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


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