Source For 72 or 75 Ohm Ladder Line ???
 

Had an E-Mail as to where to buy ladder line -- 72 or 75 ohm for antenna
feeder

Understand it is scarce in the USA but may be available in the UK

Sources anyone? thanks
--
One Watt

To steal ideas from one person is plagiarism;
to steal from many is research.
-- Comedian Steven Wright

zip cord
"Micro MegaWatt" wrote in message
news:uvHWc.131575$sh.83524@fed1read06...
Had an E-Mail as to where to buy ladder line -- 72 or 75 ohm for antenna
feeder

Understand it is scarce in the USA but may be available in the UK

Sources anyone? thanks
--
One Watt

To steal ideas from one person is plagiarism;
to steal from many is research.
-- Comedian Steven Wright

"H. Adam Stevens, NQ5H" wrote in message
...
zip cord
...
Had an E-Mail as to where to buy ladder line -- 72 or 75 ohm for antenna
feeder

Understand it is scarce in the USA but may be available in the UK

Sources anyone? thanks
--
One Watt

To steal ideas from one person is plagiarism;
to steal from many is research.
-- Comedian Steven Wright


I think if you do the math, any benefit of using balanced 75 Ohm line-
especially zip cord with a lossy vinyl dielectric will be lost- especially
if not running at low VSWR conditions.
My impressiion is that ladder line or balanced line is advantageous when the
line is run at a high VSWR. The low matched loss then also means a low loss
when run at high VSWR.

Dale W4OP

There's no such things as 72 or 75 ohm ladder line.

Ladder-line wires are spaced much too far apart and have mostly air
insulation. They have impedances from 300 ohms and upwards.

Expect to find very low impedances only with twin-wires embedded in a thick,
circular or elliptical PVC sheath. Loss per unit length is quite high and
suitable only for directly feeding, resonant, single-band, 1/2-wave dipoles
at the lower frequencies.

Zip-cord and twin speaker cables have Zo between 120 and 135 ohms. 16 to
20-gauge, colourless, speaker cables make a fair compromise between
impedance, loss, SWR and small size. And exact impedance values are never
critical at HF.
---
Reg, G4FGQ

Had an E-Mail as to where to buy ladder line -- 72 or 75 ohm for antenna
feeder

out of curiosity - why ?



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On Tue, 24 Aug 2004 06:36:26 -0700, "Micro MegaWatt"
wrote:

Had an E-Mail as to where to buy ladder line -- 72 or 75 ohm for antenna
feeder

Getting a _balanced_ feeder at such low impedance levels is quite
challenging, since a typical twisted pair (e.g.CAT5) would be in the
100-120 ohm range.

You _might_ get something in the balanced 50-75 ohm range by getting a
quad-pair cable and connecting the diagonally opposite conductors
together. Thus, if the original pair had an impedance of 140-150 ohms,
the two pars in the quad-pair cable would give 70-75 ohms.

Paul OH3LWR

Beldin 8210, I believe discontinued, was/is 75 ohm twin lead; and, it
was quite popular 30+ years ago.

I haven't seen it in years. Last usage was in the 1950s on a 40 meter
dipole connecting to a pair of 807s in P-P with a Shielded Faraday link
to keep the TVI down.

Does this bring back memories among the 'old timers'?

W1MCE 50 years.

Micro MegaWatt wrote:

Had an E-Mail as to where to buy ladder line -- 72 or 75 ohm for antenna
feeder

Understand it is scarce in the USA but may be available in the UK

Sources anyone? thanks
--
One Watt

To steal ideas from one person is plagiarism;
to steal from many is research.
-- Comedian Steven Wright

"Micro MegaWatt" wrote in message
news:uvHWc.131575$sh.83524@fed1read06...
Had an E-Mail as to where to buy ladder line -- 72 or 75 ohm for antenna
feeder

Understand it is scarce in the USA but may be available in the UK

Sources anyone? thanks
--
One Watt


It may not be an answer to your question, but, 4 lengths of 75 ohm coax
connected in series and parallel would result in 75 ohms, balanced. Two 50
ohm coax cables "paralleled" could provide 100 ohms balanced with the center
conductors used as the balanced line.

Jerry

450 ohm is often preferred for multiband antennas. But 72 ohm is available in
the US, can't remember if Davis RF, RadioWorks, or who that carries it.

On 25 Aug 2004 01:03:32 GMT, (K9SQG) wrote:

450 ohm is often preferred for multiband antennas. But 72 ohm is available in
the US, can't remember if Davis RF, RadioWorks, or who that carries it.

None of the usual suppliers carry anything but 300 & 450 ohm line
nowadays. I suspect the 75 ohm isn't made anymore -- it's pictured in
my 1985 arrl handbook, but nothing more recent. (The stuff is real
skinny -- about like zipcord.)

bob
k5qwg