The AM Forum

 Found this at the DeAnza Swap Meet, I had never seen this stuff before until a few years ago, a ham I know uses it to feed an all band dipole through a Johnson Matchbox. The spacing is an inch, small gauge copper weld wire.

 I wonder how much power it might handle?? Legal Limit???

Nice find!  I bought a 100 foot roll of the stuff decades ago.  I successfully used that 450 ohm OWL as a teen for my dipole.  The transmitter was an Eldico TR-1, the feed line was fed with a link coupled tuner.  It should handle legal limit AM.  You will need a link coupled tuner to effectively use it.

GL, Al, W1VTP

I have some of that exact line and have used it at 1.5 kilowatts with no problems.  Right here in the shack there is also a jumper of it that goes from my tuner up to the feedthroughs to the big line outdoors.  Tuning on all bands I've never had a whimper from it.
I have visited the DeAnza swap a few times on business trips to Silicon Valley and have always found good stuff.  

Here's my stuff

In the early days of television, OWL had the least loss of any transmission line.  Probably used before they started making plastic 300ohm twin lead.  I still have over 3000ft of twin lead in stock.  Never use it, probably have to scrap it at some point.

Fred

I know of this kind being used at 3KW PEP in tests but it depends on the impedance and match, current nodes, etc. Good stuff.

Yes, it depends on how big the mismatch becomes on various bands (open wire swr) and the power level used.  There may be situations where there is 30-40 amps at the feed line current peaks. (or more)


Take an extreme case:   A 75M dipole used on 160 M at 1KW AM carrier level.  Those plastic spacers would be falling to the ground on fire yelling "Oh the humanity!! ".  ;D

But most situations will be fine. The best way to find out is to run a test on all the frequencies. Put a 50% modulated tone through for AM and after a few minutes do a touchy feely of the feed line along at least 1/2 wavelength of the run.  (Feeling the feedline only in the shack is inconclusive because it could be a voltage peak with little current there.) If it is less than lukewarm anywhere on the run for say, 300 watts, you should be fine. Test it on all the bands you will be using.

For perfectionist hams with high current peaks, losing a few dB in heat is unacceptable and will cause sleepless nights. The same dB level is lost whether running 1 watt or 1000 watts.  The only solution then is not to be lazy and construct your own open wire line using #12 wire or larger and using Plexi, Teflon, Lexan or whatever 4-6" spacers.

The link coupled antenna matcher should also be of robust quality components.

T

That's what I feed my 200' center feed dipole with series HB tuner(75/80 meters) or parallel feed on the Johnson Matchbox for the higher bands.

Bought two 500' reels of it looong, long time ago...

I've put full legal CW power on it with no problems...

Hey Fred, put your surplus up for sale, EPAY is your friend...

EDITED 8/13/15...

As Tom mentions in the first paragraph's of his response, I have had the spacers dissipate for a couple feet, once or twice, misterislly into the night...

Was not a problem,  stuck a couple 3" ceramics in and kept on going.   That line is still in the air...

The ladder line looks really nice. What type of insulators are used? Will they be any problem running QRO?

Fred

Fred, read the thread then make 51watt Fred an offer for a couple  hundred feet of his surplus... That is if he still has any of the OW line...

W1VTP

A little off topic, but when was the last time that model 15 was turned on, or do you even have it any more.

Mike

It's fully operational.  I use either a homebrewed TU, very good design, or a Dovetron MPC-1000R.  I used that unit a lot back in the day.  We can talk about it via email if you wish

Al

Speaking of which,

This company still makes ladder Line(saw this in ER Mag):

http://trueladderline.com/


Phil - AC0OB