Go Back   WorldwideDX Amateur Radio Forums > Amateur Radio Related > Amateur Radio Antennas


Amateur Callsign Lookup
Enter Callsign:

600 Ohm Ladder Line vs Coax

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 07-18-2010, 11:44 AM
Robb's Avatar
Yup
iTrader: (3)
 
Join Date: Dec 2008
Location: Silicon Valley CA, Storm Lake IA
Posts: 8,088
Robb is on a distinguished road
Arrow 600 Ohm Ladder Line vs Coax


Since I'm about to put up a dipole; should I use 600 ohm ladder line? Many Hams consider the 600 ohm line better than the 450 and 300 ohm stuff. Why is that so?

Why is it preferable to coax? What are the advantages? What are the disadvantages? Should I use a specific length for a given band of antenna - say a 10-80m fan dipole?

I believe a Balun would be needed. Because it is a 600 ohm feed; what balun ratio would be necessary? Would I need ferrites on the coax when it mates to the 600 ohm line?

__________________
BASE: Kenwood TS-2000, GAP Titan DX, Diamond X50A, Sirio SY27-4, and IMAX 2000.
MOBILE: Galaxy DX99V w/RF Limited CR-577 mic, Sirio Z-180. Yaesu FT-8800R & Diamond NR-770.


Reply With Quote
  #2  
Old 07-18-2010, 12:23 PM
EDUK8TR's Avatar
W9WDX Amateur Radio Club Member
iTrader: (3)
 
Join Date: Apr 2005
Location: West Central Highlands, VA
Posts: 934
EDUK8TR is on a distinguished road
Default

Greetings Rob!

I use 600 Ohm ladder line. It is used on a 40m horizontal delta loop. The ladder line runs down to a DX Engineering 4:1 current balun that is mounted on the outside of the basement wall with about 12 ft. of RG8 to a tuner to keep the rig happy with a 50 Ohm load. Advantages-low loss(as long as you keep the coax run less than 15-20ft, any thing above that then losses in the coax go up), Multi-band use with a tuner. There is a discussion herehttp://www.eham.net/ehamforum/smf/index.php/topic,69646.0.html
regarding ladder line length.

Hope this helps!

Wayne C
__________________
"To be is to do"-Socrates;

"To do is to be"-Sartre;

"Do Be Do Be Do"-Sinatra;

WV4L,CDX-787,AK2787
Mobile/Base
Icom70000/Kenwood TS-2000 w/LDG AT-1000ProII
Stock mic or W2ENY headset on VOX/D104 w/Heil HC-5 or W2ENY headset on VOX
Tarheel 200A-HP w/N2VZ Turbo Tuner,Larson NMO 2/70B/TX-472 tower w/ 80M Horizontal Delta Loop, 20-6M K4KIO Hex beam, Gulf Alpha Dual Band Cross Polarity 7X7El. 2M:10 El.v70 CM beam, Arrow 146-440GP
Ameritron AL80A

Reply With Quote
  #3  
Old 07-18-2010, 01:16 PM
Senior Member
iTrader: (0)
 
Join Date: Jun 2009
Location: Hartford, MI
Posts: 502
office888 is on a distinguished road
Default

Here's the advantage.

Db loss / 100ft:
1 mhz : 0.019 dB
30 mhz : 0.107 dB
100 mhz : 0.2 dB
500 mhz : 0.474

TMS LMR400
1 : 0.12 dB
30 : 0.667 dB
100 : 1.232 dB
500 : 2.841 dB

200 ft of 600 ohm Ladder Line, 16GA Stranded, 100% copper = $136 shipped
200 ft of TMS LMR-400 = $219 shipped

I'll be using ladder line for my 10-80 or 10-160 dipole (we'll see if I can "borrow" my neighbor's tree!)

-Richard-
__________________
KD8NPB
Catch me on the K8BRC 147.360 repeater!

