Help tuning CB radio antenna

jazngab said:
So that’s a lot of fancy cb talk for a noob like myself. What do you suggest I try to do to remedy my situation? I’ve tried understanding this ground plane concept but I’m not getting it.
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If your match is good at band center, but bad at the band edges then I would suggest just getting a longer Firestik. If it is bad everywhere then you are probably looking at a combination of grounding, placement, proximity effects, etc.

BTW, just because an antenna is tuned to resonance, it is not necessarily 50 Ohms. A quarter wave antenna on a perfect ground plane will be around 35 Ohms at resonance which will yield a VSWR of 1.5:1. However, I believe that antennas like Firestiks are designed to be near 50 Ohms at resonance using a combination of non-linearly wound inductors or other magic tricks.
 
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This is a 3 foot Firestik on my Jeep. It is mounted to my homemade Rotopax mount on the tire swing. It is good for 1.5:1 at the band edges and is nearly perfect at band center.

3 foot Firestik.jpg
 
The fact that SWR improved when you sanded some additional paint indicates that proper grounding of the antenna mount and antenna bracket may be your primary issues. You should continue to focus on that.

Your comments about the ohmmeter suggest that you have not yet followed all of the troubleshooting tips in the provided links, many of which require the use of that tool. You should follow those procedures.. (Note: testing for continuity will tell you whether or not you have an electrical connection, not how strong a radio frequency ground may be - that will require experimentation as you add ground straps.)
 
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TurboTJ said:
This is a 3 foot Firestik on my Jeep. It is mounted to my homemade Rotopax mount on the tire swing. It is good for 1.5:1 at the band edges and is nearly perfect at band center.

View attachment 84799
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How is your mount grounded to the tub?
Mr. Bills said:
The fact that SWR improved when you sanded some additional paint indicates that proper grounding of the antenna mount and antenna bracket may be your primary issues. You should continue to focus on that.

Your comments about the ohmmeter suggest that you have not yet followed all of the troubleshooting tips in the provided links, many of which require the use of that tool. You should follow those procedures.. (Note: testing for continuity will tell you whether or not you have an electrical connection, not how strong a radio frequency ground may be - that will require experimentation as you add ground straps.)
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Thanks. I’ll try and continue to troubleshoot.
 
jazngab said:
How is your mount grounded to the tub?
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Actually, it is not grounded to the tub at all. The metal Rotopax mount is bolted to the tire swing and the only ground connections are through the swing axle and latch at the other end, both of which are bolted to the bumper. The bumper in turn is bolted to the frame.
 
@jazngab, did you ever drill that other hole on your mount? If not it won’t keep the mount pressed against the tub sufficient for good grounding at that location.
 
JMT said:
@jazngab, did you ever drill that other hole on your mount? If not it won’t keep the mount pressed against the tub sufficient for good grounding at that location.
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I haven’t yet. Is it possible that an extra hole can be ground it better than the 3 holes that are already grounded?

MaloStapalo said:
I am mounting on my swing out carrier and was recommended to run tinned copper grounding strap to the body from the antenna.
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Yea I’m looking at those copper straps. Leaning towards buying them off amazon.
 
jazngab said:
I haven’t [drilled the other hole in the mount ]yet. Is it possible that an extra hole can ground it better than the 3 holes that are already grounded?
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Absolutely.

As stated in Post #4:

I note that you did not use the upper hole in the Teraflex bracket that requires drilling a hole in the tub. This may be contributing to your issues. I used the hole that you left unused, drilled through the body, then sanded a small ring around the hole on both the inside and outside of the tub and on both the inside and outside of the bracket to ensure a good metal-to-metal bond between bracket and tub.

If you are relying entirely upon the fasteners for the taillight housing not only is your bracket substantially weaker than if you used the upper hole, the electrical bond between bracket and body will be marginal at best.

Don't fear the drill. That hole is there for a reason.
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Here's my $.02 on this subject and I apologize if someone has already suggested this. My buddy was having the same problem and I could not get SWR reading below 2.5 no matter how I grounded it. I finally put my antenna on his and it worked perfect. Unless you know your antenna is good, you may want to put another one on. Either a buddies or buy one, they aren't that expensive.
 
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Igoo65 said:
Here's my $.02 on this subject and I apologize if someone has already suggested this. My buddy was having the same problem and I could not get SWR reading below 2.5 no matter how I grounded it. I finally put my antenna on his and it worked perfect. Unless you know your antenna is good, you may want to put another one on. Either a buddies or buy one, they aren't that expensive.
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It’s crossed my mind as well. Trying a different antenna that is.
 
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jazngab said:
I haven’t yet. Is it possible that an extra hole can be ground it better than the 3 holes that are already grounded?
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I know you don't want to drill that hole in the tub. I didn't want to either. If you are absolutely opposed to drilling that hole, try another antenna first, then if that doesn't resolve your problem, drill the hole. I'm getting 1.5 SWR reading on a 3' Firestik. A buddy of mine runs a 2' Firestik with the rest of the setup the same, both working fine, not sure what his SWR readings were.
 
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You could check your antenna bracket ground with an ohmmeter before you drill the hole.
 
Is your antenna and coax a “no-ground-plane” setup or a ground plane one? Just curious, mostly because I didn’t see it mentioned.
 
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