 500 and open wire

In reply to this post by Viggo Magnus Nilsen Nilsen

Re: "...what is the old dual air coil Heathkit B-1balun, a current or voltage type? If I remember correctly, they are 4:1 ratio."

From the Heathkit manual: "The Heathkit Balun Coil Set, Model B-1 is a convenient transmitter accessory which has the capability of matching unbalanced coax lines, used on most modern transmitters, to balanced lines to either 75 ohms or 300 ohms impedance".

The manual discusses its use with a dipole (~75 ohms) or a folded dipole (~300 ohms), and the analogy of using a line transmission line to get the desired impedance transformation. It is a very short but interesting read.

The assembly manual shows how to wire it in 1:1 or 4:1 configurations. The schematic is identical to the Elecraft BL2 , except it uses air core coils instead of ferrite coils, and there is no switch to easily change between impedance ratios.

I have never used my BL-2, so I cannot vouch for its effectiveness. I have often wondered if it might be compromised by the 2 bifilar wound "non-self-shielding" air core coils tightly packed into a metal enclosure resulting in enough capacitance or magnetic coupling to each other and the enclosure to reduce its effectiveness.

I do, however, open it up occasionally and admire those beautiful inductors!

Mark
KE6BB

null
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Jim Brown-10

Re: KAT 500 and open wire

In reply to this post by Don Wilhelm

On 1/7/2019 8:39 AM, Don Wilhelm wrote:
> Even low loss ladder line can have significant loss, especially when wet.

N7WS is the guy who did that research and published it several decades
ago. It's in one of those excellent ARRL Antenna Compendiums.

73, Jim K9YC

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Bob McGraw - K4TAX

Re: KAT 500 and open wire

In reply to this post by Don Wilhelm

I use the "window line" for 3 of my antennas. We have less than 125 days/ yr with precipitation of all types. The "loss wet" is a non issue in my thinking as I'm sure would be about the same for most folks.

Still with extreme loss, under most conditions, coax will have greater loss.

Bob, K4TAX

Sent from my iPhone

> On Jan 7, 2019, at 11:34 AM, Walter Underwood <[hidden email]> wrote:
>
> I think “window line” is less ambiguous for the stuff separated by plastic with squares cut out. I see “ladder line” being used to mean either window line or open wire line.
>
> DX Engineering uses ladder line to mean the plastic dielectric line: https://www.dxengineering.com/search/part-type/ladder-line
>
> W7FG uses ladder line to mean 600 Ohm open wire line: http://trueladderline.com/w7fg-design-600-ohm-open-wire-feedline/
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
>> On Jan 7, 2019, at 8:39 AM, Don Wilhelm <[hidden email]> wrote:
>>
>> There is a BIG difference between ladder line and open wire transmission line.
>>
>> Even low loss ladder line can have significant loss, especially when wet.
>>
>> Open wire feeders can truly be low loss even when operated at high SWR.
>>
>> So how do you construct proper open wire line? It is most easily done when the 2 wires are under tension and spaced about 6 inches apart with as few insulators between them as possible - the tension keeps the spacing relatively constant - that is practical over a long horizontal run of the transmission line. Then bring it up to the antenna feedpoint with wires spaced apart with insulators, and likewise on the run to the house entry or better yet to the shack - the more insulators, the greater the loss can be. You can use ladder-line from there into the shack, or you can put a good current mode balun at the house entry and from there run a short length of coax to the tuner.
>>
>> As I have mentioned before, whether a 1:1 balun or a 4:1 balun will work better has to be determined - it depends on the feedline length, the frequency, and the feedpoint impedance of the radiator for that particular frequency. If the feedpoint impedance at the tuner end of the feedline is already low, a 4:1 balun will make it 4 times lower and difficult for your tuner to deal with.
>>
>> A G5RV antenna on 160 meters will not be very efficient (the high current point will be somewhere down the transmission line and not at the center of the antenna). One thing is true, the RF voltage at the ends of the antenna is the highest, and the highest current is 1/4 wavelength away from the end, even if that is at a point well down the feedline. The equal and opposite currents on the feedline will cancle making that highest current point not useful for radiating a signal.
>>
>> Radiator lengths greater than 1/2 wavelength can be efficient, but shorter than 1/2 wavelength will be less efficient because the balanced currents on the feedline cancel each other out. That is just plain physics.
>>
>> 73,
>> Don W3FPR
>>
>>
>>
>>> On 1/7/2019 10:49 AM, Wes Stewart wrote:
>>> Try running that 102' long "G5RV" up 50' on 160 meters. Feed it with 100' of Wireman 553 "low loss" ladderline. The 0.1 dB matched loss turns into over 13 db at the input and that's without considering tuner loss. (Source: EZNEC and TLDetails)
>> ______________________________________________________________
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Eric Swartz - WA6HHQ

