5/8wave workman swr issues? Balun? Unun?

[ghutch]

Bought a workman 5/8 wave- maco copy to use on an island Dx trip. Took it to the beach, (80 ft from the surf), set it up per the instructions. Placed it on a 12 foot metal mast, rope was used as guys,coax was tied to the mast straight down to the sand, remaining coax(70 ft) was loosely coiled laying on the sand and run 20 ft to the radio. Mast on this antenna is bolted direct to the base of the antenna.
Adjusted the matching coil or ring around the base as instructed to the tap point. The instruction say at the point were swr is appro. the same on both ends of the ban (done)....final swr adjustment is done by shortening the radiator1/4 inch at a time until the match is down. Did it all by the book. Issue is to get down to 1.75 swr I had to shorten the radiator 2.5 feet. .? much shorter than the listed 27mhz length in the instruction packet? Any ideas?? Help?
The radial spider is 1/2 inch below coax connector per instructions
4 Radials are at 102inches ,mast was set 6-8 inches in damp sand, no ground rod was used,
I do not know where to start? No balun or coil was built or coils of coax made at the base as I do not know the needed specs etc to turn one? Could this be the issue? I know this antenna should get below 1.5-7 and the overall is 20 inches shorter the the 240 inches shown? After reading about common mode currents and coax radiating Im at a loss .... Could the saltwater being very close cause these issues...I would think it would be helpful ? Does anyone know of a modeled antenna such as this one? Homer have you any ideas? Marconi?
Any help or ideas

 

[HomerBB]

Off the top of my head unless I could physically examine the antenna it is not easy to say.
Take a look at this thread http://www.worldwidedx.com/cb-antennas/118216-maco-5-8-high-swr-when-rains.html

As for the choke, it won't fix what is likely a mechanical problem with either your antenna, or your coax.
To make the choke, simply wrap five wraps of your coax close to the antenna feed point side-by-side about 4-1/4" diameter. Done.

 

[The DB]

Adjusted the matching coil or ring around the base as instructed to the tap point. The instruction say at the point were swr is appro. the same on both ends of the ban (done)....final swr adjustment is done by shortening the radiator1/4 inch at a time until the match is down. Did it all by the book. Issue is to get down to 1.75 swr I had to shorten the radiator 2.5 feet. .? much shorter than the listed 27mhz length in the instruction packet? Any ideas?? Help?

The Maco version of the directions has you adjust the antenna by either the tap point on the ring or the length of the antenna. You don't have to adjust both. I am not familiar with the Workman version of the directions, but shortening it by 2.5 feet is a bit extreme. That would take the length from 11 meters and put it down below the 10 meter band.

I generally tune these antennas with an analyzer and have never had to adjust the length of the antenna from the Maco version of the instructions.

I assume you don't have access to an analyzer, so what I would do it put the length back on where the directions claimed they should be, and simply use the tap point on the ring. If you are still having trouble after that try putting the SWR meter right at the feed point of the antenna for measurements. If you don't have a perfect SWR match the coax will throw off the SWR readings unless you are at a perfect half wave multiple (accounting for the coax velocity factor) down the coax. Even at those points it can still throw off the readings some. It is possible that it is either showing as higher or lower than it actually is due to the effects of the mismatch at the antenna itself.

An unun could help, however, to make one you need to know the impedance of the antenna itself. You could also use an antenna tuner at the feed point of the antenna (or even elsewhere on the coax) to match your SWR if worse comes to worse.

I do not know where to start? No balun or coil was built or coils of coax made at the base as I do not know the needed specs etc to turn one? Could this be the issue? I know this antenna should get below 1.5-7 and the overall is 20 inches shorter the the 240 inches shown? After reading about common mode currents and coax radiating Im at a loss .... Could the saltwater being very close cause these issues...I would think it would be helpful ? Does anyone know of a modeled antenna such as this one? Homer have you any ideas? Marconi?
Any help or ideas

An air choke (it is not actually a balun, even an ugly one, despite the common name for it) will not have any significant effect on SWR, if any at all. That being said, with the extra coax you said you have laying around it won't hurt anything in your case either.

The saltwater shouldn't hurt anything either. It has the potential to affect the tuning of the antenna as it is about as near a perfect ground as you can get on the planet and no other earth ground comes close, however, tuning adjustments for it should easily be within the range of the antenna if it needs any adjustment at all.


The DB

 

[BOOTY MONSTER]

was the radio in a mobile ? if so you might be getting reflection from the vehicle being so close . were there any buildings or sheds near by ?

 

[Marconi]

Off the top of my head unless I could physically examine the antenna it is not easy to say.
Take a look at this thread http://www.worldwidedx.com/cb-antennas/118216-maco-5-8-high-swr-when-rains.html

As for the choke, it won't fix what is likely a mechanical problem with either your antenna, or your coax.
To make the choke, simply wrap five wraps of your coax close to the antenna feed point side-by-side about 4-1/4" diameter. Done.

