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Post by homerbb on May 16, 2012 8:49:16 GMT -5
A 27' tall + 20' mast height Sigma 4 would certainly have given you the bet performance. On the other hand, the S4/V4k design rocks down low compared to other antennas. Even with my homebrew the V4k was way ahead of other antennas down low. The AP does well there, too, but it is just great higher up.
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Post by cbrown on May 16, 2012 8:50:30 GMT -5
Ya, both the Astroplane and the Astrobeam liked being a high as you could mount them. A lot of people here had them, and they worked well.
After a few early antennas, I used an Avanti Sigma II (AV-170). Worked really well for me. Nowadays I'm happy with the Interceptor I-10K.
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Sandbagger
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Post by Sandbagger on May 17, 2012 6:29:57 GMT -5
Ya, both the Astroplane and the Astrobeam liked being a high as you could mount them. A lot of people here had them, and they worked well. After a few early antennas, I used an Avanti Sigma II (AV-170). Worked really well for me. Nowadays I'm happy with the Interceptor I-10K. I had an AstroBeam back in the 80's and I loved that antenna. It had decent forward gain, but what I liked most about it was the fantastic F/B ratio. I could literally take the signal of the guy 7 doors down the street from me from over +30db down to +10db, and guys a mile away could get over him. I actually got a better signal from my neighbor when I unscrewed the cable from the back of the radio, when the beam was pointed away. By the time I got that antenna, I had put up a 40' tower so my height also improved a bit as well.
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Post by cbrown on May 17, 2012 8:37:19 GMT -5
Avanti made some nice antennas. I even had a Moonraker 6 up back then.
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Post by homerbb on May 23, 2012 12:09:01 GMT -5
I am going to be away from the house at my in-laws in about 3 week for a week and will need a portable antenna. I have a dipole for that purpose, but decided to throw together a portable end fed wire, too.
The wire element is wrapped around the plastic plate for travel/storage.
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Post by homerbb on May 23, 2012 17:53:09 GMT -5
If interested, how to make the coil in the above photo. Materials: wire wax paper blue swimming pool flex hose Hot glue. 1. Cut a section of this hose, cut it into strips. 2. Wax paper rolled and taped onto cylinder such as PVC pipe. 3. Hot glue strips of hose onto wax paper. 4. Wrap wire for coil around the form into the grooves. 5. Hot glue across all the blue hose strips. 6. Slide wax paper off of the PVC form, remove wax paper from within the coil.
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Post by cbrown on May 24, 2012 8:36:00 GMT -5
Very ingenious!
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Post by cbrown on May 25, 2012 8:39:57 GMT -5
Also, I'd tin those jumper wires. I just hate to see un-tinned wires in connections.
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Post by homerbb on May 25, 2012 18:30:54 GMT -5
Just a little funny. I hear ya
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Post by homerbb on Jun 3, 2012 20:39:17 GMT -5
It grew a set of groundplanes:
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Post by homerbb on Jun 4, 2012 22:01:20 GMT -5
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Sandbagger
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Post by Sandbagger on Jun 5, 2012 6:50:12 GMT -5
While down on the ground the EFHW went through a couple of modifications. 1. It grew a set of 3' x 12 GP radials. 2. It was also outfitted with a slightly smaller matching network. Are 3' radials really that effective? I would think they'd need to be at least 1/8th wave to actually do something, preferrably 1/4 wave optimally for a decent artificial ground plane.
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Post by homerbb on Jun 5, 2012 10:51:51 GMT -5
While down on the ground the EFHW went through a couple of modifications. 1. It grew a set of 3' x 12 GP radials. 2. It was also outfitted with a slightly smaller matching network. Are 3' radials really that effective? I would think they'd need to be at least 1/8th wave to actually do something, preferrably 1/4 wave optimally for a decent artificial ground plane. Sandbagger. I am with you, however there is that very question among others I am trying to answer. Companies like Sirio regularly use such short radials but more than the usual four with apparent success. I tried this same set of radials on a 5/8 wave and discovered it to be inferior to a 4 x 9' set of radials here. The question for me is whether a 1/2 wave will profit on the air with radials, and whether the performance of this 3' x 12 set have a different effect on the 1/2 wave than they did on my 5/8. So far the antenna seems to be highly effective with them. I will remove them and retune as necessary to offset the removal of the radials and run without them for a sense of things. I am not the technical wizard many of you are, but more of an empiricist, weighing my experience against a technical argument any day. It may hold that they are useless at that length, but I'll see. BTW. at 3' x 12 radials I have the same physical mass as 9' x 4 radials. Yes., I know it is electrical not simply physical aspects that matter, but it is a mere test . . .
