The AM Forum

Here's a recent disussion I ran into and thought I would pass it on as a question:

What type of feedline do you use and why?? Coax? Ladderline? Homemade?

I found the subject rather interesting and have found a ton of topics on the internet, Everyone has their reasons, what works for you and why??

I have tried both this week.... Some interesting results to follow...........

#10 spaced 4 inches with Johnson spreaders. 250 foot dipole.
I prefer coax on the LPDA  gfz

I use balanced line (450 ohm Ladder-line) on my multi-band doublets.  I use coax on my yagis and  verticals.

I use 14 ga stranded 450 ohm ladderline with my 260' flat top dipole, but would like to switch to homebrew 600 ohm open wire feeders with about a 6" spacing. To me, the open wire feeders are the optimum feedline.

Whatever you do, try to keep everything "balanced", including a double balanced antenna tuner.

My tuner: http://members.aol.com/yardleyite/tuner.html

Just my two cents worth.........

Regards,
           Joe Cro N3IBX

I swear by 600 ohm open-wire transmission line. On a gamble a few years back, I bought the stuff that W7FG offers, and I have found it to be reliable, inexpensive, easy to work with, and it holds up well. Other users report similar positive experiences. Regardless of rain or snow, the impedance of this line remains essentially constant, unlike the 450 ohm glorified TV twin-lead. The only time I have to tweak the antenna matching network (other than when I QSY), is when there is appreciable ice build-up on the antenna and/or feedline. I would recommend the W7FG product to anyone, and it beats the hassle of having to fabricate 600 ohm open wire feeders yourself. It is also very lightweight, so it reduces the sag and loading on the span of a fairly long wire antenna.

I feed my 126' flat-top antenna/open-wire transmission line combination with a homebrew balanced-L network. Works great, and I can maintain a unity VSWR anywhere from 3.5 Mhz to the high end of the 10 meter band with no problem.

The only drawback to open-wire feeders is the need to achieve electrical balance in the line and antenna; this is  accomplished by maintaining the best possible physical symmetry in the installation, and by feeding the line with a source that provides nearly perfect balance between the two phases. I think that a balanced L-network can achieve this best. The routing of the feedline is critical in that it must be kept away (by at least 18 inches) from metallic structures, and like any type of feedline, should be run ideally at a right angle from the antenna proper.

As Mikey says, "Try it, you'll like it!".

73,

Bruce

^^  Second what Bruce sez.  The W7FG stuff is absolutely outstanding, is dirt cheap for what it is, converting to that from coass was the single biggest improvement I ever made to my station.

I have two 75 M flat tops fed with this stuff (one a fan dipole) and although the end ropes have broken, the W7FG has NEVER failed and handles high power with no problem at all.

To feed it into the shack I cut a piece of plexiglas to fit in the window, installed a could of banana jacks for "feedthrus", and just closed the window on the plexiglas.

Considering the time and materials you could never begin to make that feedline for what W7FG charges for the stuff.

Coax is fine for beams and verticals, but I would never consider anything but ladder line for feeding a balanced antenna (Dipole, inverted V, etc.) It just works so much better and enables easy multi band operation with a good tuna. Just be sure to pick stuff with heavy enough conductors to keep the I/R losses to a minimum.

                                                The Slab Bacon

I use 14ga. 450 ohm ladderline (from Davis RF)
on my ocf dipole for multi-band oper.
Virtually no wx related swr effects, as the ant. is insulated wire ;-)

Your mileage may vary...
tag, title tax, extra.

I've used both - coax and balanced open-wire. Both work the same, when used properly. The key thing is to make the length of your line, be it coax or open-wire, long enough to reach from your transmitter to your antenna. ;)

All kidding aside, it's all about tradeoffs. Coax is much simpler. There is no need to worry about nearby conductors, it is more easily passed through walls and such, rain and snow have no effect, and generally no tuner is needed. For this simplicity, you give up bandwidth (unless you use a tuner on a single band), there is no multiband capability (with exceptions like using a 40 meter dipole on 15 meters, etc), there is more loss in the line (only an issue on long runs), heavier line (may put more stress on the center of the dipole), and it is probably more expensive (generally coax is more expensive than ladder-line).