Re: KAT 500 and open wire

Administrator

In reply to this post by Wes Stewart-2

Guys - we've long since passed he max posting limit for the list on a single
topic. Let's wind this one down at this time.

73,
Eric
/Moderator (hopefully not for life!..)/
/elecraft.com/

On 1/7/2019 7:45 AM, Wes Stewart wrote:
> Then there must be less signal too:-)
> Wes N7WS
>
> On 1/7/2019 6:48 AM, Bob McGraw K4TAX wrote:
>
>> ... less noise on receive...
>> 73
>> Bob, K4TAX
>

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alorona

Re: KAT 500 and open wire

In reply to this post by Jim Brown-10

G3TXQ's work here is awesome, as is N7WS's before him. I'm thinking two things:

Thing 1 is that, clearly, water really messes up window line's loss. However, I'm guessing that a/ in a place like southern California, where perpetual drought is the new normal; and b/ in an installation where the window line, rather than running perfectly horizontally so water can pool, has a slant, allowing it to shed water; a ham would probably be fine using it. All one would have to do to discourage pooling on a horizontal run is twist the line once every few meters.

Thing 2 is that G3TXQ shows matched loss at 6.72 MHz in heavy rainfall increasing from 0.2 to 1.1 dB per 100 feet, which seems totally acceptable for worst-case rainfall. In moderate rainfall the loss increased to only 0.34 dB/100 ft. That's lower than any coax out there.

I myself would never use it (for reasons other than water loss), but window line seems like an okay choice for those hams who can't or won't use coax.

Al W6LX

Glossary:

"Window line" = Wireman 551 or 552 or equivalent

>>> http://www.karinya.net/g3txq/wet_ll/

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Bob McGraw - K4TAX

Re: KAT 500 and open wire

Using matching transformers and my spectrum analyzer with tracking
generator, I measured a 100 ft length dry and I measured it wet. My
measurements indicated the velocity factor changed when wet, i.e. the
electrical length of the line changed. Thus explains to me the reason
to "retune" when the line is wet or covered with frost, ice or snow.
With my tuner, that means I must push a button. Oh geezzzzz.

I agree the loss does increase a wee bit when wet in a horizontal
position. Considering we have less than 100 days with recorded or
measured precipitation in my area, it is no big deal. My window line is
mostly vertical and that which is horizontal has about 5 twists per 10
ft. Still worst case, I find it has less loss than coax and less
expensive than coax which has equal or less loss.

73

Bob, K4TAX

On 1/18/2019 8:08 PM, Al Lorona wrote:

> G3TXQ's work here is awesome, as is N7WS's before him. I'm thinking two things:
>
> Thing 1 is that, clearly, water really messes up window line's loss. However, I'm guessing that a/ in a place like southern California, where perpetual drought is the new normal; and b/ in an installation where the window line, rather than running perfectly horizontally so water can pool, has a slant, allowing it to shed water; a ham would probably be fine using it. All one would have to do to discourage pooling on a horizontal run is twist the line once every few meters.
>
> Thing 2 is that G3TXQ shows matched loss at 6.72 MHz in heavy rainfall increasing from 0.2 to 1.1 dB per 100 feet, which seems totally acceptable for worst-case rainfall. In moderate rainfall the loss increased to only 0.34 dB/100 ft. That's lower than any coax out there.
>
> I myself would never use it (for reasons other than water loss), but window line seems like an okay choice for those hams who can't or won't use coax.
>
> Al W6LX
>
>
> Glossary:
>
> "Window line" = Wireman 551 or 552 or equivalent
>
>
>
>>>> http://www.karinya.net/g3txq/wet_ll/
>
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Bob McGraw - K4TAX

