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300 ohm ladder line on 11 meters ?

B

BOOTY MONSTER

Guest
just for discussion .................
on a 50 ft to 200 ft run what are the pros and cons of using 300 ohm ladder line rather than 50 ohm coax on 11 meters ? i know a balun is necessary , but how would this be done ? have you tried it ? whats your thoughts or questions about it ?
 

BammBamm

Instigators ...173 on the southside.
May 24, 2010
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I would think the coax would be easier. How much of a lose difference would there be between LMR400 and ladder line at 100 foot?
 
B

BOOTY MONSTER

Guest
thus the reason for my interest . but there's always give and take . from what i can tell its just a bit more effort and a little extra thinking . is ladder line more likely to bleed than coax ? i've thought for a while that a higher % of shield on coax the better it might be at keeping the signal from leaking out and effecting nearby electronics , but ladder line has no shield and i don't recall reading any comments about it bleeding more than coax . also , is ladder line more or less likely to have common mode current issues ? and , since ladder line only has 2 surfaces for the signals to travel on , how or dose that effect any thing compared to coax with 3 surfaces ?
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
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Ladder line for a single band like CB is ridiculous at lengths of 50 to 200 feet. The losses will be very low but the additional losses of any baluns etc may negate that advantage of using ladder line in the first place.A fraction of a dB will not be noticed. Ladderline needs to be run straight and free of metallic objects and grounded objects. If you had to run several hundred feet or wanted to operate on several bands where the SWR would be extremely high at times then ladder line is the way to go.

BTW ladder line does not radiate because the currents carried in each leg are equal in amplitude and of opposing phases and thus cancel out completely.
 

AudioShockwav

Extraterrestrial
Staff member
Apr 6, 2005
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A Quote from Steve Ford, WB8IMY, from The Lure of the Ladder Line





Since I insisted on sticking with a single-dipole design, Dean suggested that I replace my coaxial cable with ladder line. Unlike coax, where one conductor completely surrounds another, ladder line places both conductors in parallel. Insulating material is used to maintain a consistent separation. As a result, the fields radiated by the conductors cancel each other and the line is balanced.


Full text can be found here
The Lure of the Ladder Line

Good reading Here.

All About Ham Radio ladder-line

Ladder line is most often used for multi band antennas.

73
Jeff
 
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B

BOOTY MONSTER

Guest
thanks guys .
hey CK . since baluns add loss , do air core coax chokes also add loss . is the loss of either likely to be detectable buy human ears on a radio ?
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
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thanks guys .
hey CK . since baluns add loss , do air core coax chokes also add loss .

Yes. Anything no matter how insignificant will add losses to some degree no matter how minimal.


is the loss of either likely to be detectable buy human ears on a radio ?


Not unless the builder really Eff'ed up big time and did something really stupid. An added losss of 1 dB is high when talking about what a balun should normally introduce into a system and that is going to be undetectable on the receive end.
 
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Needle Bender

...he thinks it's funny that I stepped in it
May 15, 2010
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What about just shorting the ends of the 300 ohm and tapping it back a bit at the 50 ohm point for the 50 ohm coax to attach, like a stub match?
 
Last edited:

RatsoW8

Supporting Member, W9WDX ARC Member - WD8T
Nov 3, 2009
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Ladder line for a single band like CB is ridiculous at lengths of 50 to 200 feet. The losses will be very low but the additional losses of any baluns etc may negate that advantage of using ladder line in the first place.A fraction of a dB will not be noticed. Ladderline needs to be run straight and free of metallic objects and grounded objects. If you had to run several hundred feet or wanted to operate on several bands where the SWR would be extremely high at times then ladder line is the way to go.

BTW ladder line does not radiate because the currents carried in each leg are equal in amplitude and of opposing phases and thus cancel out completely.

This pretty much says it all. Ladder was used more for multi-band antennas and not single band resonant ones in the day. Why bother with the construction headaches and additional cost?

ladder line was also the low cost alternative for hams before coax was the less expensive and easily obtained. Back then hams made their own ladder line. We don't have to do that anymore.

If you just looking to build the antenna for giggles then do it but it's not going to net any benefits in the end over using an unbalanced feed-line.
 

Needle Bender

...he thinks it's funny that I stepped in it
May 15, 2010
1,403
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This pretty much says it all. Ladder was used more for multi-band antennas and not single band resonant ones in the day. Why bother with the construction headaches and additional cost?

ladder line was also the low cost alternative for hams before coax was the less expensive and easily obtained. Back then hams made their own ladder line. We don't have to do that anymore.

If you just looking to build the antenna for giggles then do it but it's not going to net any benefits in the end over using an unbalanced feed-line.

How about the cost factor?
200' of low loss LMR400 sure costs a lot more than 200' of even 450 ohm twin lead, let alone 300 ohm, and there should still be considerably more than only a negligible difference in loss, especially if 450 ohm were used with simple stub matches or a set of paired 75 ohm electrical 1/4 wave matching transformers.
1.3db at 200' for LMR400 compared to .3db for 450 ohm. That's about 20 more watts per hundred not lost, or about a 20% overall gain on both RX and TX.
I think >100' length is a better demarcation point between the two choices.

The calculator I used, Coax Loss Calculator
 

wavrider

W9WDX Amateur Radio Club Member
Jun 2, 2009
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If you have some ladderline laying around it will be fun and a learning experience to play with building antennas with it as a feed line.

300 ohm TV ladderline is good for up to 100 watts.

Friend of mine uses twinlead RG6 for the old C band satellite dishes, works great using the center conductor as the feed and shorting the shields together at the antenna feed point, the shield is connected to the ground in the shack at the antenna coupler. He swears by it and only runs this on his ham antennas.

The loss of the transmission line at HF frequencies is very small, so if you got the ladderline try it, cheaper than LMR400 and it will work.
 

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