Open-wire feedline is a little more complex, mainly in that your need to use a tuner. I've never understood many people's seeming aversion to using a tuner since it is not much different than tuning a transmitter. Once you find the proper settings for each band, moving frequency/bands is pretty simple. But the added complexity gives you almost complete frequency independence/capability (given a proper tuner). This feature alone can be the best selling point for those who don't have space for multiple antennas.

Another thing to consider is a multiband coax-fed system of several dipoles. Here you have several dipoles, cut for various bands, on a common feedpoint. In this manner, you sort of get the best of both worlds, the simplicity of coax and multiband capability.

One final item in favor of open-wire feed is that you can use your 75 meter dipole on 160 meters. If you have space for a full-sized dipole on 160, this is not a big deal. But if you don't (and many don't, considering the amount of space needed), this is a BIG deal (no pun intended). The caveats are that you will need a good tuner - no parts can get hot when transmitting, so you will need a coil made of large conductor (copper tubing or similar) and preferably a higher-quality feedline. Ladder-line will work, but losses can be higher than desirable, especially on longer runs. So, something like open-wire line with larger conductor size (12 ga or larger) is preferred.

Good luck with your antenna project(s).

Hi Kevin,

There is not much more than I can add that the other illustrious folks before me have not shared, but I can relate a few of my experiences here at W1UJR.

First, W7FG line and antennas work great, they are inexpensive, and overall quite robust.
You'll see in the photo below that my location lacks any center support, and being fresh out of "skyhooks", I just let it dangle at the feedpoint.

The only problem I had with the stuff was a break near the lower feedpoint on the building.
This was caused by the antenna flexing in the wind, I mentioned the lack a center support, the wire "work hardened" and broke from fatigue. I simply cut and soldered it back together, liberally coated with self fusing tape for the repair. To prevent future problems I used the old loop and spring trick that is mentioned in the early ARRL handbooks. I can email a photo if that helps.

My feeling is that if you are not going to have multiple resonant antennas for each band, then balanced line is really the way to go. Yes its an old technology and a bit more of a challenge to run than coax, but it has low loss, works over a wide SWR, is inexpensive, and the coolest thing is that you can attach little neon bulbs to indicate your power level and balance. I use two of these at the feedpoint in the shack, and adjust for equal brilliance. The bulbs also flicker during keying, or modulation, serving as as very rough mod monitor.

I run my feedline through the barn siding using porcelain insulators and threaded rod, then down the inside wall, and connect to the Johnson Matchbox. I then use coax in the shack between the various RX and TX units.


W7FG Antenna and Feedline at W1UJR

(http://www.w1ujr.net/images/KW1I%20and%20NE1S%20160%20Meter%20Antenna%20Installation4.JPG)

...homebrew ladder line...spaced 5 inches...werks fb...i used 1/2 inch pvc pipe, cut at 6 inches...12 ga wire...never a problem....sk..

Hey Joe,
How much L do you end up using on 160 with that tuner. I only have 22 uh inductors and could use a little more L. Todd KAQ will tell you my tuner is too ugly for pictures.  gfz

I think that you should build a treehouse hamshack and bring the two ends right into the shack and attach them directly to the tuner

WU2D Mike  8)

Any of the ladder lines are so easy to get along with. No problems ever with the 450 ohm window line. Open ladder line can handle very high SWR without a tremendous amount of loss. Great for the untuned dipole and multiband use with a heavy duty low loss balanced tuner.
I cut a 2 inch hole through some 2X6 or 4X6 and used a PVC pipe to get the ladder line into the basement where the K1JJ tuner is mounted on the cinder block wall, about 5 feet from the hole.
Running open ladder line in through the basement across house wires and Flourescent fixtures, about 50 feet, caused major problems and a lot more noise pickup.
Fred

I have never used coax to directly feed a dipole.  When I first started with my novice rig, I used 72-ohm TV twinlead.  It was about half the size of the smallest size zip cord, but it worked well - until I tried to run more than about 100 watts input.