Reply With Quote
  #4  
Old 07-18-2010, 02:39 PM
Crotchety Old Bastard
iTrader: (0)
 
Join Date: Apr 2005
Location: Oklahoma
Posts: 6,915
W5LZ is on a distinguished road
Default

Having only used 450 ohm ladder line, I can' say from experience if there's any advantages to using 600 ohms ladder line. I can say that if I have a choice in the matter, I'd much rather use ladder line than coax, it's just not as 'picky' about getting 'upset' if the SWR isn't very good. I've messed up coax before, harmed it, but have never destroyed any ladder line with RF yet (did run over some with the @#$ lawn mower, but that doesn't count).
What length? That depends. I use a very good tuner and don't worry much about the length. If I find a band that I/you can't get to tune very well, I/you can always adjust the length a couple of feet and 'cure' that. It's also possible to just use a balun and a particular length for any single band use, and end up with a close to 50 ohm input impedance. If you plan to use that antenna on multiple bands, get a good tuner, makes things much easier. (No, tuners don't mean any more losses than any other means of impedance matching, less in most cases.)
Ladder line means learning different ways of handling things than with coax. Can't run it just anywhere, or coil it up, or lay it on the ground. It's certainly not impossible to use, but it is different.
I like the stuff. Don't have to worry about SWR like with coax, it's awful hard to damage with RF, and can make a difference in performance in some cases. (And it's cheap!)
- 'Doc

Reply With Quote
  #5  
Old 07-18-2010, 05:01 PM
Robb's Avatar
Yup
iTrader: (3)
 
Join Date: Dec 2008
Location: Silicon Valley CA, Storm Lake IA
Posts: 8,088
Robb is on a distinguished road
Default

Is the only advantage less 'line loss'?
Does it have anything else to offer to bandwidth, sensitivity, etc?
__________________
BASE: Kenwood TS-2000, GAP Titan DX, Diamond X50A, Sirio SY27-4, and IMAX 2000.
MOBILE: Galaxy DX99V w/RF Limited CR-577 mic, Sirio Z-180. Yaesu FT-8800R & Diamond NR-770.

Reply With Quote
  #6  
Old 07-18-2010, 06:16 PM
Beetle's Avatar
Senior Member
iTrader: (0)
 
Join Date: Dec 2005
Location: Western Washington
Posts: 2,470
Beetle is on a distinguished road
Default

Quote:
Originally Posted by Robb View Post
Is the only advantage less 'line loss'? Does it have anything else to offer to bandwidth, sensitivity, etc?
Bandwidth isn't really a factor; you WILL have to use a matching network, and I'd recommend a manual one, especially if you're going to be running any amount of power - say 500 watts or more.

As for a balun...you won't need one if you're running the parallel line all the way to the matching network (assuming it's really a balanced network, as it should be). If you're running 50 ohm coax from the shack to the outside and then going with a balun and parallel line the rest of the way, I'd start with a 1:1 current balun. At some points, the feedpoint impedance may be well below 50 ohms, and a 4:1 will reduce it even further, such as a 20 ohm impedance transformed to 20/4, or just 5 ohms. Your tuner will be carrying more current than it can handle, possibly with a predictable outcome.

Not sure what you mean by "sensitivity". That's a receiver function.

And as far as line loss, that info that Richard posted only indicates loss for x feet of coax at a 1:1 SWR, or zero reflected power. With an 80 meter dipole being fed RF at 7 MHz (as an example), the SWR will easily be 10:1 or even worse. This is where the parallel line shines: even at 10:1 (or 30:1), your RF will be radiated and not wasted heating up a piece of coax.
__________________
If you're like everybody else,
you're about average.
73 de K7KBN
CWO4 USNR RET.

Reply With Quote
  #7  
Old 07-18-2010, 07:42 PM
Robb's Avatar
Yup
iTrader: (3)
 
Join Date: Dec 2008
Location: Silicon Valley CA, Storm Lake IA
Posts: 8,088
Robb is on a distinguished road
Default

Quote:
Originally Posted by Beetle View Post
Bandwidth isn't really a factor; you WILL have to use a matching network, and I'd recommend a manual one, especially if you're going to be running any amount of power - say 500 watts or more.
Not going to run power at this point; as I want to get this all one step at a time. I have an MFJ-993B Intellituner rated @300W. Or do I have to start at ground zero and get another/different one?

Quote:
Originally Posted by Beetle View Post
As for a balun...you won't need one if you're running the parallel line all the way to the matching network (assuming it's really a balanced network, as it should be). If you're running 50 ohm coax from the shack to the outside and then going with a balun and parallel line the rest of the way, I'd start with a 1:1 current balun. At some points, the feedpoint impedance may be well below 50 ohms, and a 4:1 will reduce it even further, such as a 20 ohm impedance transformed to 20/4, or just 5 ohms. Your tuner will be carrying more current than it can handle, possibly with a predictable outcome.
As in the 'ugly balun'; just a choke to keep RF out of the shack? I would still need to have some coax into the shack, and keep the RF out - right? Or lotsa ferrite on the coax just after it hooks to the ladder line? How would this be best accomplished? I figure that I will have a need of about 90 ft from the dipole itself into my shack/tuner.

