Hal Rosser wrote:
Have fun - use twin-lead 300-ohm or ladder-line 450ohm...
use a half-wave u-shape balun + a 1/4-wave stub on each end - and your runs
can be pretty long without a lot of loss - or a lot of expense.


I'm afraid this is largely a myth from the Olden Days. Back then,
twin-lead was probably better than most types of coax that hams could
buy... but coax has improved, and twin-lead hasn't.

The myth has been overly influenced by a few measurements dating back to
the 1950s, made under ideal conditions that can't be achieved in real
installations.

The reality is that twin-lead is difficult to install, sensitive to
electrical disturbances, of very poor quality if it's also low-cost, and
*very* sensitive to getting wet. The higher in frequency you go, the
more each one of these things matters.

(Yes, I know there are a billion TV sets out there using twin-lead - but
that doesn't make it right. Most viewers in the USA have been
brainwashed to accept appalling standards of TV picture quality.)

Parallel-line can be excellent for power distribution and phasing
*within* a stacked array. I've used it on the moonbounce array at
432MHz, in a wet climate, but those were short, straight lines that are
self-supporting with mostly air insulation - a completely different
thing.



"Rob" wrote in message
m...
I am finally going to put up a VHF antenna for 2 meter and another antenna
for 70 cm.

What is type of coax should I use? Rg213? Or will RG213 be too lossy?

Recommendations please...

As many others have said, it depends how important low loss will be for
*your* particular application.

If a significant length is involved, and you're interested in weak
signals, then RG213 (full quality, no substitutes) should be your
minimum specification.

People in the USA can recommend specific brands that will be available
to you.



--
73 from Ian G3SEK
'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek

Ian White, G3SEK wrote:
Parallel-line can be excellent for power distribution and phasing
*within* a stacked array. I've used it on the moonbounce array at
432MHz, in a wet climate, but those were short, straight lines that are
self-supporting with mostly air insulation - a completely different thing.

Given a single dipole, multi-band antenna, parallel transmission line
is just about the only choice. The 50 ohm SWR on a one-wavelength
dipole is about 100:1. The 500 ohm SWR on a one-wavelength dipole is
about 10:1. Under those circumstances, it is no contest.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:
Parallel-line can be excellent for power distribution and phasing
*within* a stacked array. I've used it on the moonbounce array at
432MHz, in a wet climate, but those were short, straight lines that
are self-supporting with mostly air insulation - a completely
different thing.

Given a single dipole, multi-band antenna, parallel transmission line
is just about the only choice. The 50 ohm SWR on a one-wavelength
dipole is about 100:1. The 500 ohm SWR on a one-wavelength dipole is
about 10:1. Under those circumstances, it is no contest.

Very true... but also a *very* long way from the original question.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Ian White, G3SEK wrote:
Cecil Moore wrote:
Given a single dipole, multi-band antenna, parallel transmission line
is just about the only choice. The 50 ohm SWR on a one-wavelength
dipole is about 100:1. The 500 ohm SWR on a one-wavelength dipole is
about 10:1. Under those circumstances, it is no contest.

Very true... but also a *very* long way from the original question.

Too bad English is not a context-free language, huh?
--
73, Cecil http://www.qsl.net/w5dxp



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I respect your opinion, but the question did not say 'multiband' antenna.
I used belden 300-ohm twinlead for 2-meters because I had a long run to the
top of a tree on the other side of the yard. The specs showed it to be
low-loss at 2-meters. The cost was affordable - much less than low-loss
coax.
So I used a u-bent half-wave piece of coax on each end and a 1/4-wave of
75-ohm coax with it - and it performed very well in the real world and the
impedence match was good.
I even had the project published in the Antenna Compendium a few yrs back.

"Cecil Moore" wrote in message
...
Ian White, G3SEK wrote:
Parallel-line can be excellent for power distribution and phasing
*within* a stacked array. I've used it on the moonbounce array at
432MHz, in a wet climate, but those were short, straight lines that are
self-supporting with mostly air insulation - a completely different
thing.