Then I went to open wire line.  I have used a number of varieties, from the 450-ohm open wire TV  stuff (#18 copperweld with 1" plastic spreaders spaced every 6 inches or so), to homebrew using plexiglas rods, polystyrene rods and  ceramic spacers, with everything from 1" to 6" spacing. It all worked about the same for me, but the UV quickly disintegrated the polystyrene rods.

I prefer to put all my effort into one good solid dipole that will work multiple bands and work across any band with uniform efficiency, than to have a rat's nest of self-resonant dipoles strung all over the place, plus the separate dipoles can be expected to all interact to a certain extent. With the open wire line, I never worried about SWR - just tuned for maximum coupling to the transmitter and highest reading on the thermocouple rf ammeter.

My present dipole and open wire feeders are made of #10 copperweld, salvaged from abandoned telegraph lines that ran along the train tracks.  Part of it uses 2" Johnson ceramic spacers, and the part that goes up the tower uses a spacer made from a plexiglas strip, every 10 feet, running up inside the tower, with the spacers attached to tower rungs, and tension on the wires maintained with turnbuckles.  I use buried coax for the 140' run from the transmitter to the tuners at the  base of the tower, but have contemplated relocating the tuners in the shack and running open wire line all the way to the tower so I don't have to go out to the tower to change bands or make large excursions within a band.

I also use the same coax line to directly feed the 160m vertical through an L-network at the base of the tower.  Many older broadcast installations used 5-wire open wire feeders to simulate a coax line, which probably has lower loss than RG-213.

Even when feeding with coax, I don't worry too much about SWR if it is less than about 2.5:1.

The simple answer is: yes!  ;)

Using a balanced feed to a balanced ant gives you much more flexibility, as others have stated already. An open line can become part of the antenna in a way that coax can't.

That's not all there is to it, though; there's the question of how you arrive at a balanced feed, how your balanced line is run, and what kind of antenna you're feeding. Different scenarios call for different solutions.

Personally, I prefer to run coax from the shack to a link-coupled tuner at the feedpoint of a balanced line dropping straight down from the ant. This gives you several advantages: you can mitigate in-house RF issues like what Fred was describing, your balanced feedline can be one straight-down drop (so there are no parallel runs to cause imbalance), and you can dial in the perfect impedance transformation with the tuner (unlike a balun). The use of a link-coupled tuner also leaves your antenna floating for DC, which can be handy if your ant likes to take a charge from nearby lightning strikes.

On the downside, you need to take a walk to the ant to change bands, and are better off taking that same walk if you want to make a large band excursion.

My 200' flat-top is fed this way, with 35' of 420 ohm black window crap dropping straight down from the ant to the tuner. The tuner is fed by 120' of RG-11 (yes, I know that's 72 ohm line) straight from the transmitter.

With the tuner set for a flat match at 3885, I can still tune the transmitter for 3710 quite happily. The only caveat there is that if I don't retune the ant, impedance shifts caused by weather changes will manifest themselves at the transmitter much more readily than if I retune. I was on 3710 with the ant tuned for 3885 the other night when a quick passing shower caused my plate current to jump up 50 mA in 20 seconds. On that same frequency, with the ant properly tuned, there's hardly any weather-induced change at all.

In short, you're far better off with coax in your shack, and far better off with a balanced line feeding your ant (in most cases, depending on the ant). How you get from one to the other is up to you.

My $0.02.

--Thom
Keep Away One Zorched Ground Conductor

Mike,
      Good thinking OM! The real trick is to figger out the right amount of open wire line, nix on the tuna, and toon out the reactance with your link coupled tank circut in your transmitter!

