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Author Topic: Carolina Windom antenna problem  (Read 2315 times)
N5MZL
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Posts: 38




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« on: April 25, 2004, 11:53:50 AM »

Sorry if this story is rather convoluted, but I'm in a bit of a quandary and any help would be appreciated.  

I am getting back into ham radio after a ten year absence, and HF operating has always been my favorite.  In the past I lived in a rural area, and could put up whatever sort of antennas I wanted, and was even pretty good at making my own dipoles for various bands.  

However, I now live in a subdivision that, while antennas are not forbidden outright, the civic association is vicious and not to be trifled with, hence I wanted to go with something at once stealthy but versatile.  

At first I thought to try the old stand-by, the G5RV, but in doing my Internet research on the issue, I came across this "Carolina Windom" multiband antenna, which seemed to give more bangs for the buck.  I ended up purchasing one from an outfit that will remain nameless here, to the tune of around $150, when you include shipping, rope and other incidentals.  

It was a bear of a job to put up, since I had to threat it through tree branches and whatnot (which is why I got the one with the insulated wire), but I got it up.  Suspended from trees, the "matching transformer" (looks like a balun to me) and the long segment of wire was up about 35', more or less horizontal.  The shorter end sloped down, with the end about 10' up (I had no alternative in this).  

After making up the 100 or so foot feed line (RG-8X) and grounding the rig (8' copper ground rod), I hooked up my Yaesu FT-890...and the SWR was through the roof on all bands.  

Anything more than a few watts, on 80 through 10m, made the radio shut down.  I checked continuity all the way back to the antenna, and everything seems OK, except the balun shows a dead short on my VOM.  However, the antenna maker says their balun is supposed to show a dead short, and when I took the antenna back down I could find nothing else wrong with it (no damaged insulation, all connections weatherproofed to the max, not that it had been up long enough to get wet, etc).  

Except for power and phone lines running along the back property line (and the slinky antenna I put up later is no further away from those than the Windom was, and I am having no problems with it), there was nothing metallic nearby to detune the antenna, and even if there was, I can't imagine even that would create the high SWR I am seeing.  

I called the manufacturer up and after telling me there was nothing wrong with the antenna based on what I told them, they just said to send the antenna back to them and they would "check it out".  

We finally get to my question.  I have been working on getting an antenna for weeks, and am tired of fooling with assorted vendors (have dealt with several during this process, and none have impressed me).  

Given how much I will pay out further on shipping the antenna both ways and the like, I am wondering if I would be better off simply buying a decent 4:1 balun, replace the existing "matching transformer" with it, and use the rest of the antenna components (wire, coax, RF choke), and if so, is this more likely to work?  Based on my research, the original Windom antenna design used a 4:1 balun, and the wire lengths of the antenna I bought look to be pretty close to specs per that design, which is why I suggest this option.

Unfortunately I am no antenna guru, and even with all the information I've found on the Windom, the data is a bit ambiguous on this point.  So, before I throw any more good money after bad, I would appreciate any help you all could give me in this matter.  Thanks and 73.
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N5KBP
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Posts: 287




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« Reply #1 on: April 25, 2004, 01:49:23 PM »

First I am no ant guru but I do have some experience with wire antennas.  My sugggestion would be to put up a dipole as long as you can fit even if you have to turn corners etc with it. Feed it with 450 ohm ladder line to as close as you can get to the operating position. Install a 4:1 balun at that point and feed it with some good RG-8 or 9913 from there to a tuner. If at all posibble run the ladder line all the way to the balun output on the tuner. The less coax the better. I have run this kind of setup for many years and it works well for me on all bands.  

Marty
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K1WW
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Posts: 51




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« Reply #2 on: April 25, 2004, 02:09:06 PM »

Unhook the coax and check it for a short or open.
Make sure you aren't shorted between the braid and center conductor.
What is the SWR reading?

73 Ray
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N5MZL
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Posts: 38




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« Reply #3 on: April 25, 2004, 02:45:15 PM »

I checked the coax first thing.  In fact, I checked both the coax I made up as well as the 20' section that came with the antenna several times, and they both checked out fine.  No shorts between shield and center conductor.  As for the SWR, I'm going by the meter in the radio, and it bounced around quite a bit, but the overall indication was well over 3:1.
The only short I found was in the balun, which the antenna maker said was supposed to be there.  

Bear in mind that the antenna tuner in this FT-890 is pretty stout for an internal.  I've had it on some pretty big mismatches over the years (like loading up on a 10m Ham Stick on 20 and 40; not very efficient, but it handled it), but never have I seen it behave the way it did on this Windom.  Anything more than 2 or 3 watts out, and it went clickety-click and shut right down, plus a "High SWR" indicator lit up that I didn't even know was on the radio.  
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KG6AMW
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Posts: 616




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« Reply #4 on: April 25, 2004, 02:45:35 PM »

I'll take a shot gun approach here. 1) I don't much about these antennas.  When I checked that famous antenna company that sells these, their ad says an antenna tuner is needed for all bands.  2) Running a wire through the trees might affect the swr to a point, more so if it rained recently. 3) Perhaps the vertical portion of the antenna is coupling with something nearby  4)  Running part of the antenna by large limbs may change the swr, but the question is by how much. Hope you can solve the problem. I'm interested to see what happens.  Good luck.