Given a single dipole, multi-band antenna, parallel transmission line
is just about the only choice. The 50 ohm SWR on a one-wavelength
dipole is about 100:1. The 500 ohm SWR on a one-wavelength dipole is
about 10:1. Under those circumstances, it is no contest.
--
73, Cecil http://www.qsl.net/w5dxp



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I've used it with success - recently. 450-ohm window-line (has copper-clad
steel conductors, so its tuff)
then on each end: a combination to match impedence - a 75-ohm 1/4-wave stub
(goes from 50 to 112.5 ohm) then a half-wave u-bent setup (112.5 to 450 ohm)
see page 165 of Antenna Compendium vol 6 for a better description - I wrote
that article back in 1999 or so.
I've also used similar setups and 300-ohm belden twinlead.
It may be a myth from the olden days, but 2+2 still equals 4 - just like the
old days. And its not a myth - it really does work.

Hal
w4pmj

"Ian White, G3SEK" wrote in message
...
Hal Rosser wrote:
Have fun - use twin-lead 300-ohm or ladder-line 450ohm...
use a half-wave u-shape balun + a 1/4-wave stub on each end - and your
runs
can be pretty long without a lot of loss - or a lot of expense.


I'm afraid this is largely a myth from the Olden Days. Back then,
twin-lead was probably better than most types of coax that hams could
buy... but coax has improved, and twin-lead hasn't.

The myth has been overly influenced by a few measurements dating back to
the 1950s, made under ideal conditions that can't be achieved in real
installations.

The reality is that twin-lead is difficult to install, sensitive to
electrical disturbances, of very poor quality if it's also low-cost, and
*very* sensitive to getting wet. The higher in frequency you go, the
more each one of these things matters.

(Yes, I know there are a billion TV sets out there using twin-lead - but
that doesn't make it right. Most viewers in the USA have been
brainwashed to accept appalling standards of TV picture quality.)

Parallel-line can be excellent for power distribution and phasing
*within* a stacked array. I've used it on the moonbounce array at
432MHz, in a wet climate, but those were short, straight lines that are
self-supporting with mostly air insulation - a completely different
thing.



"Rob" wrote in message
m...
I am finally going to put up a VHF antenna for 2 meter and another
antenna
for 70 cm.

What is type of coax should I use? Rg213? Or will RG213 be too
lossy?

Recommendations please...

As many others have said, it depends how important low loss will be for
*your* particular application.

If a significant length is involved, and you're interested in weak
signals, then RG213 (full quality, no substitutes) should be your
minimum specification.

People in the USA can recommend specific brands that will be available
to you.



--
73 from Ian G3SEK
'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.690 / Virus Database: 451 - Release Date: 5/22/2004

Hal Rosser wrote:
I've used it with success - recently. 450-ohm window-line (has
copper-clad steel conductors, so its tuff) then on each end: a
combination to match impedence - a 75-ohm 1/4-wave stub (goes from 50
to 112.5 ohm) then a half-wave u-bent setup (112.5 to 450 ohm) see page
165 of Antenna Compendium vol 6 for a better description - I wrote that
article back in 1999 or so. I've also used similar setups and 300-ohm
belden twinlead. It may be a myth from the olden days, but 2+2 still
equals 4 - just like the old days. And its not a myth - it really does work.

What frequency? What length? What loss did you measure? Was it raining?

Of course twin-lead can "work" in a wide range of applications.

The myth is that it can beat a modern coax cable at VHF, on a long run
with practical installation difficulties, and in the rain.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

"Ian White, G3SEK" wrote in message
...
Hal Rosser wrote:
I've used it with success - recently. 450-ohm window-line (has
copper-clad steel conductors, so its tuff) then on each end: a
combination to match impedence - a 75-ohm 1/4-wave stub (goes from 50
to 112.5 ohm) then a half-wave u-bent setup (112.5 to 450 ohm) see page
165 of Antenna Compendium vol 6 for a better description - I wrote that
article back in 1999 or so. I've also used similar setups and 300-ohm
belden twinlead. It may be a myth from the olden days, but 2+2 still
equals 4 - just like the old days. And its not a myth - it really does
work.

