Antenna Tuner Help Please

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#1
I am setting up a 27’ zerofive vertical antenna in an RV park. My little LDG AT-100Pro is not doing the best job tuning tuning this antenna and I am not even certain it is operating properly (it was given to me).

So, I am looking for suggestions - manual or auto, remote or in shack - that will do the best job possible.

Also, I‘m running an older IC-735 in my RV so I do not have a “tune” button on the transceiver. This being the case, how would one tune a remote tuner from in the shack??

My hearty thank you for any help provided. Anxious to get on the air!
 
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#2
A ZeroFive vertical usually has a 4:1 type balun at the base and needs lots of ground radials with a tuner in the shack. With everything working perfect its a very mediocre antenna at best using the supplied balun.

The very best thing to do is ditch the balun and use a wide range auto tuner right at the base with plenty of radials, then the antenna will wake up and work everywhere just fine. If your Icom had a tune button a good tuner would be the Icom AH-4, but I don't know how your radio would deal with that.

Otherwise an SGC-230, 231 or 237 series would work fine and you would just key up in AM mode or low power FM while watching your SWR meter, when it settles down your good to talk.

I have a similar antenna, the DX Engineering 43ft that also came with a 4:1 balun. It was a dog until I replaced the balun with an SGC tuner and then it came alive and worked great. I also played with different amounts of ground radials and going from four to eight to a dozen then finally about 30 really helped. All my radials are about 30-33ft long.
prcguy

I am setting up a 27’ zerofive vertical antenna in an RV park. My little LDG AT-100Pro is not doing the best job tuning tuning this antenna and I am not even certain it is operating properly (it was given to me).

So, I am looking for suggestions - manual or auto, remote or in shack - that will do the best job possible.

Also, I‘m running an older IC-735 in my RV so I do not have a “tune” button on the transceiver. This being the case, how would one tune a remote tuner from in the shack??

My hearty thank you for any help provided. Anxious to get on the air!
 
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#3
Zerofive

A ZeroFive vertical usually has a 4:1 type balun at the base and needs lots of ground radials with a tuner in the shack. With everything working perfect its a very mediocre antenna at best using the supplied balun.

The very best thing to do is ditch the balun and use a wide range auto tuner right at the base with plenty of radials, then the antenna will wake up and work everywhere just fine. If your Icom had a tune button a good tuner would be the Icom AH-4, but I don't know how your radio would deal with that.

Otherwise an SGC-230, 231 or 237 series would work fine and you would just key up in AM mode or low power FM while watching your SWR meter, when it settles down your good to talk.

I have a similar antenna, the DX Engineering 43ft that also came with a 4:1 balun. It was a dog until I replaced the balun with an SGC tuner and then it came alive and worked great. I also played with different amounts of ground radials and going from four to eight to a dozen then finally about 30 really helped. All my radials are about 30-33ft long.
prcguy
Thanks. I bought this presumably “no radial” vertical for specific RV park use (where I have no space for radials). So, I may well be flat out of luck with this unit. Zerofive says “no radials” but admits that all verticals work best with appropriate radials. I had at least hope I could get on the air - even if not with optimum performance.
So do you believe my current LDG AT-100Pro should tune this as it sits? I would get a remote tuner (like the SGC or LDG) if it would do better without radials than the current in shack LDG AT100Pro.
 
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#4
If your tuner is working correctly, use it in the automatic mode. Make sure you have a 12 volt
power source connected to the tuner.
When you transmit, the tuner senses the anrenna swr and adjusts it self for lowest swr.
It is always better to have the tuner at the base of the antenna, but the tuner must be in a
water proof enclosure. If not, put the tuner in the shack...
Make sure you have some ground radials connected to the ground, (lower side) of the base of
the antenna. The more radials you have, the better it will work.
Good luck
 

W9BU

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#5
From the instruction sheet for that antenna: "Even though this is a no radial vertical, radials are recommended for the best performance with any vertical."

I have that exact antenna. I am feeding it with an Icom AH-4 remote tuner mounted at the base of the antenna. I have about 16 33-foot radials laid out and I plan to add more. The antenna works well, for a vertical, and has allowed me to make many contacts, mostly on RTTY. I tried it once with an LDG AT-series tuner inside the house, but it did not work nearly as well as it did with the remote tuner.
 
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#6
So.......

From the instruction sheet for that antenna: "Even though this is a no radial vertical, radials are recommended for the best performance with any vertical."

I have that exact antenna. I am feeding it with an Icom AH-4 remote tuner mounted at the base of the antenna. I have about 16 33-foot radials laid out and I plan to add more. The antenna works well, for a vertical, and has allowed me to make many contacts, mostly on RTTY. I tried it once with an LDG AT-series tuner inside the house, but it did not work nearly as well as it did with the remote tuner.

