View Full Version : LDG 4:1 BALUN, can I use it to run random wire?

02-01-2008, 03:47 AM
Still learning, so help me out...

When I look at the back of several ATUs, I see (besides coax) a balanced feed and a wire feed, and you jumper to run balanced... or something like that. I dont have a multi port tuner right now..

Anyway, I do have the LDG Z-100 and the LDG 4:1 BALUN.

Can I use the BALUN to run a random wire antenna? If so, how do I go about hooking the BALUN up to the wire?

Thanks for help-

02-01-2008, 03:52 AM
Google just answered my question...

http://www.ldgelectronics.com/manuals/RBAManual.pdf (http://www.ldgelectronics.com/manuals/RBAManual.pdf)


02-01-2008, 07:47 PM
Well, I just knocked the ice off the wire and redid a few things today, lost power for about 3 hours due to ice storm. Hams... what can you do with 'em?

Anyway, I strung up 60 ft of #14 insulated, ran it back to my LDG 4:1 balun, the n grounded it to a ground rod, came in and didnt expect much... BUT, the LDG Z-100 tunes up 160m to 10m all with 1.5 or less SWR. Now if I can just get a reply to my CQ I can get a signal report.

Anyway, the point is... 1 wire, if it is black insulator, is dang near invisible (unless you have ice on it) and works! How well I cant comment, but.. I expect it will yield good signal reports.


02-01-2008, 08:06 PM
Should do fine. I know someone who's using 33' of magnet wire, and he works all over on 75m.

And, yes, wires up in trees are next to invisible. In the past I've used #16 stranded, and with that, I actually had to find the feedline first and follow it up to find the antenna!

Good luck and have fun!

02-01-2008, 08:18 PM
Your antenna should work well from 40m up. With an end fed wire how well it radiates is very dependent on the efficiency of your ground system. Also, ditch the Balun. It's not helping and may even be hurting you by dissapating energy. An end fed wire is not a balanced antenna so there is absolutely no need for a Balun.

The only reason LDG recomends a Balun is that the tuning range of the tuner is only 6-800 ohms ( which is no better than most built in auto tuners) and up to 1000 ohms with a Balun. Trouble is, under mismatch conditions the Balun dissapates energy (it gets warm) and you loose efficiency.

By far the best tuner for a siple random length end fed wire is the L-network. Using a single inductor and variable capacitor mounted on a piece of wood you can build a matching network that will far outperform your auto tuner. These parts can be gotten at any hamfest and assembled in 5 minutes. Of course, you'll have to adjust it yourself.

02-02-2008, 06:57 AM
With a random wire you should use an UNUN. Do a web search on "unun" you will find discussions from basic to advanced.

02-02-2008, 11:23 AM
Do I actually have an Inverted-L?? Ill check Cebik and also look for a response here...


02-02-2008, 11:54 AM
The ARRL Antenna Chapter 26 page 15 shows the layout for a 1:4 till 1:16 Unun very well suited to bring a longwires impedance down to accomodate atu's. I use it on my saling boat to help my Yaesu FC40 atu which has a rather narrow range (15-600 ohms I believe).
Building this unun does work with smaller 1.5 inch powder-iron toro´dsbut then you would need rather small diameter wire to be able to get minimum of 12 quadrifillar windings on it.
I have now built it on an Amidon T300-2 IP core (permeability 10) , 14 quadrifillar windings of 1.2mm diameter teflon covered wire.
You can choose the 1:4, 1:9 or 1:16 connnector to find the right ratio to help your tuner.
It can of course also be used in the opposite direction when wanting to tune a very short wire (far shorter than 1/4 wavelength) that shwos a very low impedance (eg short wire for 160m).
I did wire the unun differnetly than the schematic shown, based on extra insights from another ARRL publication on baluns and ununs.
Mail me if you want extra info (check my callsign)

02-02-2008, 12:02 PM
ZTT - EOF, thx for the information, I will research that more.


02-02-2008, 12:52 PM
From the best I can tell, I have installed a 70 ft sloping Inverted-L, and many articles are showing either direct feed or 4:1 BALUN.

The LDG Z-100 tuner is tuning 160 - 10, and 160 is plenty workable. My first 160 contact was just last night, we exchanged 55 RST- noise floor was 59. So, it evidently works, Ill keep it up and evaluate it more. I did do an 80 and 40 contact last night also, CQ for a true signal report came back 59 and was heard 59.


02-02-2008, 05:03 PM
Andrew, weather the wire is in the shape of an inverted L, or straight, or shaped like a zig zag makes absolutely no difference to the fact that an end fed antenna is not a balanced antenna. A loop or a dipole are inherently balanced because the current distribution in the conductors is equal.

I too have seen lots of bad information out on the web. The LDG tuner you are using has a very narrow tuning range, 6 to 800 ohms. Most tuners will cover 10 or 12 to well over 5,000 ohms. By connecting a Balun all your doing is introducing loss in your system.

02-02-2008, 05:29 PM
DPO, Ill stop by the local CB shack and pick up an SO-239 chassis mount, fix a board with it and direct feed the wire. I am guessing it will load FB, the same setup in my 20m GP also worked on 80 and below when I put a 33ft wire on it for the radiator.

Thanks for the additional details-

I will have this posted on my website as an article when I get done.

02-03-2008, 10:57 PM
Nope, that dont work, dont work at ALL! The only band that would tune direct feed was 30m, everything else was LOUSY SWR, would NOT even do 160 or 80.

I put the 4:1 BALUN back, tunes ALL BANDS 160- 10.

I worked a few stations the last few days with the BALUN config, and am very happy with the reports so, the BALUN stays.


02-04-2008, 12:19 AM
I have the LDG 4:1 balun, but I am using it to feed a balanced doublet. The antenna is 200 feet long, fed with ladder line.

However, I did use it on an end-fed random wire of about 85 feet. The antenna loaded fine on all bands 80 through 10 (with some increase in SWR on 30 meters) but appeared to be more like a dummy load. It was noisy on receive.

The problem with the LDG balun, the 4:1 version, is it does require an excellent ground. I an in the desert with dry, rocky soil, and a ground is very difficult to obtain. However, it will work if you can get a good ground. I operated portable last year for Field Day, using the same 4:1 balun and an inverted L, and I had a power company/telephone ground system. The antenna worked well. The balun was right beside the radio, so I was able to check for heat and there was none. Of course I was running only 100 watts. I believe the balun is rated at 125 watts.

The LDG 4:1 balun is *intended* to be used to feed a single wire. The manual on it shows how to use it for that purpose, but they do not explain the need for a top notch ground.

I use the LDG AT100Pro tuner with the balun, with very good results, but I have not tried it on 160 meters. As noted, though, I am now using the balun to feed a balanced line, so the ground is not required.


02-04-2008, 01:04 AM
I more or less, withholding wire length, put the sloper up EXACTLY as it was diagrammed in the LDG balun manual, about 10 inches from the balun (pix to come) it is grounded to a ground rod abt 5 ft in the ground.. ground (had to say it one more time).

It is working BETTER than my doublet.

Its a keeper for me.


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