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Post by doctor on Jul 18, 2015 10:50:17 GMT -5
I am curious, I have one of those, and the swr around 1.3 to 4.
Anyhow I have the GPK on it, but the other day, I took the GPK off, and noticed NO difference except the swr dropped to 1.1, I left the GPK off.
Anyone else notice any difference with the GPK, just curious.
For the weekend I am on chnl 36 lsb/usb, give us a shout.
DOCTOR/795
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roadrunner
Mudduck
Just got here today. Looking forward to talking to anyone about RF radios and antennas.
Posts: 37 
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Post by roadrunner on Jul 18, 2015 11:19:08 GMT -5
If your I-Max antenna is not higher than 36 feet you will not need any ground radials. Roadrunner
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Post by doctor on Jul 18, 2015 17:12:16 GMT -5
OK ROADRUNNER appreciate it, it is at 22 feet, so no problem...
DOCTOR/795
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Post by BBB on Jul 19, 2015 10:48:21 GMT -5
When I added a GPK to my Imax, I got less comments from the home peanut gallery that I was bleeding into there headphones, speakers and the like. It was about 36-38' from grade to the base of the antenna. The better half could not absorb the look of the long GPK radials so down it came. I use low loss LMR 400 coax and don't start worrying about SWR until above the 2.0:1 threshold (unless the transceiver starts activating power protection measures) Sure I try to adjust what I can to get it lower, but there are just too many other factors at play. Here's a good, but highly technical read about SWR: www.arrl.org/files/file/Technology/tis/info/pdf/q1106037.pdf |
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roadrunner
Mudduck
Just got here today. Looking forward to talking to anyone about RF radios and antennas.
Posts: 37
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Post by roadrunner on Jul 20, 2015 6:27:03 GMT -5
BBB, Thanks for that web site i have never read this one before. Swr is very important to the hole picture but TVI on these kinds of antennas (Fiberglass wire tubes) can be a real big problem to you and the home peanuts. You can get this problem under control just by coiling up that LMR coax cable into a 4'' dia circle with 6 turns. I use tie wraps to hold it all together. This choke in the coax should help eliminate your TVI problems. Roadrunner
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Post by cbrown on Jul 20, 2015 8:37:31 GMT -5
I don't like winding LMR-400 that tight. I usually use 6" as a minimum radius.
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roadrunner
Mudduck
Just got here today. Looking forward to talking to anyone about RF radios and antennas.
Posts: 37
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Post by roadrunner on Jul 20, 2015 9:04:19 GMT -5
Yes your right my mistake, LMR-400 has less of a bending radius. 213 coax works better for this because it's more fixable. Roadrunner
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Post by BBB on Jul 20, 2015 20:12:37 GMT -5
BBB, Thanks for that web site i have never read this one before. Swr is very important to the hole picture but TVI on these kinds of antennas (Fiberglass wire tubes) can be a real big problem to you and the home peanuts. You can get this problem under control just by coiling up that LMR coax cable into a 4'' dia circle with 6 turns. I use tie wraps to hold it all together. This choke in the coax should help eliminate your TVI problems. Roadrunner That's right, I use GAB-Co's butt ugly balun. It even gets the LMR400 green recycled product accessory seal of approval. Notice: Face product away from view for longer lasting results.  |
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roadrunner
Mudduck
Just got here today. Looking forward to talking to anyone about RF radios and antennas.
Posts: 37
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Post by roadrunner on Jul 21, 2015 15:56:35 GMT -5
Remember this picture because it's a good example of a 11 meter choke.
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Post by doctor on Jul 22, 2015 7:23:31 GMT -5
I will remember it. I will have to look around sometime for something about that size for a choke..
doctor/795
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Post by BBB on Jul 24, 2015 11:37:47 GMT -5
I will remember it. I will have to look around sometime for something about that size for a choke.. doctor/795 That's just your basic plastic one gallon windshield washer fluid jug with both ends cut off. The "driving rain flow-thru design" is to help keep things from building nests in there. I poked holes in the jug and ty-wrapped the coax to itself then to the jug to keep the form. I use Jefatech non-flex LMR400. Good stuff: www.jefatech.com/category/d100-ll400 |
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roadrunner
Mudduck
Just got here today. Looking forward to talking to anyone about RF radios and antennas.
Posts: 37
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Post by roadrunner on Jul 25, 2015 11:04:04 GMT -5
BBB, thanks for the tip, i think I will try some of this coax cable.
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Post by whitetail on Jul 26, 2015 6:16:08 GMT -5
BBB, Thanks for that web site i have never read this one before. Swr is very important to the hole picture but TVI on these kinds of antennas (Fiberglass wire tubes) can be a real big problem to you and the home peanuts. You can get this problem under control just by coiling up that LMR coax cable into a 4'' dia circle with 6 turns. I use tie wraps to hold it all together. This choke in the coax should help eliminate your TVI problems. Roadrunner That's right, I use GAB-Co's butt ugly balun. It even gets the LMR400 green recycled product accessory seal of approval. Notice: Face product away from view for longer lasting results. correct me if Iam wrong, does this help with lightning traveling through the coax to your radio? Also should you do the loop just below the connection on the bottom of the antenna? Thanks |
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Post by BBB on Jul 26, 2015 8:42:20 GMT -5
No additional lightning protection is afforded with an ugly balun, and yes, mount it under the base of the antenna or a convenient location on the mast.
My balun is tucked behind my chimney, a few feet below the antenna because if the wife had to look at that thing every day, along with the antenna, it wouldn't exist.
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Post by DJboutit on Sept 6, 2015 16:51:12 GMT -5
I am running a Imax at 52ft foot high I really like this antenna. I made a contact to 853 in Australia on 40usb barefoot here is a video to prove it www.youtube.com/watch?v=CDQdPXF0XeE |
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