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Posted: 9/16/2020 7:16:14 PM EDT
SWR is 1.1-1.2 across the VHF band
I threw it 60 feet up in a tree and is twice the height of my Diamond 22A. I am amazed how well it works even with an HT. Height trumps power. Mine does not roll up though, I made it for the home QTH from a 65 inch piece of 1/2 inch PVC I had laying in the scrap pile and 10g solid copper wire instead of window or 300 ohm line. I think the extra wide separation of the wires made it more wide band. This was an experiment so it is held together with electrical tape. I am going to make it a sturdy and make it my primary VHF antenna.  Attached File |
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Posted: 9/16/2020 7:31:22 PM EDT
[#1]
Very cool! There's a thrill to making your own antenna and making that first contact.
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Posted: 9/17/2020 8:35:27 AM EDT
[#2]
This is an area of interest. I would like to see more home brew antenna write ups...
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Posted: 9/17/2020 10:26:41 AM EDT
[#3]
Quote HistoryQuoted: This is an area of interest. I would like to see more home brew antenna write ups... I followed this but instead of using 450 window line or 300 ohm TV line, I used a 1/2 inch PVC pipe and 10 gauge solid copper wire using the PVC pipe as the wire separator. I am currently looking for a 65 inch flat rigid piece of plastic or something that is lighter so I can use plastic ties to keep the wires in place instead of electrical tape. https://www.hamuniverse.com/2meter300ohmslimjim.html  Attached File |
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Posted: 9/17/2020 8:18:13 PM EDT
[#4]
Cool. I just made a 1/4 wave ground plane for 2m. Tomorrow I'm doing a coax dipole. Then I'll see what kind of SWR I have.
decided to finish today. at 146.520 Coax dipole gets 2.70, ground plane is 7.50 time to do more reading and try to find out where I went wrong.I think I know |
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Posted: 9/17/2020 11:50:13 PM EDT
[#5]
Post details about what you made, maybe we can help.
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Posted: 9/18/2020 12:54:36 AM EDT
[#6]
Quote HistoryQuoted: Post details about what you made, maybe we can help. +1 |
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Posted: 9/18/2020 12:56:50 AM EDT
[#7]
alrighty.
The vertical dipole used these plans: link used 25' instead of 7 meters of RG58 Ground plane is this one 12 gauge solid copper. where i think i went wrong is, i left the insulation on and only stripped where a metal to metal contact is made. all 5 elements are 19.20"end to center of hole. all elements are a single 44" piece, bent in half then twisted together with drill, giving 2 12ga conductors. and I just had a thought, i dont think the radiator element legs are touching each other at the bottom, so it's seeing about 40" of copper wire instead of 19". |
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Posted: 9/18/2020 1:29:48 AM EDT
[#8]
Quote HistoryQuoted: ...I just had a thought, i dont think the radiator element legs are touching each other at the bottom, so it's seeing about 40" of copper wire instead of 19". How were you supporting the antennas when you measured the swr and what was the resonant freq? For both of those you'd trim the radiator to get the resonant point correct, say 146MHz, and then trim the radials to get the swr minimized. The coaxial dipole is hard as the shield has a different velocity factor than the conductor so the lengths are different. Personally I'd fold the shield back instead of the ugly Balun or at least substitute an appropriate ferrite. If you fold the shield back you can double it back at the bottom to make it easier to get the length right. I do that by first trimming off the insulation and then scrunching the shield down and milking it over itself. If you don't completely milk it all the way down it will give you the kind of z fold. It also takes more than you think so start long. |
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Posted: 9/20/2020 4:14:28 PM EDT
[#9]
Mach, I built basically the same thing, from these plans:
https://please.name.my/111/howto-2-meter-slim-jim-antenna-from-ordinary-wires.html 12 gauge wire, the pipe, rg174 cable to the ht, spade connectors at the wire. Putting it up with another section of pvc, maybe 20ft of height. It's the first antenna I've made that actually improves gain. With this and a Baofeng UV-82hp, on 5 watts, I'm talking on repeaters 45 miles away. |
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Posted: 9/20/2020 8:21:38 PM EDT
[#10]
