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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Bob Miller wrote in message . ..
On Mon, 31 May 2004 17:52:59 GMT, Gary S. Idontwantspam@net wrote:

On Mon, 31 May 2004 12:37:31 -0500, Cecil Moore
wrote:

Gary V. Deutschmann, Sr. wrote:
And, do you want to trust factory installed cheap connectors?

Installed by minimum wage workers?

Who are judged by speed, not quality?


Well, the average ham with a mighty 40-watt soldering iron and rusty
pliers isn't going to do much better. At least the minimum wage guys
are probably making cables with good tools -- 120-watt or better
Weller irons with 1/2" tips, etcetera...

Speaking of tips . . here's one. I've never been happy with any of the
Weller irons, not even the clunky big 300W versions when it comes to
"doing" PL-259s. Turns out that Sears has a very light and compact
transformerless pistol type "instant heat" 400/150 watt iron which I
bought for $59.95 about a year and a half ago. Does a great job on
connectors and heavy antenna wire.

Bob
k5qwg

w3rv

Brian Kelly wrote:
Well, the average ham with a mighty 40-watt soldering iron and rusty
pliers isn't going to do much better. At least the minimum wage guys
are probably making cables with good tools -- 120-watt or better
Weller irons with 1/2" tips, etcetera...

Speaking of tips . . here's one. I've never been happy with any of the
Weller irons, not even the clunky big 300W versions when it comes to
"doing" PL-259s. Turns out that Sears has a very light and compact
transformerless pistol type "instant heat" 400/150 watt iron which I
bought for $59.95 about a year and a half ago. Does a great job on
connectors and heavy antenna wire.

I've never been happy with monster irons either, but have had very good
results using a hot-air gun as 'pre-heat' for my regular 45W Weller.

It's very easy to judge how long to pre-heat the whole connector body.
Then the regular small iron has plenty of power to make a good, clean
joint in the solder holes. The same technique is also good for fine
soldering work on large lumps of metal.

The bonus is that a hot-air gun is much cheaper than a large iron, and
you can also use it for other things too, like heat-shrink tubing. (Did
somebody mention removing old paint? What's this "paint" stuff? :-)

It isn't a technique to use at the top of a tower... but there isn't
*any* good way to do heavy soldering under those conditions. For that
kind of application, seek out the pressure-sleeve connectors that only
require the center pin to be soldered.


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

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 ...
Brian Kelly wrote:
Well, the average ham with a mighty 40-watt soldering iron and rusty
pliers isn't going to do much better. At least the minimum wage guys
are probably making cables with good tools -- 120-watt or better
Weller irons with 1/2" tips, etcetera...

Speaking of tips . . here's one. I've never been happy with any of the
Weller irons, not even the clunky big 300W versions when it comes to
"doing" PL-259s. Turns out that Sears has a very light and compact
transformerless pistol type "instant heat" 400/150 watt iron which I
bought for $59.95 about a year and a half ago. Does a great job on
connectors and heavy antenna wire.

I've never been happy with monster irons either, but have had very good
results using a hot-air gun as 'pre-heat' for my regular 45W Weller.

It's very easy to judge how long to pre-heat the whole connector body.
Then the regular small iron has plenty of power to make a good, clean
joint in the solder holes. The same technique is also good for fine
soldering work on large lumps of metal.

That's clever, I have a heat gun (somewhere), I'll try it. Sounds like
the method might reduce the total number of BTUs/calories absorbed by
the dielectric which has always been a concern here. Barbequed coax is
very annoying.


The bonus is that a hot-air gun is much cheaper than a large iron, and
you can also use it for other things too, like heat-shrink tubing. (Did
somebody mention removing old paint? What's this "paint" stuff? :-)

It isn't a technique to use at the top of a tower... but there isn't
*any* good way to do heavy soldering under those conditions.

.. . . propane torch . .

For that
kind of application, seek out the pressure-sleeve connectors that only
require the center pin to be soldered.

w3rv

Brian Kelly wrote:
I've never been happy with monster irons either, but have had very good
results using a hot-air gun as 'pre-heat' for my regular 45W Weller.