I can (fortunately) do that with some of my more oldbuzzardly rigs for 75M.

Best Regards and hope your treehouse/hamshack is a double balanced treehouse/hamshack!

Joe Cro N3IBX

I look forward to using open wire feeders someday, been amassing the insulators, feed thrus, and other hardware for years. The current location doesn't lend itself to it, between the radio room location, twists and turns to reach the antenna out back, metal standing seam roofing on a portion of the back roof and so on.

The good points have been made by others. Coax is easier and more practical in cases like mine, but if you have a clean shot from your radio room, go for the open wire. Along with enhanced utility, the coolness factor is very high.  ;)

What does Todd, KAQ know about tunerasthetics anyway? Come on Todd, 'fess up OM! I personally think my tuna is about as fugly as a tuna gets, but it works well. It's what's inside that counts (That's what I keep telling the yl anyway).

On a more serios note, I use a pair of 40Mh rollers inductors in tandem. I calculated that I could probably get away with something like 26Mh on 160M, but occasionally I like to go to the bottom of the band to work CW. I use approx 5/8 to 3/4 of my L on 1885KC. My antenna is a 260' flat top dipole that has seen better days. I feed it with about 100' of 14 ga 450 ohm ladderline. The large breadslicer type variable cap I use in my tuner is 400pf. I've padded it with about 100pf of C in the beginning, and then realized I really didn't need the additional capacitance, and just wound up using the standard breadslicer without any padder caps.

It seems that lower my antenna hangs, the more L I need to get it to resonate on 160M. Right now it's only up at about 35-40 Ft. or so, but it was up at 75' a few years ago. Countless storms causing it to blow down, and a deteriorating physical condition have prevented me from hanging it up at it's original height. This will however change since my knee operation!

I hope this info helps. If you have any more questions, please ask.

It seems the lower the antenna height, the more dependent it is on L, regardless of the band in question.

Very best Regards,
                        Joe Cro N3IBX    

I know that Frank's tuna looks like something out of a Frankenstein movie. In fact, much of his radio room does! Some of the knobs are bigger than your average steering wheel. Cap'n Nemo would be proud. ;)

I also know that my Johnson Flashbox really does flash, a purty blue color!


They have pills available now to help that, Joe! Instead of L, add some V or C.  ;D

Joe,
That sounds really accurate. At 22 UH I run a bit more than 400 pf but feed line a bit longer. I use 2 300 pf cardwells in parallel with 1/4 inch spacing. TNX om.

Todd,
there is flash box on top of the tuner just in case I blow it up. Maybe I should send Joe a picture of a ugly tuna.

Frank,
        I'd love to see it, and can speak for many others as well. Is there any way you could post a pic or two of it to the BBS?

The uglier they are, the better they work!

Best Regards,
                  Joe N3IBX

OK Joe,
I just sent you 3 pictures for a laugh. You can post them here if you want.

Anyone using any sort of lighning arrestors on their system?  Polyphasers or I.C.E. on coax?  Spark plugs or grounding knife switches on ladder line? High impedance choke loops? Static drain chokes or resistors on coax? ARRL equipment insurance in lieu of lighning protection?

I try to bring everything down to coax before it enters the house at a grounded metal input panel with polyphasers.  Have ceramic feed-thru on the panel for an inside tuner for the inverted -L with outside disconnect/grounding switch.

A wonderfull topic!!

I like both and have found that ladder line to be the most frequency agile when used with a good link-coupled antenna tuner and a 160 meter center fed dipole. Best part if used with a 160 meter dipole you will find substantial gain lobes at the higher frequencies.

If you use ladder line beware of the feed-line lengths to avoid high voltage points at the tuner. For example, on 160 I would avoid even multiple of a quarter-wave.