Quote HistoryQuoted: Mach, I built basically the same thing, from these plans: https://please.name.my/111/howto-2-meter-slim-jim-antenna-from-ordinary-wires.html 12 gauge wire, the pipe, rg174 cable to the ht, spade connectors at the wire. Putting it up with another section of pvc, maybe 20ft of height. It's the first antenna I've made that actually improves gain. With this and a Baofeng UV-82hp, on 5 watts, I'm talking on repeaters 45 miles away. That's impressive. I'm not getting that from a Comet CX333 at 40ft with 25 watts. I might be bending up some 6 gage ground wire and trying one on VHF myself. I have already made one for GMRS but haven't received the LMR-400 I want to use to hook it up. |
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Posted: 9/20/2020 11:04:07 PM EDT
[#11]
Quote HistoryQuoted: Mach, I built basically the same thing, from these plans: https://please.name.my/111/howto-2-meter-slim-jim-antenna-from-ordinary-wires.html 12 gauge wire, the pipe, rg174 cable to the ht, spade connectors at the wire. Putting it up with another section of pvc, maybe 20ft of height. It's the first antenna I've made that actually improves gain. With this and a Baofeng UV-82hp, on 5 watts, I'm talking on repeaters 45 miles away. yep it works very well I am about to make version 2.0 |
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Posted: 9/20/2020 11:11:45 PM EDT
[#12]
Quote HistoryQuoted: yep it works very well I am about to make version 2.0 Try add a phasing stub/coil plus another half-wave element on top of the first one and give it some gain. |
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Posted: 9/21/2020 12:35:20 AM EDT
[#13]
Quote HistoryQuoted: I followed this but instead of using 450 window line or 300 ohm TV line, I used a 1/2 inch PVC pipe and 10 gauge solid copper wire using the PVC pipe as the wire separator. I am currently looking for a 65 inch flat rigid piece of plastic or something that is lighter so I can use plastic ties to keep the wires in place instead of electrical tape. https://www.hamuniverse.com/2meter300ohmslimjim.html https://www.AR15.Com/media/mediaFiles/98989/slimjim300ohm_jpg-1595105.JPG How important is it to follow that exactly? Seems it would be quicker, easier, more secure physically and electrically, to use a single conductor wrapped around, as shown here?  Attached File |
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Posted: 9/22/2020 5:39:19 AM EDT
[#14]
Quote HistoryQuoted: How important is it to follow that exactly? Seems it would be quicker, easier, more secure physically and electrically, to use a single conductor wrapped around, as shown here? https://www.AR15.Com/media/mediaFiles/32438/jp_png-1600923.JPG Quote HistoryQuoted: Quoted: I followed this but instead of using 450 window line or 300 ohm TV line, I used a 1/2 inch PVC pipe and 10 gauge solid copper wire using the PVC pipe as the wire separator. I am currently looking for a 65 inch flat rigid piece of plastic or something that is lighter so I can use plastic ties to keep the wires in place instead of electrical tape. https://www.hamuniverse.com/2meter300ohmslimjim.html https://www.AR15.Com/media/mediaFiles/98989/slimjim300ohm_jpg-1595105.JPG How important is it to follow that exactly? Seems it would be quicker, easier, more secure physically and electrically, to use a single conductor wrapped around, as shown here? https://www.AR15.Com/media/mediaFiles/32438/jp_png-1600923.JPG that is what I did. I used a single piece of wire and soldered RG-8X to it. I am working on one that has a SO239 coax connector on it embedded in the PVC |
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Posted: 9/22/2020 12:42:53 PM EDT
[#15]
I'm going to try that with some 12 ga and 3/4" pvc.
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Posted: 9/22/2020 1:11:02 PM EDT
[#16]
The designer of the slim jim antenna N9tax Recommends not putting inside pvc.
https://n9taxlabs.com/technical-info |
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Posted: 9/22/2020 1:12:17 PM EDT
[#17]
Quote HistoryQuoted: The designer of the slim jim antenna N9tax Recommends not putting inside pvc. https://n9taxlabs.com/technical-info I'm putting it around, on the outside. |
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Posted: 9/22/2020 2:01:09 PM EDT
[#18]
Quote HistoryQuoted: The designer of the slim jim antenna N9tax Recommends not putting inside pvc. https://n9taxlabs.com/technical-info I saw that and my wires are on the outside of the PVC, but as far as I know PVC is RF transparent so I don't know why he says that. It might add a small dielectric component, but I don't see why it would be an issue. Maybe I am missing something. ETA: ok he is talking about the antennas he sells because the PVC will change the tuning. That is not an issue when you make it from scratch and you tune it when you make it or you just accept the 1.2 SWR instead of the 1.0 that he tuned it to. |
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Posted: 9/22/2020 2:13:05 PM EDT
[#19]
The Ed Fong ones are different tuned differently depending on whether it's in PVC or in free space.