It's very easy to judge how long to pre-heat the whole connector body.
Then the regular small iron has plenty of power to make a good, clean
joint in the solder holes. The same technique is also good for fine
soldering work on large lumps of metal.

That's clever, I have a heat gun (somewhere), I'll try it. Sounds like
the method might reduce the total number of BTUs/calories absorbed by
the dielectric which has always been a concern here. Barbequed coax is
very annoying.

If you prefer your PVC under-cooked, wrap some aluminum foil around
it... and don't point the heat gun that way :-)


The bonus is that a hot-air gun is much cheaper than a large iron, and
you can also use it for other things too, like heat-shrink tubing. (Did
somebody mention removing old paint? What's this "paint" stuff? :-)

It isn't a technique to use at the top of a tower... but there isn't
*any* good way to do heavy soldering under those conditions.

. . . propane torch . .

Yeah, right...


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

It is perhaps worth noting that all the cute comments about cheap
materials and labor would apply equally well to nearly all the products
we buy these days. Who here makes all his own clothes and shoes,
for example?

As to cables, some sources (e.g., Cable Experts) seem to pride
themselves on good quality. And it would be a sad state of affairs if
they (and other professional cable makers), couldn't install connectors
much faster AND better than the typical ham with his motley hand tools.

Some exotic cable types are not even spec'ed for user-installed
connectors, by the way--even if said user is a competent electronics
house. Such cable types REQUIRE factory-installed connectors.
(This is NOT stuff needed by the average ham, fortunately.)

Notwithstanding all this, there are undeniably some junky, Chinese
ready-made cables out there. I bought a few from HRO, and about 20%
turned out to be bad. So now I will buy only the relatively upmarket
ready-mades (like Cable Experts). I notice that our local HRO seems
to be phasing out the no-name ready-mades; so I suspect I wasn't the
only one to have problems with them.

73, Ed

"Gary S." Idontwantspam@net wrote in message
...
On Mon, 31 May 2004 12:37:31 -0500, Cecil Moore
wrote:

Gary V. Deutschmann, Sr. wrote:
And, do you want to trust factory installed cheap connectors?

Installed by minimum wage workers?

Who are judged by speed, not quality?

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

(nt)

"Old Ed" wrote in message
ink.net...
.............................................
Notwithstanding all this, there are undeniably some junky, Chinese
ready-made cables out there. I bought a few from HRO, and about 20%
turned out to be bad. So now I will buy only the relatively upmarket
ready-mades (like Cable Experts). I notice that our local HRO seems
to be phasing out the no-name ready-mades; so I suspect I wasn't the
only one to have problems with them.

73, Ed

It's also worthwhile seeing what the cable looks like. A couple of years ago
I bought 100 feet of generic (Carol?) RG8 foam. Looked OK. Next time I
bought a 25 foot piece of the same brand with connectors. Well, when the
connector came off, I saw it was not the same cable; next to no shield.

Tam/WB2TT

I have some andrews 1 5/8 coax, a 75 and 110 piece. No ends just the
coax.
Any takers. I am in Daytona FL.
Say $100 and $150 for them.


On Wed, 2 Jun 2004 20:23:35 -0400, "Tam/WB2TT"
wrote:


"Old Ed" wrote in message
link.net...
.............................................
Notwithstanding all this, there are undeniably some junky, Chinese
ready-made cables out there. I bought a few from HRO, and about 20%
turned out to be bad. So now I will buy only the relatively upmarket
ready-mades (like Cable Experts). I notice that our local HRO seems
to be phasing out the no-name ready-mades; so I suspect I wasn't the
only one to have problems with them.

73, Ed

It's also worthwhile seeing what the cable looks like. A couple of years ago
I bought 100 feet of generic (Carol?) RG8 foam. Looked OK. Next time I
bought a 25 foot piece of the same brand with connectors. Well, when the
connector came off, I saw it was not the same cable; next to no shield.

Tam/WB2TT