Coax provides the simplest approach for most hams. Ease of installation, no sensitivity to placement near metal object; allows for simple chokes to be constructed by wrapping multiple turns at the feedpoint etc. Any length can generally be used without high voltage points at the tuner.

My ugly Tina Tuner:

http://home.comcast.net/~w1ia/

Brent W1IA

I use a big-ass military surplus knife switch here at W2XR where the 600 ohm open-wire feeder immediately enters the basement. This switch is connected thru a heavy gauge copper grounding strap that goes directly to a ground rod located just outside of the house. When the station is not in use, the switch is of course thrown to the "grounded" position. Unrelated to this thread, I also open the 120 and 220 VAC circuit breakers that supply prime power to the shack, when it is not in use.

I used a piece of 1/4-inch thk Plexiglas to replace one of the basement windows where the 600 ohm feeder enters the basement; this Plexiglas was drilled to accomodate a pair of porcelain bowl-type feed-thrus, and this makes for a very neat and clean entry point. I also fitted weatherstripping around the perimeter of the Plexiglas window to provide for a tight weatherproof seal. The homebrew balanced-L tuning network that makes the transition from 50 ohm coax to the balanced 600 ohm open-wire transmission line is located about 5 feet from the entry point into the basement. This provides for a minor nuisance, as the shack is about 20 feet from the tuning network; you have to get up, and walk across the basement and tune it anytime you QSY. But it does beat those installations where the locally-tuned ATU is located out-of-doors and an appreciable distance from the operating position.

I don't believe that Polyphaser, et al, make a lightning arrester designed for use with open-wire transmission line. I have seen the website of one enterprising ham who did use a pair of conventional automotive spark plugs as lightning arrestors for use with his open-wire feeders.

Just my 2 cents worth.

To quote the title of a very old QST (or maybe it was CQ Magazine) article; Open Wire Feeders Forever!!

73,

Bruce

Good question, a real issue if you've got balanced line feeding right into the housing. Some hams just disconnect this from the outside when a storm threatens, and throw the feedline away from the house. Simple and it works, if you are home to do it. I had a nasty experience with a lighting strike last year, so did some research. My take on the Polyphaser or spark plug/arc systems is that  it only makes a difference on static discharge for storms, or nearby local strikes. A direct hit is almost sure to get you, no matter what system you have in place. The tremendous amount of energy that is required to jump 5,000 feet to the ground is going to ignore the 1/8" gap on the spark plug, and likely vaporize any of the lighter Polyphaser gear.

With that said, its a very good idea to protect against static buildup during a storm. A few years back I was at my office hamshack during a nearby storm, and kept hearing a snapping noise. I looked up, and saw an arc between the two metal antenna feed-through bolts, snap, snap a few moment before I heard the thunder! Shocked me, the metal rods were at least 4-6" apart, imagine what that would do with a ricebox connected to the antenna. Even a tube rig would likely sustain damage to its RF coils.

In my experience, for nearby strikes, yes, do what you can to mitigate them, as for direct hits, your pretty much done.
See the photos below of a strike sustained at W1UJR last July.
Spilt a 100 foot tall pine tree from top to bottom, and blew out a number of electrical items in the station and house.
http://www.w1ujr.net/lighting_strike.htm

(http://www.w1ujr.net/lighting/July%2011%202006%20Lighting%20Strike%2018.jpg) (http://www.w1ujr.net/lighting/July%2011%202006%20Lighting%20Strike%2006.jpg)

That's just my 2 cents Sonny.  ;D

Hmmmm..... I'm cornfuze Tina.

A dipole, let's use ur 160 story see'ins that's where I'm headed, at optimum hieight feeds at about 72 ohms. Low voltage high current point. At lower heights it's lower. For instance, EZNEC says my future dipole at 80 feet hi dipolio will be 30.5+8j Z. Pretty Low.