With this antenna, I agree with Homer, the instructions can be a bit confusing, whether due to misprints or confusion about where to measure the overall length. I also agree with some of the points that The DB raises.

I also agree that the choke will not fix mechanical problems or dimension errors, but if you use one...try as best you can to get the choke as close as possible to the feed point itself. In the theory of chokes, close is best. The location of the radial hub, and the space between the coil ends can also be important.

Below is an example of how close to the feed point a choke needs to be. The short coaxial pig tails shown in the middle of this image has a ferret choke right where the two pig tail wires start and end. This is the feed point for this Moxon antenna.



Regarding sandy beaches and the ocean mounting idea you mention. It has been my experience that sandy beaches do not always relate as though you were over ocean water. You will likely find better performance over salt water marshy land where there is plenty of Mother Earth's terrafirma.

 

[ghutch]

I built the antenna per the instruction...even went to the maco site to see if the china instructions had any change....none they are the same.
Yes booty I thought the same thing about the auto it was about 20 feet away? But it as the only thing near it Other than 3 metal ground stakes driven in for the guy ropes, could be be part of the issue...but I don't think it is all?
I don't know hoe to measure the impedance of the antenna ??
DB....Reading sites tells me I want a 50 ohm antenna so all power is radiated but I do not know how to measure this? Also site are telling me vertical 5/8 have common mode issues so thoughts on a coil/ choke. I used the ring at first to lower the swr...it stated in the instructions to start at 6 inches...assembled the tubing per the instruction and the swr went 3-4. I adjusted the length at the first connection above the base. Got down some but not near where it should be...finally moved it almost to the next connection and ended up at 1.5
I have looked at some sites with models that show the coax and the mast
coupled to the antenna and radiating....they claim these gp verticals are not a good match and have issues with everything becoming part of the radiator?
Is 10 feet high enough to get a good starting measurement ? I could go higher but with the antenna layer over making adjustment back to vertical did not make but slight changes.
If an antenna matches is used it only fools the radio for matching...but has loss of signal or radiated power? Correct? Bth on rec and transmit?

 

[ghutch]

Marconi...the beads or rings are to kill any stray rf on the coax shield ? CM current ...they are placed at the feed point or as close us possible...but reading a couple website only confuses me more....size the makeup are critical...used wrong they can make matters worse. I looked for some of your models thinking it. Might tell me something but all models I found showing gp antennas were at various tall heights....my antenna must max out at 20 feet...next to saltwater...in fact the mast will be in saltwater at high tide. This install is in the Land Cut south of corpus just north of port Mansfield it should be almost perfect ground....?

 

[HomerBB]

ghutch
Your antenna at that height over that ground will tune just fine.
Double check the integrity of the coax and that there are no shorts on the antenna where it is assembled between the ring and the center conductor strap except for where it is tapped to the ring.

 

[ghutch]

Homer...I process right now of re checking connections and all measurement per the instructions.
Question about using a alum to alum anti corrosion compound at these tubing joints? Has anyone used this stuff? Is it needed?
Without antenna analyzer is there a way to ck he ohms at the antenna?

 

[HomerBB]

I don't use the anti-corrosion compounds because I never leave my antennas together long enough to matter.

Without trying to sound contradictory to anything said before, it isn't necessary to be aware of the impedance at the feed point of your antenna in order to get the SWR right. The manufacturer has done all that for you, and if the antenna is in good mechanical shape, not grounded where is shouldn't be, or nothing not connected as it should be, and your feed line in good shape ( a simple multi-meter will tell you whether there is conductivity from one end to the other, or if there is an unwanted connection between the braid and the center conductor) then you should be able to achieve a proper SWR. When you have a 1.0:1 SWR the antenna and the feed line are at the same 50 Ohms impedance. If it reads 2.1:1 then the antenna (load) will be about 100 Ohms versus the coax being about 50 Ohms.

Anyone I have communicated with about your problem has usually had to look in the area of where the tapping strap connects to the top of the feed point.

 

[Marconi]

Homer...I process right now of re checking connections and all measurement per the instructions.
Question about using a alum to alum anti corrosion compound at these tubing joints? Has anyone used this stuff? Is it needed?
Without antenna analyzer is there a way to ck he ohms at the antenna?

ghutch, my point was concerned about being on a sandy beach. This is where I have seen null type performance compared to being on brackesh productive land near the sea.

You might need to compare instructions. Some of the newer manuals have been produced (not the old Maco's) have been reported to have some dimensional errors. I have some manuals to compare if you need them.

There is a product on the market at www.AESham.com that sells a non-conductive teflon feed point product called "Stuf" that goes inside of the PL259 connector, and it helps prevent water from entering the feed line, and the Workman antenna design may well benefit from the use of such a product.

I use Pentrox (same company) to help relieve freezing of aluminum joints with antennas for use over time. Of course make sure the tubing is clean and the joint end as nice an smooth, and then use a little dab of Pentrox a conductive gel.