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Posted: 9/22/2020 3:56:42 PM EDT
[#20]
Quote HistoryQuoted: ETA: ok he is talking about the antennas he sells because the PVC will change the tuning. That is not an issue when you make it from scratch and you tune it when you make it or you just accept the 1.2 SWR instead of the 1.0 that he tuned it to. A few years back I made this big wobbly thing, it's a 2 meter colinear J-pole with two stacked 1/2-wave elements above the 1/4-wave matching stub. It was a pain to tune, and putting it all inside the pipe did shift the resonance point a noticeable amount.  |
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Posted: 9/22/2020 4:11:25 PM EDT
[#21]
Thanks for the clarification everyone.
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Posted: 9/22/2020 9:40:42 PM EDT
[#22]
Quote HistoryQuoted: I saw that and my wires are on the outside of the PVC, but as far as I know PVC is RF transparent so I don't know why he says that. It might add a small dielectric component, but I don't see why it would be an issue. Maybe I am missing something. ETA: ok he is talking about the antennas he sells because the PVC will change the tuning. That is not an issue when you make it from scratch and you tune it when you make it or you just accept the 1.2 SWR instead of the 1.0 that he tuned it to. Yes if you put an antenna inside or next to some kind of plastic or any other insulator that has a different dielectric constant than air, the antenna will be detuned. Anything inside a dielectric radome has to be cut/tuned for that environment. |
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Posted: 9/24/2020 12:47:03 PM EDT
[#23]
Well I can relate an odd tidbit with mine.
When I first assembled it, it worked great, I was very happy. So I went to give it more "permanence", that is, reinforce it for future field use. I put tight zip ties around the whole thing, about 6-8 inches apart, up and down the length, tight. Went back out to use it, it didn't work well at all! I can only surmise that the tightness of the zip ties was distorting the "straightness" of the wires, somehow interfering with things..... Took the zip ties off, made sure wires were nice and straight, went to broad strips of duct tape to secure everything. Tested it again, was working just as before, it is in fact a awesome. Leaving it this way, it's working great. Perhaps some sort of detuning was taking place. Yeah I know, I really should have a SWR meter at very least to continue this kind of experimentation. |
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Posted: 9/24/2020 10:39:36 PM EDT
[#24]
I ade one out of 1/2 copper pipe with a SO239 connector. Very broad band. Usable on the whole 2 meter band.
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Posted: 9/25/2020 9:14:30 AM EDT
[#25]
Quote HistoryQuoted: I ade one out of 1/2 copper pipe with a SO239 connector. Very broad band. Usable on the whole 2 meter band. I just made the SO239 connected to the PVC pipe. The one that I have hanging is very broad band. It covers 2m through MURS and the VHF commercial freqs that I was interested in. |
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Posted: 10/3/2020 9:59:44 PM EDT
[#26]
Quote HistoryQuoted: that is what I did. I used a single piece of wire and soldered RG-8X to it. I am working on one that has a SO239 coax connector on it embedded in the PVC well, I did it. Or most of it anyway. 3/4 pvc, single piece of bare 12ga copper wire. I drilled holes near top and bottom for wire to pass though the pvc. the ends of the wire are .10", not 1". This was on purpose so I can trim to tune if need be, both ends left long. I used a SO-239 for panel mount and made a rubber washer to fit around it, and in a 3/4 pvc T. Soldered some RG-58 to the connector, and left about 12" tail. fed wire though the T until 239 is about flush, then filled the back of it with epoxy resin to hold it in. Works great. Fed the RG up through the PVC and out a hole at the tap point. Tapped them in, and did a quick check. It does hit a 2m repeater that's about 6 miles away, up on a hill (using BF-F8+) 2m swr is great (1.0-1.1), 70cm is good (1.8-2.0) Now I'm going to read up on how to fine tune it for 70cm and not mess up 2m  Attached File Attached File Attached File Attached File |
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Posted: 10/3/2020 10:49:49 PM EDT
[#27]
Nice work!
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