What frequency? What length? What loss did you measure? Was it raining?

freq= 2m band
length = approx 200 ft (up and accross the yard to the top of a TALL TREE)
loss ---- what loss did you measure w/ rg58 (which would have been the
other affordable line)
ie: I did not "measure" it - but my signal reports from others were 'much
improved' over the same antenna on the roof.

Raining? - rain, shine, - didn't matter - the run was in free air... I ran
about 10 ft coax out of the house - then switched to twinlead - then back
again near the antenna..
a wives tale - probably so - but I still feel better after eating chicken
soup if I have a cold.
but dogone it - it was fun - I did it - I'm proud of it - and I'll probably
do it again. - It was a good exercise in matching impedences --- I was a new
ham, and wanted to experiment...
I used it because it was light weight and low-loss (per the specs in the
belden catalog) - I don't have the catalog in front of me - but to get the
same low-loss-ness I could not afford the hard-line. - and the weight of
that run would have prevented the setup I had in mind.
Plus - I used it as a weather instrument:
if it was wet - rain : it was was swaying - windy, etc.

I understand the limitations of twin-lead and ladder-line, etc - and the
fact that rain and other objects may reduce its effectiveness, etc - but
even if the loss was half as good, it still beat the best coax I could
afford.
Oh - and I used a tree rather than a tower to hold the antenna. - Trees are
kind of old-fashion too, compared with the modern towers.

Of course twin-lead can "work" in a wide range of applications.

The myth is that it can beat a modern coax cable at VHF, on a long run
with practical installation difficulties, and in the rain.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek


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I am finally going to put up a VHF antenna for 2 meter and another antenna
for 70 cm.

What is type of coax should I use? Rg213? Or will RG213 be too lossy?

It depends on what you wan to do . As mentioned use the lowest loss you can
afford. The 5/8 inch hard-line is great but not many will want to pay the $
5 per foot and about $ 70 per connector and put up with the stuff not being
easy to bend.

Look at the LMR 400 or Belden makes some that is hard to find I think is
called 9914. It has almost the same low loss as the 9913 but uses a solid
dielectric instead of the hollow type of the 9913. If you are only using 30
or 40 feet and mostly the FM repeaters, the RG8x type is ok. As someone
mentioned the RG 6 type sold for cable TV is fine for a run of 50 feet or
so. The on;y problem is the connectors. IT is 70 ohm coax but for most
simple systems it will not mater.

I have used most all of the above but the hard-line at home and it all
depends on what I was doing. I only want a few local repeaters for a rig in
the house so a homemade dipole (vertical) is up about 25 feet on the tower.
It has about 40 feet of rg59 and then about 30 feet of rg58 going to it.
Not the best but it works fine for what I am doing. I also have a 2 meter
ssb rig in the shack that is fed with the 9913 and it seems to work ok for
it. Using a dual band antenna to a scanner that is programmed with 2 meter
and 440 repeaters and feeding it with about 100 feet of rg8x. The 2 meter
part works great but not so good on the 440 band.
The satellite antennas are feed with the 9913 and sofar I have been able to
keep the water out of the coax.

On Sun, 30 May 2004 10:44:15 -0400, Rob hath writ:

I am finally going to put up a VHF antenna for 2 meter and another antenna
for 70 cm.
What is type of coax should I use? Rg213? Or will RG213 be too lossy?
Recommendations please...

Cable TV Hardline. You can't beat the price. HI!HI!

http://jonz.net/W3DHJ/catvhardline.html

73
Jonesy
--
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| Gunnison, Colorado | @ | Jonesy | linux __
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