Re: KAT 500 and open wire

In reply to this post by alorona

I didn't measure significant increase in loss with clean water i.e. tap
water sprayed on the entire length of the line from a hose. I did make
a solution of dish washing detergent and water and , using a spray
bottle, sprayed that on the line. This caused much more water to cling
to the line. While the loss did not appreciably increase, I did notice
the electrical length of the line changed a measurable amount.
Measurements were made such that the line was operating at its
characteristic impedance. The source was the tracking generator in my
Spectrum Analyzer, sweeping 1 MHz to 50 MHz.

73

Bob, K4TAX

On 1/18/2019 11:56 PM, Walter Underwood wrote:

>> On Jan 18, 2019, at 6:08 PM, Al Lorona <[hidden email]> wrote:
>>
>> Thing 1 is that, clearly, water really messes up window line's loss. However, I'm guessing that a/ in a place like southern California, where perpetual drought is the new normal; ...
> Clean water isn’t a problem. Dirty water is a big problem.
>
> When I first moved to the SF Bay area in the early 1980s, I was surprised by the number of power outages, compared to where I grew up in Louisiana with heavy weather. The first light rain would be accompanied by outages. With six or more rainless summer months, dust and grit would accumulate on the power line insulators. The first light rain would create conductive mud and trip breakers. So perpetual drought is just a way to build up more dust on the line.
>
> I think we take coaxial cable for granted. It was a brilliant invention and a real gift to people who love radio. Maybe I’ll start celebrating December 8th as Coaxial Cable Day.
>
> https://www.wired.com/2009/12/1208coaxial-cable-patent/
>
> wunder
> K6WRU
> Walter Underwood
> CM87wj
> http://observer.wunderwood.org/ (my blog)
>
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Vic Rosenthal

Re: KAT 500 and open wire

When I used to use ladder line I noticed a significant detuning effect
when wet. It was worse with older line, probably because the weathering
made the water more likely to stick. I never tried to measure the loss.

I tried waxing the line with automotive wax and saw an improvement. But
I don't know how long it would have lasted, since I switched to other
feedlines.

Today I'm using homemade open wire line, no. 12 (2 mm dia) spaced 4.5
inches (11.4 cm). Insulators are cut from black irrigation hose. Wire is
ultra flexible type from The Wireman.

It works great with no noticeable weather effects. It's very easy to
make: I made a jig from a piece of tubing to cut the insulators to the
same length. The jig has holes to drill near the ends of the insulators;
then I snipped a cut from the edge to the hole to enable the wire to
snap in. The holes are just big enough to grip the wire but to let me
slip the insulators a bit to get them in the right place. In a few
locations I made insulators out of fiberglass that could be attached to
brackets to hold the line in place.

73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
On 19 Jan 2019 16:45, Bob McGraw K4TAX wrote:

