SWR on homebuilt Yagi
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| Jun 11th, 14:59 | |
rdallen56@charter.netTotal Topics: 0 Total Posts: 0 |
I built a tape measure yagi antenna to try to better my satellite comms with an HT. I built a dual band 2m/70cm.It has 4, 2m and 7 70cm elements. I used old CB coax jumpers to solder in my coax jumpers. The jumper on the 2m side is 16 inches. My SWR on 2m is 1.2:1. The jumper on the 70cm side is 24 inches. The SWR on 70cm I can't get below 3:1. Do I need to shorten this coax length? Do I need to shorten/lengthen (?) the spacings of the elements? My element spacing on 2m is 12 3/8 inches, and on 70cm they are at 5 inches. I have been a HAM operator for a whopping 6 weeks, so to say I'm new at this is a mouthful. Any help would be appreciated. Thanks, Ralph KK7SXE |
| Jun 14th, 11:19 | |
jmcauliffeTotal Topics: 0 Total Posts: 0 |
What Coax are you using? If you are using RG-58 or something similar it will cause the high SWR condition. You want something like LMR400. Also in the future please submit questions to tis@arrl.org or call using our phone number. John Digital RF Engineer ARRL Lab |
| Yesterday, 09:13 | |
N7JCTTotal Topics: 0 Total Posts: 0 |
I'm curious to know how this came our for you Ralph. Any success? I agree with John that you should have better luck with LMR400 or similar. You can, and at some point maybe should, go down a rabbit hole exploring things like the velocity factor of the coax used, the reactances, and all that. But to get get the rubber on the road I've often just grabbed some other type of coax, made the same stub, and experimented to see how it performed differently. Trial and error stuff, that can be a fun way to learn. |
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