Thank you.
Perhaps I’ll spring for a remote tuner. Did you leave the unun in place?
If I can only get a few radials down (perhaps), is that any better than none?
 
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#7
Your LDG tuner at the radio end should tune it to a usable match, but there will be a lot of loss in the balun and coax, that's just how that works. LDG tuners are not really meant for use right at a whip type antenna, they are more of a coax "line flattener". If you look at auto tuners designed for use on a whip or long wire the components are rated at much higher voltages than LDG uses because a random length wire or whip can have some wild impedance and very high voltage at the feedpoint.

Using your tuner at the radio end with the stock balun at the antenna and no radials makes a pretty grim antenna. It might make some contacts on the higher bands like 20 or 17m but not on 40 or 80. Put a bunch of radials or a couple of lengths of chicken wire under it and it will work much better. Put an SGC or similar wire/whip tuner on it with some radials and you won't recognize the antenna any more, it will impress you.

Does your RV have a metal skin? If so its commont to mount verticals to them and use the vehicle as the ground plane or counterpoise. You would still need an autotuner at the base of the antenna to make it sing.
prcguy

Thanks. I bought this presumably “no radial” vertical for specific RV park use (where I have no space for radials). So, I may well be flat out of luck with this unit. Zerofive says “no radials” but admits that all verticals work best with appropriate radials. I had at least hope I could get on the air - even if not with optimum performance.
So do you believe my current LDG AT-100Pro should tune this as it sits? I would get a remote tuner (like the SGC or LDG) if it would do better without radials than the current in shack LDG AT100Pro.
 
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#8
Your LDG tuner at the radio end should tune it to a usable match, but there will be a lot of loss in the balun and coax, that's just how that works. LDG tuners are not really meant for use right at a whip type antenna, they are more of a coax "line flattener". If you look at auto tuners designed for use on a whip or long wire the components are rated at much higher voltages than LDG uses because a random length wire or whip can have some wild impedance and very high voltage at the feedpoint.

Using your tuner at the radio end with the stock balun at the antenna and no radials makes a pretty grim antenna. It might make some contacts on the higher bands like 20 or 17m but not on 40 or 80. Put a bunch of radials or a couple of lengths of chicken wire under it and it will work much better. Put an SGC or similar wire/whip tuner on it with some radials and you won't recognize the antenna any more, it will impress you.

Does your RV have a metal skin? If so its commont to mount verticals to them and use the vehicle as the ground plane or counterpoise. You would still need an autotuner at the base of the antenna to make it sing.
prcguy

I have an Airstream trailer so I have a 30’x8’ aluminum roof with which to play. How to mount this up there is a different matter. Perhaps a mobile antenna of some sort. May need a different antenna? Better option than what I have?
 
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#9
A 27ft vertical with auto tuner at the base on a metal RV will beat any mobile mounted in the same place, even large screwdriver types. If you can find a way to mount the Zerofive like clamped to a ladder or ?? it could work very well.

I carry lots of antennas when camping in my small travel trailer and sometimes I use a 32ft Shakespeare military whip over lots of ground radials and a modified 500w Harris RF-382 auto tuner at the base. It works really well and I have to go with ground radials because my trailer is all fiberglass.
prcguy

I have an Airstream trailer so I have a 30’x8’ aluminum roof with which to play. How to mount this up there is a different matter. Perhaps a mobile antenna of some sort. May need a different antenna? Better option than what I have?
 
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#10
A 27ft vertical with auto tuner at the base on a metal RV will beat any mobile mounted in the same place, even large screwdriver types. If you can find a way to mount the Zerofive like clamped to a ladder or ?? it could work very well.

I carry lots of antennas when camping in my small travel trailer and sometimes I use a 32ft Shakespeare military whip over lots of ground radials and a modified 500w Harris RF-382 auto tuner at the base. It works really well and I have to go with ground radials because my trailer is all fiberglass.
prcguy
Thanks for the great effort to help!
Do not have a ladder. But could likely get a longer mast and somehow secure it to the frame or tongue. Could then mount the antenna so that the base would be above roof level. The roof would all be off one in one direction from the antenna but it might still work as a ground plane. ????
 
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#11
I think the most important thing to consider is where the auto tuner will mount. It would work best in the center of the roof and second choice might be centered lengthwise but on one side. Having it at roof level in a far corner is better than down on the bumper, etc. I all cases it should be well grounded with a short wide strap to the metal skin of the RV.

Just consider the Zerofive antenna as a stiff piece of wire. It can mount to a mast attached to the bumper with the wire connection point at roof level or higher and the tuner can be mounted high and grounded to the metal skin, then a short or even not so short wire can attach the hot of the tuner to the Zerofive. Any wire between the tuner and Zerofive becomes part of the antenna, no big deal for a non resonant HF antenna.