> I didn't measure significant increase in loss with clean water i.e. tap
> water sprayed on the entire length of the line from a hose. I did make
> a solution of dish washing detergent and water and , using a spray
> bottle, sprayed that on the line. This caused much more water to cling
> to the line. While the loss did not appreciably increase, I did notice
> the electrical length of the line changed a measurable amount.
> Measurements were made such that the line was operating at its
> characteristic impedance. The source was the tracking generator in my
> Spectrum Analyzer, sweeping 1 MHz to 50 MHz.
>
> 73
>
> Bob, K4TAX
>
>
> On 1/18/2019 11:56 PM, Walter Underwood wrote:
>>> On Jan 18, 2019, at 6:08 PM, Al Lorona <[hidden email]> wrote:
>>>
>>> Thing 1 is that, clearly, water really messes up window line's loss.
>>> However, I'm guessing that a/ in a place like southern California,
>>> where perpetual drought is the new normal; ...
>> Clean water isn’t a problem. Dirty water is a big problem.
>>
>> When I first moved to the SF Bay area in the early 1980s, I was
>> surprised by the number of power outages, compared to where I grew up
>> in Louisiana with heavy weather. The first light rain would be
>> accompanied by outages. With six or more rainless summer months, dust
>> and grit would accumulate on the power line insulators. The first
>> light rain would create conductive mud and trip breakers. So perpetual
>> drought is just a way to build up more dust on the line.
>>
>> I think we take coaxial cable for granted. It was a brilliant
>> invention and a real gift to people who love radio. Maybe I’ll start
>> celebrating December 8th as Coaxial Cable Day.
>>
>> https://www.wired.com/2009/12/1208coaxial-cable-patent/
>>
>> wunder
>> K6WRU
>> Walter Underwood
>> CM87wj
>> http://observer.wunderwood.org/ (my blog)
>>
>> ______________________________________________________________
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>>
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>
> ______________________________________________________________
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Bill K9YEQ

Re: KAT 500 and open wire

In reply to this post by alorona

You can buy spacers for #14 insulated house wire that would also work wonders and be a cheaper but best solution.

73,
Bill
K9YEQ

https://wrj-tech.com/

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Al Lorona
Sent: Friday, January 18, 2019 8:08 PM
To: Elecraft <[hidden email]>
Subject: Re: [Elecraft] KAT 500 and open wire

G3TXQ's work here is awesome, as is N7WS's before him. I'm thinking two things:

Thing 1 is that, clearly, water really messes up window line's loss. However, I'm guessing that a/ in a place like southern California, where perpetual drought is the new normal; and b/ in an installation where the window line, rather than running perfectly horizontally so water can pool, has a slant, allowing it to shed water; a ham would probably be fine using it. All one would have to do to discourage pooling on a horizontal run is twist the line once every few meters.

Thing 2 is that G3TXQ shows matched loss at 6.72 MHz in heavy rainfall increasing from 0.2 to 1.1 dB per 100 feet, which seems totally acceptable for worst-case rainfall. In moderate rainfall the loss increased to only 0.34 dB/100 ft. That's lower than any coax out there.

I myself would never use it (for reasons other than water loss), but window line seems like an okay choice for those hams who can't or won't use coax.

Al W6LX

Glossary:

"Window line" = Wireman 551 or 552 or equivalent

>>> http://www.karinya.net/g3txq/wet_ll/

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k6dgw

Re: KAT 500 and open wire

In reply to this post by Vic Rosenthal

Be careful with black hose/tubing/pipe. Cut a small length of it and
put it into a microwave oven along with a cup of water for varying
lengths of time, checking each time. If it comes out cool when the
water is about to boil, it's probably OK. It seems some ABS and black
drip tubing has some semi-conductive ingredient(s) like carbon? I've
also seen white PVC fittings that failed this test.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 1/19/2019 7:45 AM, Victor Rosenthal 4X6GP wrote:

> Today I'm using homemade open wire line, no. 12 (2 mm dia) spaced 4.5
> inches (11.4 cm). Insulators are cut from black irrigation hose. Wire
> is ultra flexible type from The Wireman.
>
> 73,
> Victor, 4X6GP
> Rehovot, Israel
> Formerly K2VCO
> CWops no. 5
> http://www.qsl.net/k2vco/

Brian Hunt

Re: KAT 500 and open wire

In reply to this post by Bill K9YEQ

Electric fence insulator tubes 4" long. Drill each end for #14 THHN stranded. 3.5" spacing gives Zo= ~550 ohms. Box of 200 on Amazon for $16.

73,
K0DTJ
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