Quest on homebrew ladder line

[WA2SQQ]

I'm tired of replacing the cheap commercial ladder line on my G5RV. Decided it's time to make my own. I've been reading that the impedance is not that critical. Thinking of using #14 wire, with 2" spacing.

I also need to figure out how to get the ladder line into the shack - no windows!
Someone told me I could use two short lengths of coax, with their shields tied together?

Any suggestions would be very much appreciated.

Bob, WA2SQQ

[KD6VXI]

I'm tired of replacing the cheap commercial ladder line on my G5RV. Decided it's time to make my own. I've been reading that the impedance is not that critical. Thinking of using #14 wire, with 2" spacing.

I also need to figure out how to get the ladder line into the shack - no windows!
Someone told me I could use two short lengths of coax, with their shields tied together?

Any suggestions would be very much appreciated.

Bob, WA2SQQ

I used #10 at 6 inches, but that's what I had a few hundred feet of.  It's also the full sized 160 dipole.

To get the ladder line in the house the easiest way I found was to drill a couple 1/8 to 1/4 inch holes from inside the shack, near where your tuna will be, completely through the walls and siding, making a clear cut so you can see daylight.

Then, stuff some identically sized (as the holes you drilled) brass allthread through.  I used a washer on the outside that had a rubber grommet built in, then a couple more brass nuts and washers to connect the ladder line to.

On the inside, same thing.  Used some LARGE flat fender washers on the inside, though...   Figured the larger washers would spread the load across the sheetrock better as well as don't need weatherproofing:  I get no leaks of air even with 100+ MPH wind gusts.

If you ever have to move, easy as pie.  A couple dabs of toothpaste or spackle on the inside, and a couple weatherproof screws outside.  No leaks, nobody notices.  I also liked the idea of the connection to the LL being under the eave of the house since my weather here is not friendly.  Used a piece of 1x1 to extend from the eaves out into the yard, and mounted one of my spreaders to that.  That covers the spacing from the house issue, and gives me a great flex free run to the allthread.

Hope this helps, your mileage may vary.

--Shane
KD6VXI

[W4NEQ]

Your #14 with two inch spacing will be fine.  I would however advise against coax through the wall though, unless you've removed the braid entirely.  Better just to insulate it well through small pvc tubes or similar - you don't want any possibility of it meeting up with semiconducting material which might be flammable.

My 2 inch #10 shown below.

Chris

[wa3dsp]

I used #12 house wire (#14 would be fine also) and I was lucky enough to have a box of original old ceramic spacers. The spacing was about 2 inches. Somewhere there is a chart (maybe in one of the antenna books) of impedance verses wire size and spacing. It does not vary that much - typically 400-600 ohms in 2-6" spacing unless you are using very large or small wire sizes.

Not sure how much power you are running and how far you have to go inside but in my case I used a Heath air coil balun right outside the house in a water proof box and about 10 feet of RG214 to the inside and a tuner. As an added measure of isolation I also added an MFJ coax balun in series with the RG214 inside the box. It is just coax fed through a series of ferrites. This works well here. The antenna is a non-resonant rectangular loop - about 320 feet of wire. The balun is wire 4:1. This would be good up to about 200 watts. The limiting factor is the Heath air balun.

I realize you are just trying to recreate the open wire section of a G5RV. That is actually part of the antenna and maybe a little more critical that just transmission line. You should match the length but if you want to dump that antenna all together a full length 80 (or 160) meter dipole or inverted V fed with open wire line makes a great multi-band antenna. You could use the balun method to bring the open wire line into the house as I did above. Just keep the coax section short. Some bring open wire line into the house but you need to be particularly careful of lightning and objects coming in contact with the line. There are ways to lightning protect open wire line but the best method is complete disconnection. Undoubtedly you will forget to do it at the worst possible time so a relay or solenoid arrangement to disconnect is a good idea.

[aa5wg]

Hi Bob,

I agree!  Home brew ladder line is the way to go.  With your dimensions you should have approximately a 501 ohms ladder line with #14 wire spaced 2 inches.

Here is a neat calculator you can use to calculate your home brew ladder line:  http://www.smrcc.org.uk/tools/OpenWire.htm

Remember to use "RADIUS" with this calculator and not diameter.  I kept using diameter and calculations were wrong.  

I have used ceramic feed thru insulator with two different sizes of grey PVC pipe glued on the inside of the two half insulators.  The two PVC pipes slide into each other.  This method works for different size walls.  I feed a brass threaded rod thru both insulators and pipe and use brass washers and nuts.  The ladder line connects to the brass threaded rod.

I am going to try another method to feed my next ladder line antenna.  I am drilling two holes thru the wall to the outside world.  One hole for each side of the ladder line.  I then slip a white PVC pipe thru both holes.  I place two end caps on both pipes.  I drill a small hole in the center of the end caps and place brass threaded rod thru the pipe.  I then add washers and nuts.

Remember to match the size of the brass rod to the size of the wire.  Smooth brass rod with just the ends having threads is better.  

Good luck and enjoy your very nice home brew ladder line.