 Now, wouldn't a 1/2 wave feeder (even multiple of 1/4 wave,180 degrees) show the same -Z at the tuner ?? (-Z indicates the phase shift.) And wouldn't this appear at EVERY half wavelenth along the line whether even our odd ?? (I know there are other effects of the even 1/2 wave but we'll ignore them for the sake of this discussion).

And if so, a half wave feeder would be what you want to keep the voltage off the tuna.
Am I thinking wrong here ? Remember, I'm just a buddly  :D

Here is my grounding knife switch on my balance feedline.
I have replaced the connecting wire shown in this picture with a larger gauge.

(http://home.comcast.net/~w1qwt/images/chgovr.jpg)

The balanced tuner, 450 ohm feedline, and 75 meter dipole allow me to operate on
160 - 6 meters. The 3/8 inch pipe goes down 5 feet to a 6 foot diameter copper ring of pipe in the
ground. It is like a spoke assembly on a wheel the center of which is a 6 foot ground rod.

On my coax fed antennas I use polyphasers for lightning protection.

Regards
Q, W1QWT

The nice thing about using a link tuner is you can ground the center of the antenna side coil for static drainage. This won't provide lightning protection on the order of physically disconnecting the feeders, but it's better than having the antenna floating.

IIRC TrueBruce, it's one of the ART-13 switches? They come in single, double, or triple pole configurations. Those are excellent for that purpose, along with the old copper electrical types you saw at my place on the 'Wall of Knives' and in the garage. Not only do they work well, allowing you to switch the ant to ground when not in use, they add to the Frankenstein look of the station.  If you gap it ever so slightly from ground as a storm approaches, you can see little zorches occur. :D


Glad to see I'm not completely out of touch for using the 'feeders' term. Still recall several SKs telling me to use  'Balanced Feeders' or Open wire feeders with one ant for all HF bands. Never did it, but I still remember.

Along the lines of the spark plug approach is the old 'horn' approach, using pieces of formed aluminum tubing bent just so, and adjusted to a small gap from the feed thru bowls to ground. Collins has a diagram in some of their transmitter manuals complete with measurements, I've also seen them at BC stations and elsewhere. 

When I go away I lay a couple pipes over the feed line pulling it to the ground.
Bruce I have pretty much the same set up with the basement window but just drilled a couple holes for the feeders to pass through. A spark plug will flash over at a low voltage. Remember the old handbook articles with a spark gap made from copper cut to a point. I have an old telegraph spark gap. that I modified.

Enclosed are a few pics of Frank, WA1GFZ's "fugly but beautiful" tuner. I think everyone would agree that it's what's inside that counts!

Mod-U-Later,
                 Joe Cro N3IBX




http://s50.photobucket.com/albums/f338/n3ibx/?action=view&current=gfztuna.jpg

http://s50.photobucket.com/albums/f338/n3ibx/?action-view&current=gfztuna2.jpg


http://s50.photobucket.com/albums/f338/n3ibx/?action=view&current=gfztuna3.jpg

Dislexia gets me again BUddly...ArrgH!
ass-backwards...sorry

Brent

Single line feed, " the other white feed, not often seen in better amateur circles."

My arguably 'best' or should I say most used antenna is a somewhat random length windom 138 ft. (total) fed 30 ft. off center with an approximately 50 ft. length of single line feeder from a rotary coil/cap "L" network.  The dimensions were defined by tree distances and in no way represent much of a decent plan.

 So I guess, not counting the 6' or so coax feeding the "L" net tuner up on the basement windowsill, that it's not a balanced feed or coax fed antenna.  It's a single line radiator right out of the shack.

You don't want to look too closely at the MMANA (JE3HTT's) plots for this antenna too closely. - All over the place, but that's what makes it interesting.  Seems to work fine most of the time.

