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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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
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
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
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
> On Jan 18, 2019, at 6:08 PM, Al Lorona 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
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
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
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
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,
A pre-publication copy of the N7WS QST article from 1999.
http://k6mhe.com/n7ws/Ladder_Line.pdf
Independent verification of the N7WS experiments, with some nice graphs showing
loss when dry, with rainwater, and with frost. The results are fairly similar.
http://www.karinya.net/g3txq/wet_ll/
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
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
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:
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
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
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
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
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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Help:
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
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.
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
, 2019 10:24 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KAT 500 and open wire
On 1/6/2019 20:12, Jim Brown wrote:
We add one or more common mode chokes to minimize the effect if the
common mode circuit, which is radiation and reception, and to do that,
a very good choke must
-
From: elecraft-boun...@mailman.qth.net On
Behalf Of K9MA
Sent: Sunday, January 06, 2019 10:24 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KAT 500 and open wire
On 1/6/2019 20:12, Jim Brown wrote:
> We add one or more common mode chokes to minimize the effect if the
> commo
On 1/6/2019 20:12, Jim Brown wrote:
We add one or more common mode chokes to minimize the effect if the
common mode circuit, which is radiation and reception, and to do that,
a very good choke must be AT THE FEEDPOINT. I don't know of a way to
EFFECTIVELY choke a feedline that is not matched
I agree with Jim on this point. I have means to measure current in
each side of the balanced feed line. And I have means to measure the
voltage on each leg and observe the phase difference in each leg. A
dual trace scope with 2 current probes is the basic configuration. If
the currents
I agree with Jim on this point. I have means to measure current in
each side of the balanced feed line. And I have means to measure the
voltage on each leg and observe the phase difference in each leg. A
dual trace scope with 2 current probes is the basic configuration. If
the currents
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 feedline. That common mode
circuit consists of
The feedpoint impedance DOES depend on the characteristic impedance!
Taking pure resistive cases (real characteristic impedances aren't), and
lossless lines, a 75 ohm load at the end of a 75 ohm transmission line
will have a feed point impedance that is a constant 75 ohms, whereas a
75 ohm
Don,
I guess I should have pointed out that I was assuming one of those
wide-range, balanced tuners of days of yore. I have one of those
plug-in coil tuners I built long ago, and it will match almost anything,
so feedline length is seldom an issue. Alas, the commercial tuners
available
I learned a lot about my low band antenna system by building a full model of it
using EZNEC and SimSmith. It enabled me to learn where the losses were band by
band and resulted in a few changes. On 80m SimSmith said the loss in the 450
ohm was high because of the specific type I was using. It
Scott,
As I indicated, that is NOT true of just any length of window line.
Some will work while others will not.
With the G5RV, the only thing we know for sure is that on 20 meters, the
impedance at the end of 34 feet of 300 ohm feedline is approximately 75
ohms.
The impedance at that point
In the case of SWBC the matching happens at the TX.
Sent from my iPad
> On Jan 6, 2019, at 5:15 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
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
Well said, Don!
73,
Scott K9MA
On 1/6/2019 15:40, Don Wilhelm wrote:
All,
I think a bit of extended study on transmission lines and their
impedance transformation characteristics is in order - refer to any
ARRL antenna book, even those from the 1950 an 1960 era, not much new
has been
And those broadcast stations generally work within a 2:1 VSWR range.
Sent from my iPad
> On Jan 6, 2019, at 4:51 PM, Bob McGraw K4TAX wrote:
>
> Correct on all points.
>
> That is the reason I gave my feedline type, and length and antenna length
> alone with specific balun type and common
Correct on all points.
That is the reason I gave my feedline type, and length and antenna
length alone with specific balun type and common mode choke type. Any
old ragged combination of chunks of wire and feed line is not assured to
work and is largely the reason many hams shy away from
All,
I think a bit of extended study on transmission lines and their
impedance transformation characteristics is in order - refer to any ARRL
antenna book, even those from the 1950 an 1960 era, not much new has
been added, other than baluns. The feedpoint impedance to the
transmission line
Using a balun with balanced line is risky. Window line or open line can
be used with reasonable losses up to at least a 10:1 SWR, but that means
the impedance at the balun output could be anywhere from 30 to 3000 Ohms
(for 300 Ohm line). The current balun should work if the impedance at
the
Yes I use a balanced feed line being the "window" type line. It feeds
a 250 ft wire in the center at 50 feet. I have about 75 ft of feed line
from the center of the antenna then, through the attic eve vent,
supported on some wooden hangers I made and attached to the roof
rafters. Then it
Yes Viggo I use an open wire CF Zepp via a 4:1 balun with my KAT500. It
works great. (:-))
73
K0PP
On Sun, Jan 6, 2019, 10:01 Viggo Magnus Nilsen Nilsen Hello Elecrafters,
>
> Do some of you using KAT500 with open wire,ladder line feed to ur wire
> antennas with balun (outside the tuner) ?
Hello Elecrafters,
Do some of you using KAT500 with open wire,ladder line feed to ur wire
antennas with balun (outside the tuner) ? working ok ?
73' LA9NEA Viggo M.
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