KG6AMW
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N5MZL
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Posts: 38




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« Reply #5 on: April 25, 2004, 03:01:05 PM »

Re KG6AMW

Yes, the say a tuner is needed for all bands, but according to a whole lot of people (including several on this site), the thing is generally resonant on the lowest band it's cut for, and a tuner is not always needed.  I know this is hearsay, and I always used the tuner in the radio.

AS for running the wire through the trees, this is why I got insulated wire, and it had not rained before or during the time I had the antenna up.  Also, there are all sorts of people out there using wire antennas strung through tree limbs, and as long as the wire is insulated in some way, even if the leaves and branches are wet, the SWR is not seriously affected.  At least I found a lot of people on the net who say they have done this, and had no significant SWR or performance problems, and even with this specific antenna.

The vertical element is (or was until I took the thing back down) hanging in the clear, and there is nothing nearby (except the tree trunk, which was 15' away) for it to couple to.

Thanks and 73
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W4TYU
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Posts: 518




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« Reply #6 on: April 25, 2004, 03:42:07 PM »

Hate to ask, but did you check the coax end to end to make sure that the center conductor is not open. It is not unknown for that to happen.
Ole man JEAN
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K3IXD
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Posts: 10




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« Reply #7 on: April 25, 2004, 03:58:35 PM »

Try substituting a dummy load for the antenna and see if the rig loads OK. I have seen two situations where the coax looks OK but with power applied the SWR shoots up. One was the result of water in hardline and the other was Pentetrox(tm) very near the terminals. Is there a ham near by who could do a temporary installation and see if the antenna played for him/her?
Good luck, Ed
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N5MZL
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Posts: 38




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« Reply #8 on: April 25, 2004, 04:03:04 PM »

Jean,

Right now I have the same coax connected to a "Cliff Dweller II" slinky antenna that I'd had stuck away in a closet for several years and never used until now.  The coax works fine on the slinky antenna.  I tested the 20' "vertical" coax and it's OK as well.

Thanks and 73
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AB0UK
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Posts: 74




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« Reply #9 on: April 25, 2004, 04:41:22 PM »

This sounds a bit familiar to me.  My Carolina Windom was up about five months and on a Christmas eve it suddenly developed very high SWR as you described.  Yep, the balun was the problem.  It took a couple of days of troubleshooting, as you did, to figure it out.  The maker of the antenna don't want to hear about it so many of the bits and pieces are in my junk box.

I replaced it with a half size G5RV and have been relatively satisfied with it for the year it has been up. I got it at wholesale is why I put it up.  Someone above described a dipole with ladderline.  That may be even a better way to go.  In antennas simplier is usually better.

Good luck and 73,

Jim, AB0UK

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KC8VWM
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Posts: 3124




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« Reply #10 on: April 26, 2004, 12:15:47 AM »


>> I am wondering if I would be better off simply buying a decent 4:1 balun, replace the existing "matching transformer" with it <<

Baluns can in many cases be the problem. They will often exhibit a closed circuit when checked with a VOM even sometimes if they are functioning properly or not. This can sometimes be apparent with defective baluns even though they arrive new in the package.

Also ensure that you are using the correct balun for your particular antenna configuration. I prefer to use 4:1 baluns with coaxial cable. Look for the ones that offer a built in gasfet type lightning arrestor.

Since you are not revealing the antenna source or brand name, I will assume your antenna is designed to operate from 10 - 80 meters. I will refer to it as the "Carolina Windom 80"

If the "Carolina Windom 80" antenna you ordered may be intended to be used with 300 ohm feedline instead of the current 50 ohm RG8X feedline as you described.

This would usually require that you change your feedline to the manufacturers recommendations or possibly use a different balun than the one supplied with your order from the manufacturer.

It is also noteworthy to indicate that some antenna's dimensions require that the feed line's length is tuned specific to the length of the wire antenna.

A Carolina Windom 80 antenna fed with RG8X appears in an article with supplied link below. The dimensions in this article may differ from that Carolina Windom 80 antenna dimensions that you describe in your configuration. This is when fed with RG8X feedline as opposed to ladderline.

http://www.gw3vvc.freeserve.co.uk/carolina.htm

The article indicated the following:

>>> The Carolina Windom is basically a co-ax fed OFCD antenna but has a fixed length of coaxial cable forming an integral part of the antenna. <<<

The article clearly indicates that when using a "fixed" length of RG8X feedline, it becomes part of the antenna.

the dimensions described in the article for the Carolina Windom 80 are as follows:

>>> The antenna consists of the dipole itself, total length 66 feet, with a balun placed 41 feet from one end.  This balun has a 10 foot length of coaxial cable trailing from the bottom and terminating in a choke. This cable is the vertical 'radiator'. <<<

>>> Jim recommends using RG8X for the feeder because of it's low loss and cheap availability.  He also recommends a feeder length of 86 feet for the Carolina Windom 80 Special.  This should ideally present an 'acceptable' swr on all bands 80 to 10. <<<

The use of RG8X coax on the antenna as described in the article indicates that the "feeder" length should be 86 feet otherwise the antenna may not resonate properly.