Quote:
Originally Posted by Beetle View Post
Not sure what you mean by "sensitivity". That's a receiver function.
AS in the db losses affecting what the receiver gets. I would rather get more signal into my receiver...even if its just a couple of db's...

Quote:
Originally Posted by Beetle View Post
And as far as line loss, that info that Richard posted only indicates loss for x feet of coax at a 1:1 SWR, or zero reflected power. With an 80 meter dipole being fed RF at 7 MHz (as an example), the SWR will easily be 10:1 or even worse. This is where the parallel line shines: even at 10:1 (or 30:1), your RF will be radiated and not wasted heating up a piece of coax.
In particular, it is a Alpha Delta DX-CC that I am looking in to. Mole recommended it to me, as I am planning to use it with the Navy MARS program if I get some more study in. Reading all of the time; some of this isn't intuitive and needs more detail.
http://www.alphadeltacom.com/dxcc_ii.htm
http://www.wb0w.com/alphadelta/ad_antennas.htm
__________________
BASE: Kenwood TS-2000, GAP Titan DX, Diamond X50A, Sirio SY27-4, and IMAX 2000.
MOBILE: Galaxy DX99V w/RF Limited CR-577 mic, Sirio Z-180. Yaesu FT-8800R & Diamond NR-770.

Reply With Quote
  #8  
Old 07-18-2010, 10:37 PM
Beetle's Avatar
Senior Member
iTrader: (0)
 
Join Date: Dec 2005
Location: Western Washington
Posts: 2,470
Beetle is on a distinguished road
Default

Quote:
Originally Posted by Robb View Post
Not going to run power at this point; as I want to get this all one step at a time. I have an MFJ-993B Intellituner rated @300W. Or do I have to start at ground zero and get another/different one?

You can try with the Intellituner; since each installation has its own characteristics, it's impossible to say whether it will have enough range or stamina to match the widely varying impedances you're going to see.

As in the 'ugly balun'; just a choke to keep RF out of the shack? I would still need to have some coax into the shack, and keep the RF out - right? Or lotsa ferrite on the coax just after it hooks to the ladder line? How would this be best accomplished? I figure that I will have a need of about 90 ft from the dipole itself into my shack/tuner.

No - an actual current balun. You shouldn't need a choke if the antenna is balanced.

AS in the db losses affecting what the receiver gets. I would rather get more signal into my receiver...even if its just a couple of db's...

Feedline characteristics are bidirectional. What's good for transmitting is good for receiving.

In particular, it is a Alpha Delta DX-CC that I am looking in to. Mole recommended it to me, as I am planning to use it with the Navy MARS program if I get some more study in. Reading all of the time; some of this isn't intuitive and needs more detail.
ALPHA DELTA DX-CC 82 FT
ad antennas
Okay, NOW you tell me it's a commercial multiband antenna! I thought when you said you were putting up a "dipole" it was just that: a plain, homebrew dipole fed with 600 ohm line. I believe the A-D line are multiband, like fan dipoles. They're heavy and they're optimized for the amateur bands. You might find MARS frequencies difficult to tune, if following the manufacturer's instructions.

Why not build a doublet, as long as you can make it, center fed with that 600 ohm line? It'll be a heckuva lot cheaper, lighter and less visible (also less wind load). I'd sure do that, given the choice.
__________________
If you're like everybody else,
you're about average.
73 de K7KBN
CWO4 USNR RET.

Reply With Quote
Reply

Bookmarks

Tags
antenna install, dipoles, ladder line
Worldwide Radio Forum



Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
coax length wewjr71 Installation & Station Setup 53 02-19-2009 01:21 PM
Adjusting SWR with amp T-bone CB Antennas 59 03-27-2008 06:48 PM
coax or ladder line CDX1220 General Ham Radio Discussion 10 10-04-2007 05:13 PM
length of coax country boy jr CB Antennas 28 04-08-2006 08:03 AM


All times are GMT -7. The time now is 05:44 AM.


Powered by vBulletin®
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.0
Worldwide Radio Forum