I got a fold over mast adapter for trailer hitches off Ebay. I use it ocasionally on my truck but I also had a trailer hitch receiver thingee made that is bolted to the top of my square tube bumper on my trailer. I can then use the fold over mast adapter on the bumper of my trailer with surplus military antenna masts up to about 25ft. You could do something similar to hold just enough mast to get the base of the Zerofive at roof level.
prcguy

Thanks for the great effort to help!
Do not have a ladder. But could likely get a longer mast and somehow secure it to the frame or tongue. Could then mount the antenna so that the base would be above roof level. The roof would all be off one in one direction from the antenna but it might still work as a ground plane. ????
 

W9BU

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#12
Perhaps I’ll spring for a remote tuner. Did you leave the unun in place?
Absolutely not. My AH-4 is mounted at the base of the antenna and connected to the antenna with a short piece of 14 gauge wire between the antenna terminal on the tuner and the radiating portion of the antenna. The radials connect to the ground terminal on the AH-4.
 

techman210

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#15
Some LDG tuners have a reputation to taking a long time to find that initial match- as long as 30-45 seconds. Once you have a match, that frequency is memorized in the tuner, and a return to that frequency will match almost instantaneously.

Your radio should be in AM to CW mode to provide the tuner a steady signal to get that I initial matching equation.
 
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#16
I too, K1JWJ-- think that your best bet is to go with a base mounted tuner- an auto tuner is good, but even a manual tuner is infinitely preferable to using that toroid transformer arrangement.
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All that aside, I will throw in a variable that is often overlooked with verticals- the resistive ground losses. You want to get the base of your antenna as high off the ground as practical- and keep the counterpoise up there as well. Ground losses are frequency dependent- the longer the wavelength, the higher the base needs to be. You can loose 3 dbs - half your power- alone to ground losses. That is in addition to the other losses- feedlines, loading coils---- that are working to decrease the radiated signal. The following formula does not address the efficiency of the counterpoise- it can be assumed for a mobile setup it will be 'lousy.' The antenna base height above ground is what important.
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Okay, want some math to go along with this? (probably not- but you ignore the physics at your peril...:) )
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The following is a Coyote formula for computing the efficiency of an HF mobile mounted 'whip' antenna.
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Terms used:
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h = height of the antenna in degrees (ie: a "quarter wave" is 90 deg.)
L = the length of the vertical in feet
E = Antenna Efficiency in %
Rg = Ground loss in Ohms*
Rc = radiation resistance of the loading coil **
Rr = h squared/312
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The "Formulas:"
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h = L/984 log (Frequency in Mhz) x 360
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plug this into ---
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E = Rr/(Rr+Rg+Rc(Cos squared x h)
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This will give the relative efficiency, in percentages-- of that vertical, - It will be dependent on frequency, ground losses, and loading circuit losses. (Notice that from the table below, it doesn't take much to raise Rg's Ohmic values- and hence drop the efficiency a lot)
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Maybe the math is a bit overwhelming- but anyone with the interest, and taking the time to work out some figures can see why a bumper mounted vertical stinks alongside the same antenna mounted high on the vehicle body. The big thing to take away from this is what that Rg figure does to the E %.
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Professionally I have used vehicle HF radios for many years- keeping my formula always in mind- Its nothing for one of our units to talk 800 miles daytime on 8 Mhz- 150 Watts SSB into a 6 foot base loaded vertical.
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..........................CF
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*Rg -- the ground losses, assuming the heigth of the base above ground... you can use 2 Ohms for ~4-5 feet, .... 10 Ohms for ~1-2 feet.... an obvious reason why the base needs to be elevated.

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Rc -- the Ohmic losses of a loading circuit. We'll assume this is a coil with an average Q of 300 Ohms, placed at the base of the vertical.
Rc for various Ham Band frequencies, assuming a whip length reasonable for a mobile station--
4 Mhz -- 6 Ohms
7 Mhz -- 3 Ohms
14 Mhz -- 1.4 Ohms
21 Mhz -- 0.5 Ohms
28 Mhz -- negligible
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#17
Ignore this- some how or another my stuff got posted twice.................. and I erased the second entry- almost
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So since I'm taking up space, I have this neat photo.............. :)
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#18
A friend glanced over what I wrote last night- my 'Editor' - and pointed out an error. I know better, but it slipped by me in the typing--
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The assume Rc Ohmic table is based on a Coil Q of 300, not "300 Ohms"..... what happens when you write something late at night... and in this case it is like Mark Twains observation-----
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": “The difference between the almost right word and the right word is really a large matter—it's the difference between the lightning bug and the lightning."
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............................CF
 
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#19
Extracted from W9RTB's Eham post:
I have about 16 radials from about 6’ to 25’ in length and two 5ft ground rods. I use a Balun Design UNUN and the LDG RT-100 tuner at the base of the antenna. The RT-100 tunes 10-40m wth no SWR higher than 1.2 to 1.
IMHO with no radials all you are doing is keeping the worms warm in winter.
 
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