Chuck

[WA2SQQ]

Appreciate all the responses, and I fully agree that a full sized dipole fed with open wire would be much better. My situation is such that the tower is in front of the garage, about 50 ft from the house. I have two underground runs of 7/8" running to the base of the tower. The shack is in the basement, and getting any open wire directly to the tuner is not easy. The property dimensions just allow me to get the G5RV squeezed in, as an inverted V.

The G5RV gets out great on 40, but sucks on 75. I'm thinking about trying a dedicated 75m dipole with some loading coils to  shrink it down to ~ 102 ft. Step one will likely be replacing the ladder line with something more substantial. I was also thinking about using a remote tuner at the base of the tower. Not sure how that would play out.

[aa5wg]

Bob,

In a past antenna project I could not get the ladder line in the shack without tons of interaction from other wires in house.  To help with this challenge I used two coax cables tied together "acting" as  ladder line.
I then ran the two or twin coax feeders from my link antenna coupler all the way to the antenna and it worked great.  Many guys tune up short center fed 80 meter antennas with the link coupler.

Chuck

[W2PFY]

The subject of "open wire line" comes up so often that it almost deserves it's own section so we could over the years go back and get all this useful information in one place.

[aa5wg]

I agree.  Ladder line, open wire feeders could use its own section.  And, link antenna couplers could use its own section.

Chuck

[Pete, WA2CWA]

Why not a section for tubes, or coax, or 101 variations of a dipole antenna, etc. If you use the Search function, you really don't need a lot of separate sections.

[WA2SQQ]

So I need to ask this question. How about, if I install a remote tuner at the base of the tower that could directly interface to the ladder line. The unknown I'd like to better understand is how well it would work if there was about 75 ft of coax between the tuner and the transmitter. The 75ft would be 7/8" hard line.

Most of the remote tuners (like LDG / MFJ) only have coax connections, so I assume I'd have to use a 4:1 balun?

[W4NEQ]

Tuner feeds ladder line - then coax to shack.  That would be the ideal arrangement.  It is always best to operate coax close to its design impedance, and avoid tuning it.  Gotta waterproof the tuner...

Chris

[Steve - K4HX]

If you are looking at a remote tuner, consider the ZS6BKW antenna. You would only need a tuner on 75 meters.

[K5UJ]

So I need to ask this question. How about, if I install a remote tuner at the base of the tower that could directly interface to the ladder line. The unknown I'd like to better understand is how well it would work if there was about 75 ft of coax between the tuner and the transmitter. The 75ft would be 7/8" hard line.

Most of the remote tuners (like LDG / MFJ) only have coax connections, so I assume I'd have to use a 4:1 balun?

Stay away from baluns--nothing but problems -- they are not this magic auto tuner or whatever hams think they are--they are instead power dissipators and failure points because they don't like reactance.

Those plastic radio autotuners are hammy low duty cycle boxes that will likely crap out with any kind of AM buzzard transmission at more than a few hundred watts.

In my opinion a remote bal.tuner would work okay in theory only because you are using LDF5-50 which has tolerably low loss into a matched load.  Otherwise (if you used some kind of inferior unbalanced line) you'd lose the benefit of open wire line, which is its extremely low loss with a high vswr on the line.  

So, you need a remote controlled balanced matching network.  The late John Bliss made such an animal (The Bliss Matchmaster) which consisted of motorized pair of roller inductors and motorized vacuum variable cap.  All in a weatherproof enclosure.   It was super expensive (by ham standards) -- I think he wanted around $2500 for one.  I only know of one ham who has one, Paul W9AC.  So, you'd have to, and probably want to, homebrew one.   You can actually simplify it by using one motor driving both cap and inductors (inductors on a common shaft) using different gear ratios so the cap turns twice as fast and the inductor (or maybe it is the other way around).  That's a trick I got from WB9DNZ.  

Isn't it a lot simpler though to just run the balanced line into the shack and right at the entrance, position some kind of manual tuner?    At one time, Bliss made and sold manual Matchmasters, and when I was newly back on the air and ignorant, I bought one.  A lot cheaper but still way more than a K1JJ supertuner    I think mine was around $800.  It basically followed the Rich Measures balanced tuner design.  That design, essentially paralleled L networks with a common cap is in my opinion, inferior to a link coupled design (Matchbox).  That's because you have a conductive path all the way from the parallel feed to the coax, so in an environment like mine, you see common mode junk on the unbalanced line that gets stopped at the link coupling in a Matchbox.   If you are out in the country and have room for spreading out your antennas this may not be a problem.  

Rob

[W4NEQ]

Here is Don's - K4KYV implementation of a remote antenna tuner located at the base of his tower:

http://amfone.net/Amforum/index.php?topic=30748.msg239573#msg239573

He uses it to tune the 127 foot tower on 160 & 80, and the owl fed dipole on top at 80 & 40 meters.

What is really clever is that he has it worked out to be remotely adjusted by a single motor driven shaft - kind of a one-knob tuner.