A/C MMANA, on 160 & 80 I'm loading up the vertical feeder and using the whole top as a capacity hat and on higher freqs, the horizontal element seems to be the radiator.  Ground? Outside the window to a couple of ground rods. Also my E service is buried for a distance of of 200' or so.  I think that's my 160 ground : )

Yeah, there're also 40 and 20 meter dipoles here but rarely used.  Come to think of it, much of my stuff is rarely used.  Gotta get on the air more.

Gonna try some stuff from w7fg , with a Palstar Balanced tuner, The Coax Fed 75 Meter antenna at 90' seems to be beating out the 450 Ohm ladderline antenna ... It's a pain to swap antennas out, BUT , I wanted to know the difference from this particular QTH...

I was surprised to see the coax stuff beat out the other... I am going to try one of w7fg's set-ups probably and see what the difference is.

The Coax fed antenna is done with LMR-400 , DX-Engineering Current Balun, The 450 Ohm Ladderline antenna is done with the obvious and a Palstar Balanced Line Tuner with L/Network ...

Both Antenna's cut same length and hung in the same configuration, I did not expect too see what I have for results, Now we will see what will happen with true Open wire feedline.

The 450 Ohm stuff SUCKS in the rain too by the way...


'73's, More results later on!

I have been using the 450 ohm feedline for a number of years now and I don't
notice any problem when it rains other than the tuning points may be slightly
different. Currents are still balanced and signal reports are fine.

Regards
Q, W1QWT

I'll have to get your version of 450 ohm, this stuff I am using is terrible in the rain. Probably some cheap junk I picked up I am sure, Knowing my luck.

I think I bought it from wireman.
Maybe in some installations it is more susceptible to moisture?
I remember that when I was in the Navy when we were at sea in a bad storm
some of the antennas would tune up differently than when they were dry and
other antennas didn't seem to be affected. We had both wire antennas and vertical pole types. Unless the atmospherics were bad we could still contact land however.

Reminds me of a funny story. There was one antenna that suddenly became very hard to load into. I took a stroll back to the fantail to see if that vertical was still there.
Sometimes in a bad storm they would snap.
Seems somebody decided to run a wire clothes line from it to the life rail and used metal wire. Flapping from the clothes line were sailors skivies!
I have heard people say you can load up a bedspring but underwear?

This was a submarine tender so the fantail could not be seen from the bridge
so the officers never saw it.







Regards
Q,
W1QWT

You must have some really crappy stuff. I have been using the 14Ga crappy brown stuff for years with no problems in the rain.

It may take a slight retweak of the tuna, but thats about it. I do have to retune slightly when its coverd with ice, but thats about it.

If you are experiencing a lesser performance with your balenced feedline, you may want to take a closer look at your tuna. Also make sure you are using the heavier stuff and not the wimpy 16 or 18Ga stuff.
the thinner guage stuff can exhibit some I/R losses when ran at a low impedance for a long run.

                                              The Slab Bacon

Try not to use the floppy solid conductor ladder line for long term installations. This usually has 18 ga copperweld that fractures inside the insulation after a short period of flapping in the breeze. The rectification that usually occurs at the breaks will make you think your receivers have all developed image problems and will make you go nuts trying to track it down. It also tunes strangely and can create spurious emissions galore. I used the stranded 14 ga stuff for years with no problems but currently use 10 ga flexweave homebrew line.
Skip

This stuff was stranded 14Ga... And the tuner is a Palstar BT1500A ... I really don't think it's the tuner. It only did it in the rain storms we had this week.

I run on a small bandwidth, I am not concerned about bouncing all around the bands, Just putting a good signal out on 2 of them as efficiently as I can.

Kevin,
        I have never heard of or seen a "Palstar" tuna. If it was created for the ssb / ricebox groups, it may well not handle the duty cycle of high powered AM. My tuna is homebrew, it will handle anything that you can throw at it.

For the hell of it, make a long "old buzzard" transmission at your highest power level. After you unkey, lay your hand on the top of it and see if it is getting warm. If it is, you know where your power is going. If it is getting hot, it is dissapating some of your power. (that which is heating the tuna is not going to the antenner). I have seen many tunas rated for "legal limit" power melt down with well less than "legal limit" AM power levels. Here is a good opportunity for a little home brewing!!

