Homemade quarter-wave ground plane base antenna

**mattsowders1989** · 10-07-2016, 06:04 PM

the coax i use is R & L Electronics RG 8/U .80 2015 Low Loss.

**mattsowders1989** · 10-07-2016, 09:12 PM

Better yet, what is the best, cheapest thing I can do about my coax and antenna? I have next to no money I can spend. If I knew what I had to do exactly to make what I have work correctly, I would do it. The Drake matching network just won't work with 11-meters. I've measured my coax and have it the correct length. Maybe my radials aren't at the right angle? I know they are close to a 45 degree angle. It's just very aggravating because one, I have taken so much of your time, Sean, and two, I've put a lot of work into my base setup. I just want it to work right.

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**mattsowders1989** · 10-07-2016, 09:13 PM

I had already downloaded a manual for the Drake unit, I just needed some radio expertise

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**222DBFL** · 10-07-2016, 10:20 PM

Try a 1:1 matching balun at the feedpoint of your antenna as your VSWR might be good but your impedance might be out of whack and not near 50 ohms as it should be. Also a 1:1 balun will help with any CMC issues that may be present on the coax. And also always measure the VSWR without the amp in line. There is more to tuning an antenna than just VSWR. Impedance, resistance, and reactance as well as VSWR all need to be good. Impedance matching is just as important as VSWR. As I said your VSWR may be good but is it at or near 50 ohms. This is where an antenna analyzer helps a bunch!! But a 1:1 matching balun may help this issue. And no your amp coax jumper should not have to be a 1/2 wave length. Make it reach from amp to radio. If it's bad when the amp is off, you most likely have other issues. Like CMC along the coax or an input/output issue with the amp with impedance being mismatched creating a bad VSWR. Get a 1:1 balun and try that. Or some snap on ferrite chokes, read up on the use of them as well as the 1:1 balun. You might be able to make a coil choke with your coax as well sand help. Read up on how to match impedance. And now it correlates with the VSWR readings you see now. I am down and out for now as it got pretty bad here with the hurricane that went through!! Man we got worked!!! Anyhow,'try to study some of the info I have given you. And have a good one!!

**mattsowders1989** · 10-10-2016, 11:43 AM

Ok. Thank you sir.

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**mattsowders1989** · 10-10-2016, 08:24 PM

I hope your equipment didnt get too damaged!

**222DBFL** · 10-11-2016, 01:57 AM

Damage is not bad. Antenna is bent a little from a fast take down. But it can be fixed or replaced. Other than that I have all my radio and other equipment still. Will rebuild. Just takes time to do it correctly. Going to be using LDF4-50A heliax coax this time. A step up from LMR400. Very low loss coax!! And also will be using a different mast/tower system. But I will get it done. No worries!! Might take me a little while. But when I am done it will be a solid setup that should work quite well!!!

**mattsowders1989** · 10-11-2016, 07:18 AM

That's good. I don't have the money yet but I'm going to get an antenna analyzer as soon as I can. I got my SWR down to between 1:1 and 1.1:1. Still getting an antenna warning message on the cobra but that is only with my transistor linear on high putting out 150 watts. I noticed that with this amp I am using, I'm getting a backward swing. I dead key with the amp and 150 watts and when I modulate, it swings to about 130. The radio is a cobra 29 LX. It is factory stock. Never been peaked or anything. Not sure why it's doing that but the locals (about 15 to 20 miles away), tell me I sound crystal clear.

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**JesseJamesDallas** · 10-11-2016, 07:34 AM

What is your dk on the cobra set at? If it's under 3w that's why you get the antenna warning message... although a backward swing is usually due to a high dk.