It is also a good idea to replace your nuts and bolts with stainless.

 

[Marconi]

I don't use the anti-corrosion compounds because I never leave my antennas together long enough to matter.

Without trying to sound contradictory to anything said before, it isn't necessary to be aware of the impedance at the feed point of your antenna in order to get the SWR right. The manufacturer has done all that for you, and if the antenna is in good mechanical shape, not grounded where is shouldn't be, or nothing not connected as it should be, and your feed line in good shape ( a simple multi-meter will tell you whether there is conductivity from one end to the other, or if there is an unwanted connection between the braid and the center conductor) then you should be able to achieve a proper SWR. When you have a 1.0:1 SWR the antenna and the feed line are at the same 50 Ohms impedance. If it reads 2.1:1 then the antenna (load) will be about 100 Ohms versus the coax being about 50 Ohms.

Anyone I have communicated with about your problem has usually had to look in the area of where the tapping strap connects to the top of the feed point.

Homer, I don't know if it makes a difference, but two of my manuals, that happen to show an 8" difference in the overall length detail, both show the coil turns in a counter clockwise rotation. This image above shows the opposite, clockwise rotation. Personally, I don't think it should make a difference.

One instruction shows the feed point bracket with the L shape part pointing up, and the other shows this part pointing down.

I believe the SO239 feed point connector can be removed from the bracket, so it can easily go on either side, and this probably makes little difference with how it works, but it is still a difference.

Just to show there are differences.

 

[The DB]

I don't know hoe to measure the impedance of the antenna ??
DB....Reading sites tells me I want a 50 ohm antenna so all power is radiated but I do not know how to measure this? Also site are telling me vertical 5/8 have common mode issues so thoughts on a coil/ choke. I used the ring at first to lower the swr...it stated in the instructions to start at 6 inches...assembled the tubing per the instruction and the swr went 3-4. I adjusted the length at the first connection above the base. Got down some but not near where it should be...finally moved it almost to the next connection and ended up at 1.5

a 1-1 SWR will put the antenna at 50 ohms of impedance. a 2-1 SWR will put the antenna at either 25 or 100 ohms of impedance. A 2-1 SWR reading at the antenna will reflect 11% of the power back instead of transmitting it. Sounds big at first glance doesn't it? to put it into perspective, it is just over 1/40'th of an s-unit. In reality, very few people on the receiving end will notice anything less than a 1/2 s-unit change. I know people push for that perfect SWR reading, but once you get past a certain point there really isn't much of a difference, unless you are setting up a resonant antenna, at which point the resonant point will be the best point to tune the antenna to. Unfortunately you need an analyzer to do that, and from someone who has done that a time or 100 in the past the resonant point is very rarely at 1-1 SWR (or the 50 ohm impedance point).

Also when it comes to SWR, unless it is one of a few specific lengths, your coax will have an effect throwing off the reading. Down at the far end of the coax where your SWR meter is may not be actual SWR of the antenna. The actual SWR of the antenna may be better or worse than what is being shown. The only way around this is to put the SWR meter at the feed point of the antenna.

Is 10 feet high enough to get a good starting measurement ? I could go higher but with the antenna layer over making adjustment back to vertical did not make but slight changes.
If an antenna matches is used it only fools the radio for matching...but has loss of signal or radiated power? Correct? Bth on rec and transmit?

10 feet is a good height for tuning. I usually tune these antennas on a 10 foot mast zip-tied to a fence post before mounting them up high. The SWR does change some when putting it up high but not usually much (generally in the range of .2 or .3 SWR, and sometimes for the better).

Antenna tuners, when used properly, do more than just fool the radio. The ring on your antenna is in itself a specifically designed antenna tuner. A tuner used at the feed point of an antenna becomes a matching network for the antenna. Most antennas have some form of matching network (or tuning network) built into their design. Yes you will loose a miniscule amount of power, but then you will loose some power simply because there is coax between the radio and antenna.


The DB

 

[Marconi]

ghutch, here is a instruction sheet that was reportedly produced by the premiere installer of antennas, world wide, and beyond, Master Chief and he tells us so in the first sentence.

View attachment Master Chief's Instruction on the V58.pdf

 

[HomerBB]

Homer, I don't know if it makes a difference, but two of my manuals, that happen to show an 8" difference in the overall length detail, both show the coil turns in a counter clockwise rotation. This image above shows the opposite, clockwise rotation. Personally, I don't think it should make a difference.

One instruction shows the feed point bracket with the L shape part pointing up, and the other shows this part pointing down.

I believe the SO239 feed point connector can be removed from the bracket, so it can easily go on either side, and this probably makes little difference with how it works, but it is still a difference.

Just to show there are differences.

You are correct, those differences are incidental to the entire physical makeup and of no consequence. The point is be sure there is isolation where it should be, and conductivity where it ought to be.

Also, DB's advice is very good.

You may be straining at a gnat, here.