                                                   The Slab Bacon

Also, what I forgot to mention is that you will really see the advantages of the ladda line vs coass is when you try to use the antenner on a band / frequency OTHER than what it was cut for.

Losses should be pretty close when the antenna is a 50 ohm match. But as the antenna's impedance goes up (longer antenna @ higher frequency) is really where you will start to see the ladder line out perform the coass.

                                                         The Slab Bacon

I gotz the w7fart gas stuff comin soon.

An I got a bigassed ol Gonset leenyar in my garage waitin for the right time  ;D

Some good info on wet ladder line losses below.

http://www.vk1od.net/G5RV/
http://www.ocarc.ca/coax.htm
http://users.triconet.org/wesandlinda/ladder_line.pdf



And the spark plug based arc gap design some one asked about previously is at

http://www.athensarc.org/ladder.asp

Probably not as prevalent a change on say 40m and up, where 1 1/4 wave is only 30~35 feet (depending on soil conditions).

But, lower in frequency, it makes sense that you'd probably need more critical L tuning, as you'll have more C between the antenna and earth.  The more C you have, the less L you need.  This might be why the NVIS antennas seem to work... inductive reactance (X_L) is nearly 0 and you'll need more capacitance to tune say, a 160m antenna, that's only 30' off of the ground.

To answer the poll, I noticed the most -marked- dramatic difference when I changed my Inverted Vee feed-line from 50Ω coax to 450Ω ladder line.  Then, I closed up the bottom of the inverted vee with another 120' of wire (since I was now using an impedance matching device anyway) and created a full-wave delta loop.

I'm constantly told that the mere 100w I run (according to the meters and gauges) sounds like other stations that are running 300w or better, with better-than-average audio.

Well, of course they say that, because you're big and scary Geoff. They don't want you dropping a 610 on them.   ;D

I'm told you're no small fry yerself, Todd. 

We'll have to get into a 'belly bumping' contest when we do get to eyeball each other

;-)

Now that is REALLY cool. You new antenna improved your audio too!

That's quite a message!

You've got me by about 80 lbs and an inch. I haven't yet developed a 'belly', too busy with other stuff. Work is progressing on the pod though, a.k.a. the ToddPod. There's still a ways to go.


No, bumping is out. I've been told that my brains are down in that region, and I don't want to suffer a concussion.

Steve was making a 'funny', poking at me about my writing style (or lack thereof).

That was just what commonly comes along with the report.  Since moving to Ladder line and the Delta Loop, instead of coax and an inverted vee, the signals reports from towards the north of Texas (day-light hour QSO's) have been consistently better than what I used to get.

Looking forward to tonight, when I'm gonna slide the rig down below 3.800 and see if ol' Todd is paying attention.

Todd!  Yer only 6'2" and 220?

Yer a WIMP!

;-)

I dunno about that, but damn, wouldn't it be fun trying?

 ;D

Good point! Makes any audio a more enjoyable listen.

That's some good reading.. Thanks for passing that along.

http://www.eham.net/reviews/detail/4517 (http://www.eham.net/reviews/detail/4517)

http://www.palstar.com/qstAT1500bal.pdf (http://www.palstar.com/qstAT1500bal.pdf)

I based my buy on these 2 articles/reviews... I work 21-28 days straight at a clip owning my own trucking buisness, I barely have enough time/energy these days to do much but enjoy what I do have, so find myself relying on store bought products for now. Once things slow down a bit I will have more time for brewing/tinkering.

The tuner would not be adequate for the "Big Strappers" but 1500 watts it will handle without trouble, It holds it steady on the dry days, Just wanders when it's wet out, leading me to believe it is indeed the 450Ohm stuff getting wet and the swr varying..

For sure. The tuner is not the problem.