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Post by homerbb on Jun 5, 2012 15:27:01 GMT -5
For the record here is a list of the analyzer readings in the shack using about 84' of RG8/u coax:
2.0 ------------------- 29.288 ---- R27 --- X5 2.0 ------------------- 29.160 ---- R28 --- X9 1.5 ------------------- 28.485 ---- R55 --- X23 1.4 ------------------- 28.210 ---- R71 --- X0 1.0 ------------------- 27.523 ---- R70 --- X0 1.0 ------------------- 27.405 ---- R60 --- X0 1.0 ------------------- 27.089 ---- R60 --- X0 1.1 ------------------- 27.062 ---- R58 --- X0 1.5 ------------------- 26.283 ---- R98 --- X0 2.0 ------------------- 25.507 ---- R120 -- X0 2.0 ------------------- 25.401 ---- R101 -- X7
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Sandbagger
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Post by Sandbagger on Jun 5, 2012 16:50:44 GMT -5
Are 3' radials really that effective? I would think they'd need to be at least 1/8th wave to actually do something, preferrably 1/4 wave optimally for a decent artificial ground plane. Sandbagger. I am with you, however there is that very question among others I am trying to answer. Companies like Sirio regularly use such short radials but more than the usual four with apparent success. I tried this same set of radials on a 5/8 wave and discovered it to be inferior to a 4 x 9' set of radials here. The question for me is whether a 1/2 wave will profit on the air with radials, and whether the performance of this 3' x 12 set have a different effect on the 1/2 wave than they did on my 5/8. So far the antenna seems to be highly effective with them. I will remove them and retune as necessary to offset the removal of the radials and run without them for a sense of things. I am not the technical wizard many of you are, but more of an empiricist, weighing my experience against a technical argument any day. It may hold that they are useless at that length, but I'll see. BTW. at 3' x 12 radials I have the same physical mass as 9' x 4 radials. Yes., I know it is electrical not simply physical aspects that matter, but it is a mere test . . . If I could have a nickel for everytime standard theories had to be tweaked in order to work right, or something that shouldn't work well accroding to conventional wisdom but does, I'd be rich. So in that vein, I'm with you. It's a heck of a lot more fun to actually experiment and log the results, than to fall back on dogmatic theory without question. I'm sure the enginers at Avanti were doing it on company time, with unconventional designs like the Astro Plane and the Sigma 4. Standard theory has stated that any more radials than 4 (and they should be 1/4 wave) will not improve counterpoise performance. There have been antennas in the past (both near and distant) that have tried adding more (Sirio, and the Super Starburst come to mind) radials, and those are typically 1/8th wavein length. Don't know if the added radials really added any additional gain or changed the angle of radiation enough to show improvements, or whether it was simply clever marketing. The Starburst antennas were offered as a standard "Starburst" with 5 1/8th wave radials, while the "super" version added a second staggered level of 5 additional for a total of 10. Locals around here backin the 70's who ran them all swore by them, but no one ever to my knowlege ever A-B'ed them with another design to see signal differences. If I had more time, I'd love to set up an antenna range and do those checks with a field strength meter and more distant receivers (which I could access remotely via the internet), to see those minute differences.......
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Post by cbrown on Jun 6, 2012 9:11:58 GMT -5
The question for me is whether a 1/2 wave will profit on the air with radials, and whether the performance of this 3' x 12 set have a different effect on the 1/2 wave than they did on my 5/8. It might help change the antenna radiation pattern.
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Post by homerbb on Jun 6, 2012 10:53:27 GMT -5
I am closed in by houses here, and no one interested enough in what I'm doing to help me run any field strength tests on it, so all I have is to monitor performance to some known stations and see if I can detect differences.
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Post by cbrown on Jun 7, 2012 9:15:24 GMT -5
I am closed in by houses here, and no one interested enough in what I'm doing to help me run any field strength tests on it, so all I have is to monitor performance to some known stations and see if I can detect differences. Ya, I know what you mean. Besides, using a field strength meter brings in a lot of variables, including body position and height that you are holding the meter. I always wanted to set a few up around the perimeter of the property and have small video cameras on the meters to see the readings.