However, if your Carolina Windom 80 antenna was originally designed to be used with ladderline as opposed to RG8X, then the antenna's overall dimensions, including the feeder line will usually differ significantly.

73

Charles - KC8VWM
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N6AJR
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« Reply #11 on: April 26, 2004, 03:52:53 AM »

Fan Dipole
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KB8MOU
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Posts: 2




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« Reply #12 on: April 26, 2004, 09:03:26 AM »

I have used a famous brand carolina windom for 7 plus yrs without any problems.  The center balun is a 4:1 balun and does test as a short between all elements. This is normal with a VOM.  I assume you have checked the line isolator at the end of the vertical segment for continuity. This is a simple choke balun with coax wrapped around the ferrite rod. I have used mine hanging in the trees without a problem. Almost certainly the balun at the center is the problem. Try a different 4:1 balun as the easy test solution.

Paul
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K0IZ
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« Reply #13 on: April 26, 2004, 12:36:08 PM »

In the ARRL "More Wire Antenna Classics, Vol 2", there is a reprint of off-center fed dipole from QST Aug 1990.  The article shows SWR's for various bands with 4:1 and 6:1 baluns.  4:1 provided "somewhat sharper resonances and lower SWR on 80/40 but low SWR not obtainable on 20m.  6:1 was better compromise.

Based on using the existing coax same connectors) with slinky, it would seem the coax is ok.  Connecting a dummy load to the coax and checking SWR would confirm this.

Assuming you still have your balun and can disconnect from the antenna, put a 200 ohm resistor (1 or 2W carbon) across the antenna terminals of the balun.  If the balun is working correctly, the 200 ohms should be seen by the rig (use very low power!) as 50 ohms (or close).  If still high SWR, the balun is bad, no matter what they say.

I have made many baluns, and the above resistor test always works.
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W9OY
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« Reply #14 on: April 26, 2004, 04:12:55 PM »

If you get frustrated I would just yank the balun, go to radio shack and get 100 feet of 300 ohm twinlead, cut it to about 84 feet put one end at the same spot in the antenna where the balun previously was connected and run the twin lead through the wall to a tuner, using a 1:1 current balun.  This will maintain your stealth, give you good efficiency, and get you on all bands.  Use a current balun and not a voltage balun.  Most 4:1 baluns are voltage baluns.  If the length of your coax between your rig and the outside wall is short, (under 15 feet or so) you can just leave the balun outside and use the coax to get you to the rig. Unless your tuner in the rig has a wide range you will probably need a manual tuner to get the job done.  I presently am using an ameritron art-15 tuner, and a DX engineering balun at 1500W on this type of antenna.  For low power a good tuner would be the old Johnson matchbox 275W version.  Usually about $100 or so on ebay.  If you get the Johnson, you won't need a balun since it is inherently a balanced tuner.  The Johnson tuner is good to about 700W on CW more on SSB but not the leagal limit.  I have this setup on a second antenna.  One disadvantage of the Johnson is that it does not cover 160 and some of the WARC bands are spotty.  I figured out a simple mod for the matchbox that improves its coverage, but that is the subject of another conversation.        

The balun I use presently is from DX engineering, and I am very happy with its design.  I think it is basically indestructable at anythig that is legal power.  Pay a little more and get a good balun.  I ground the balun with a ground rod and a short wire before the coax enters the house.  

84 feet is 3/8 wavelength on 80M for the velocity factor of this feedline.  A common rule of thumb for feedline length is to use an odd eigth wavelength eg 1/8, 3/8, 5/8 etc. on the lowest frequency to be tuned.  If yours is not an 80M antenna then recalculate for the freq that is the lowest using (L=Vf*551/mhz) where Vf= the vel factor of your feedline (0.8 for the Radio Shack line), mhz= the freq of the lowest band operated in mhz, and L= the length of 1/8 wavelength in feet, at that freq for that type of feedline.

This may sound like more goofing around than you want to do, but presumably you will be at this qth for a long time, and you might as well get a good antenna system going in the first place.  The parts of this a.k.a. the tuner, balun, and twinlead can be used to feed many types of antennas so you will only have to make the purchase of these items once.  I have 2 antennas using this setup, one off center fed like your antenna, and the other center fed and I am happy with the performance of both.  I changed to this setup from a Carolina windom and also from a Superloop by the same company, and I like the performance of these antennas I am using better than the radio works antennas.  I did A/B comparisons between these and the radio works antennas at similiar heights and these work better.

Hope this is of some help to you.
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