For a while he was using coax to the atu, but he recently converted it to (untuned) owl to the atu.  An untuned owl operates at its characteristic impedance.   This elaborate no-balun setup is very efficient.

Chris

[aa5wg]

For efficiency, home brew ladder line from antenna to link antenna coupler, located in the shack, is hard to beat.

Rob, K5UJ, is correct.  Tuners with baluns should be avoided.  Antenna tuners that are used for multi band or multi frequency with these components have stress related disorders such as: the balun can develop heat, a roller inductor can arc and a antenna switch or relay can arc.

The mechanically and electrically simple link antenna tuner combined with home brew ladder line is the proven way to go.

Chuck

[W2VW]

BalUns work fine when the rules are followed.

[W4NEQ]

Assuming you're feeding a multiband antenna over owl, expecting a wide range of resistance and reactance, and you're using a standard, ferrite core Ruthroff (Sevick term) 1:4 balun, how would you characterize the rules?

Chris

BalUns work fine when the rules are followed.

[W2VW]

Assuming you're feeding a multiband antenna over owl, expecting a wide range of resistance and reactance, and you're using a standard, ferrite core Ruthroff (Sevick term) 1:4 balun, how would you characterize the rules?

Chris

BalUns work fine when the rules are followed.

Place the BalUn before the section of the coupler which provides any conjugate match.

[w5omr]

The W7FG stuff works very well.  An enterprising ham could duplicate it, relatively inexpensively.
A roll of 14ga stranded copper wire and a $9.oo roll of black pvc sprinkler hose.

I had the honor of being the recipient of a few dozen of the pre-made spreaders.  That's how I knew what they were made of.  Spacing from hole-to-hole is 4.5".  I made a few out of the roll I got (need to find me some roundtuits to finish that project) by cutting 6" long pieces, measuring and marking the holes, a reasonably small drill bit, and a pair of healthy dikes to cut a 'V' to the hole.  Snap in the wire, and *presto* - 600-ohm open wire line.

If memory serves me, a G5RV is coax fed for an indeterminate length, broken out to open wire line for 50' to a dipole.

450-ohm Ladder line would suffice, if you had the stranded-wire type.  Solid core is hard as hell to work with, and in windy conditions, the crap will break in a heart-beat.

[W4NEQ]

Place the BalUn before the section of the coupler which provides any conjugate match.

Can't argue with that.

BUT most tuners have one at the output instead.  Too many of us, myself included, are guilty of correctly promoting the advantages of using tuned feeders for a multiband dipole, while poo-poo-ing ferrite balun interfacing with single ended tuners, and not suggesting a good alternative.  

Hi-Q link-coupling remains the most realistically efficient method, and that means a Johnson matchbox or homebrew, with perhaps a few odd others.  Floating and mirror designs suffer their own troubles.

This continues to be a puzzle.

Chris

[WA2SQQ]

If you are looking at a remote tuner, consider the ZS6BKW antenna. You would only need a tuner on 75 meters.

ZS6BKW's antenna is nothing more that a modified G5RV, both which play equally horrible on 75m. I built it and did side by side comparisons (with G5RV) on the air. Absolutely no difference between it and the G5RV. The ZS6 shortens the antenna element and lengthens the feed line. A tuner effectively makes the same changes. G5RV is a good 40M antenna, but on 75M, the SWR is off the scale. It's on 75 that I'm trying to do better. The tuner presents a good match to the transmitter, but I'm convinced that there is no substitute for a true resonant antenna.

This evening I figured out the two loading coils I'll need to put up a slightly shortened 75M dipole within the 95 ft. I have to work with. I'll leave the G5RV up and use it for 40M where it does a very good job.

[WA2SQQ]

For efficiency, home brew ladder line from antenna to link antenna coupler, located in the shack, is hard to beat.

No argument there ...
Unfortunately, the layout of my property dictates otherwise. My lot is 50 x 125. The tower (the highest point on the property) is located in front of the garage, just about half way down the depth. I need to feed the antenna from the tower, which gives me a nice slope to either end of the property. There really isn't any practical way to get OWL from the shack up to the tower.

I have two lengths of 7/8" to the base of the tower with two coaxial switches. Currently one is used for HF, and the other for VHF & UHF. Wish I had more room, or some high trees, but that's not the case. I think the answer to improving my 75M signal is going to be a dedicated 75m dipole, slightly shortened to 95 ft using two loading coils. Figured it out this evening. I'll make the two coils tomorrow and hopefully get it up by the weekend.

[KD6VXI]

http://www.torontosurplus.com/communications-equipment-military/harris-radio/harris-cu-938-c-urt-38-cu938-antenna-coupler.html

2 to 30 mhz, remote tuna, legal limit.

No price, though


Might be what you're looking for.  Says it will match a mobile whip to any of the freq's listed.

Ran across this while looking something else up.


--Shane
KD6VXI

[K5UJ]

Before you get wrapped up working out loading coils try putting up a full sized 1/2 w. dipole and letting around 20 feet on each end hang down.   I did that and got a 130 foot dipole on my 50 x 100 foot lot.  Simplicity....the less coils, traps, baluns, etc. the better.