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Post by Sandbagger on Jun 7, 2012 10:04:38 GMT -5
I am closed in by houses here, and no one interested enough in what I'm doing to help me run any field strength tests on it, so all I have is to monitor performance to some known stations and see if I can detect differences. Ya, I know what you mean. Besides, using a field strength meter brings in a lot of variables, including body position and height that you are holding the meter. I always wanted to set a few up around the perimeter of the property and have small video cameras on the meters to see the readings. Yea, you can't make accurate measurements when your body is in the field of measure. You pretty much have to run remote antennas connected to the FS meter via shielded feedline. When we do FCC part 15 tests, the antenna is operated remotely via a small motor which can raise or lower the antenna height and the antenna polarity can also be rotated to cover both E plane and H plane patterns. I was fascinated by range measurements ever since I was a kid when our Explorer post had a guy come in to demo antenna measurements using UHF frequencies, so that antenna sizes could be kept small. We plotted the pattern of a dipole and 3 element beam on paper, based on the readings we got from the meter. Nowadays we have analyzers that can do that directly, but it's still interesting.
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Post by homerbb on Jun 7, 2012 20:07:36 GMT -5
I have to be honest about the antennas I tinker with. I love just making them and seeing whether I can make them work. The whole analyzer piece I've been doing lately has provided more challenges to getting the things just right than is sometimes as comfortable and laid back as I prefer. The hardest part of it is being forced to look at things I wasn't seeing before. I have to try to determine if what I'm getting from the instrument readings are losses, or whether it is resonant where I want it despite SWR readings, or how to control . . . have mercy at the pressure to learn what before was so simple - SWR bandwidth. . . So, in spite of the fun the field strength tests would be if I had the right setup for it, I'm already worn out. ;D Oh to be young again.
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Post by homerbb on Jun 7, 2012 20:12:11 GMT -5
Are 3' radials really that effective? I would think they'd need to be at least 1/8th wave to actually do something, preferrably 1/4 wave optimally for a decent artificial ground plane. I think I'll try couple things more before I move on to something else. I will disconnect the radials from ground of the match section and see what happens, I will take four to six of the 3' radials off and replace them with 4.5 ' - 5' radials, and I will remove the radials completely and see where things land since I readjusted the length and replaced the matching section. I fear you have raised a reasonable point here.
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Sandbagger
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Post by Sandbagger on Jun 8, 2012 6:47:13 GMT -5
Are 3' radials really that effective? I would think they'd need to be at least 1/8th wave to actually do something, preferrably 1/4 wave optimally for a decent artificial ground plane. I think I'll try couple things more before I move on to something else. I will disconnect the radials from ground of the match section and see what happens, I will take four to six of the 3' radials off and replace them with 4.5 ' - 5' radials, and I will remove the radials completely and see where things land since I readjusted the length and replaced the matching section. I fear you have raised a reasonable point here. Well, I have faith that you will come up with answers. I admire your tenacity to perform these experiments. I just wish I had the time to play in that sandbox. I'll just have to live vicariously through your projects. Keep them coming!
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Post by cbrown on Jun 8, 2012 9:25:08 GMT -5
Well, I have faith that you will come up with answers. I admire your tenacity to perform these experiments. I just wish I had the time to play in that sandbox. I'll just have to live vicariously through your projects. Keep them coming! Same here, Homer! I'm enjoying the metal exercise. Keep with it.
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Post by homerbb on Jun 8, 2012 14:20:27 GMT -5
I'm headed into the back yard in a few minutes to replace a half dozen of those too-short radials with some that are 59" long. I know 9' radials would do it, but I am just wanting to settle a question regarding whether, and how, radials affect an end fed 1/2 wave antenna in a noticeable way. BRB.
And thnx for the vote of confidence. Good thing I'm not driving the bus!
