The AM Forum
July 17, 2024, 02:42:16 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: Swap Meet Find, TV Ladder Line  (Read 9848 times)
0 Members and 1 Guest are viewing this topic.
W6TOM
Contributing
Member
*
Offline Offline

Posts: 460


« on: August 08, 2015, 08:07:46 PM »

 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???


* Box.JPG (335.38 KB, 1024x768 - viewed 707 times.)

* Ladder Line.JPG (336.73 KB, 1024x768 - viewed 743 times.)
Logged
w1vtp
Member

Offline Offline

Posts: 2632



« Reply #1 on: August 08, 2015, 09:17:38 PM »

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
Logged
W1ITT
Member

Offline Offline

Posts: 577


« Reply #2 on: August 08, 2015, 09:20:09 PM »

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.  
Logged
w1vtp
Member

Offline Offline

Posts: 2632



« Reply #3 on: August 08, 2015, 09:35:49 PM »

Here's my stuff


* 450 OHM OWL 1.jpg (369.2 KB, 3140x3918 - viewed 809 times.)

* 450 OHM OWL 2.jpg (446.09 KB, 3639x3054 - viewed 782 times.)
Logged
KA2DZT
Member

Offline Offline

Posts: 2190


« Reply #4 on: August 08, 2015, 10:31:44 PM »

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
Logged
Opcom
Patrick J. / KD5OEI
Contributing
Member
*
Offline Offline

Posts: 8281



WWW
« Reply #5 on: August 08, 2015, 11:04:00 PM »

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.
Logged

Radio Candelstein
K1JJ
Contributing
Member
*
Offline Offline

Posts: 8886


"Let's go kayaking, Tommy!" - Yaz


« Reply #6 on: August 09, 2015, 12:12:51 PM »

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!! ".  Grin

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

Logged

Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed.  Easily done in DSP.

Wise Words : "I'm as old as I've ever been... and I'm as young as I'll ever be."

There's nothing like an old dog.
Ralph W3GL
Contributing
Member
*
Offline Offline

Posts: 748



« Reply #7 on: August 09, 2015, 04:18:12 PM »

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...

Logged

73,  Ralph  W3GL 

"Just because the microphone in front of you amplifies your voice around the world is no reason to think we have any more wisdom than we had when our voices could reach from one end of the bar to the other"     Ed Morrow
flintstone mop
Contributing
Member
*
Offline Offline

Posts: 5047


« Reply #8 on: August 12, 2015, 06:09:09 PM »

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

Fred
Logged

Fred KC4MOP
Ralph W3GL
Contributing
Member
*
Offline Offline

Posts: 748



« Reply #9 on: August 13, 2015, 03:06:36 PM »

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...
Logged

73,  Ralph  W3GL 

"Just because the microphone in front of you amplifies your voice around the world is no reason to think we have any more wisdom than we had when our voices could reach from one end of the bar to the other"     Ed Morrow
MikeKE0ZUinkcmo
Member

Offline Offline

Posts: 443



« Reply #10 on: August 14, 2015, 07:27:57 AM »

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
Logged

Mike KE0ZU

Bold Text and PICS are usually links

https://mikeharrison.smugmug.com/
w1vtp
Member

Offline Offline

Posts: 2632



« Reply #11 on: August 15, 2015, 05:14:00 PM »

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
Logged
DMOD
AC0OB - A Place where Thermionic Emitters Rule!
Contributing
Member
*
Offline Offline

Posts: 1777


« Reply #12 on: August 15, 2015, 06:03:34 PM »

Speaking of which,

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

http://trueladderline.com/


Phil - AC0OB
Logged

Charlie Eppes: Dad would be so happy if we married a doctor.
Don Eppes: Yeah, well, Dad would be happy if I married someone with a pulse.NUMB3RS   Smiley
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.055 seconds with 19 queries.