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Post by homerbb on Jun 8, 2012 21:46:38 GMT -5
As I had told some I was to do, I once again went back to the anttenna. I had suspicions regarding the way things were going with the MFJ-259b redings. I did several things in order to be sure of my controls on this antenna. 1. I took a continuity tester and sampled different ones of the radials. What I found was that some were not well connected in the system. I had a fix. 2. I replaced 6 of the 12 three feet long radials with 6 fifty-nine inch radials. Common wisdom states that the radials need to be at least 1/8 wavelength to be effective. I now had 6 x 3' and 6 x 5' radials for my GP. To cure the issue with some of the radials not having good ground to the system I ran an additional wire around the entire thing and checked continuity. All of them were now firmly in the system. 3. I now attached my analyzer directly to the feedpoint using two female threaded couplers and a single double male threaded coupler. This gave me the reach through the GP to the SO-239 on the antenna. This was done standing on the tuning platform of my tower with the antenna feedpoint at 21' height above the ground. 4. I then went into the shack and took a series of analyzer readings through the feedline at antenna FP height 21' 5. Lastly, I raised the antenna FP to 37' and took another series of analyzer readings from the shack end of the feedline. Results below. I measured the bandwidth as the matching network had been set before modifications to the radials at 21' height:
SWR ---------- Freq ------ X ---- 0
2.0 --------- 28.766 ---- 55 ---- 18 1.5 --------- 28.358 ---- 49 ---- 23 1.1 --------- 27.549 ---- 57 ---- 1 1.2 --------- 27.405 ---- 59 ---- 5 1.3 --------- 27.185 ---- 64 ---- 11 1.5 --------- 26.951 ---- 68 ---- 19 2.0 --------- 26.455 ---- 85 ---- 17
Moved the tap point on the coil to try to center on 27.400
2.0 --------- 28.449 ---- 65 ---- 18 1.5 --------- 28.035 ---- 48 ---- 22 1.0 --------- 27.395 ---- 59 ---- 0 1.1 --------- 27.185 ---- 63 ---- 0 1.5 --------- 26.727 ---- 73 ---- 14 2.0 --------- 26.324 ---- 85 ---- 22
I had the center where I wanted it, but I didn't want to have the bandwidth so low, so I adjusted the variable aluminum flat bar capacitor.
2.0 --------- 28.907 ---- 55 ---- 18 1.5 --------- 28.444 ---- 48 ---- 22 1.2 --------- 28.027 ---- 49 ---- 9 1.3 --------- 27.406 ---- 60 ---- 10 1.5 --------- 27.086 ---- 67 ---- 20 2.0 --------- 26.554 ---- 86 ---- 17
Results from the feedline in the Shack at 21' height.
2.0 --------- 29.552 ---- 25 ---- 4 1.5 --------- 28.652 ---- 52 ---- 23 1.1 --------- 27.405 ---- 50 ---- 7 1.1 --------- 27.185 ---- 46 ---- 7 1.2 --------- 26.965 ---- 45 ---- 9 1.5 --------- 26.359 ---- 61 ---- 22 2.0 --------- 25.586 ---- 136 ---- 0
Results from the shack end of feedline at 37' height
2.0 --------- 29.572 ---- 25 ---- 4 1.5 --------- 28.699 ---- 49 ---- 23 1.1 --------- 27.405 ---- 50 ---- 8 1.1 --------- 27.185 ---- 45 ---- 7 1.2 --------- 26.965 ---- 44 ---- 9 1.5 --------- 26.351 ---- 62 ---- 22 2.0 --------- 25.518 ---- 130 --- 0
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Post by homerbb on Jun 8, 2012 23:36:28 GMT -5
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Post by Sandbagger on Jun 9, 2012 22:10:29 GMT -5
Don't know if that works any better, bt it sure looks cool.....
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Post by homerbb on Jun 10, 2012 15:26:48 GMT -5
I hear ya. That's just what I'm trying to determine. . . It has six of those 1/2 wave radials, now, and six of the littler ones. I know it's hearing the short skip very well.
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Post by homerbb on Oct 30, 2012 20:06:55 GMT -5
A local friend took home the last tubing End Fed Half Wave (EFHW) I had made - the one in this thread. He has enjoyed it immensely enough that he has generated some interests from others who he does radio work for. As a result I have crafted this one for one of the CBers, and may have another to do in the next week or so. If I were keeping it for myself it would have a set of Radials around the base of it, but this customer was very clear that he wanted an EFWA antenna without the radials. I hope you guys like it.
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Post by "Doc"Hammer on Oct 30, 2012 20:33:54 GMT -5
That is too cool. I have an aging Imax that needs help. This would be a usable solution for me! I have the materials so a project is at hand.
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