Antenna tuning problem

[Muzikman54]

I've never had problems before tuning my antenna's. However, I'm in a 2018 Freightliner sleeper now and having SWR issues. I bought a Wilson 2000 with a short post. I mounted it on the mirror with the recommended mirror bracket. Had HIGH SWR's and kept cutting the whip. Soon found out I had grounding issues, and then the whip was too short. I grounded the bracket and reordered a new whip. SWR's got better but still above 3 on all channels. Bought a SWR meter just in case meter on radio was the issue. SWR readings slightly different but still above 3. Tried tilting antenna, putting a 10" extension rod on, tried attaching extension rod to existing 3" rod. Problem not going away.

So I bought a Firestik II to see if the antenna was the issue. Same high readings. The best I could get it is with the 3" extension rod and tuning screw all the way down. Readings are Channel 1 - 2.65 and Ch 40 - 3.12. I've followed all the suggestions online about re-calibrating on each channel each time you tune, and putting red plastic tip back on each time you tune. I'm at a loss of how to get this damn thing below 2! I have the recommended coax and have tested for continuity on antenna and coax. That doesn't seem to be an issue. Coax is loose on the dash and not wound. I tune with the door closed and windows up.

What is next, cutting the wire on a tunable tip?? I'm afraid I'm going to cut it too much and then have to buy a 3rd one.

Please help. I've tested on a Cobra 29 Classic and Uniden Bearcat 980SSB. But I know the antenna is tuned to the truck, not the CB.

Dave

 

[slowmover]

Test coax for damage:

Won’t hurt to test antenna mount for DC Ground:

Now, proper assembly order is crucial:



The “problem” if above is okay is that the mirror is mounted on the door, not the body.

“Ground” isn’t 12V DC, per se, it’s RF, a different critter.

Youll need to jump both door hinges with woven copper braid. And another to closest bolt on windshield header.

Youve an “old model” Cascadia. Below is drivers door jumper pair on my “new model” (post-2017).



My current antenna setup on a PROCOMM P4 Mount (yours would be P3).

From upper mount bolt is RF BOND as with doors to metal structure under windshield.


Some more RF Bonds are needed, but the first are across doors hinges, and from mount to body steel.

The antenna has to have something against which to push. So to speak. The body is one-half the antenna. RF has to flow (like water) out and back connected to “ground” even though mounting alongside a composite body instead of atop a metal vehicle body sux.

Second part is that one needs the antenna tilted away somewhat from the A-pillar to avoid “reflect”. 15-20/degrees is a maximum where performance is desired.

I had to mount the coil of my antenna on a 44” SS shaft to dial back SWR problem. Now at 11-12/degrees.

Six & Seven foot Skipshooter worked fine at 15-20/degrees before current arrangement. At end, tallest antenna is desirable. 5’ minimum and closest to 14’ total, IMO. (5’ & 6’ give up performance somewhat to a 7’ with best receiver).

What you see is under 1.5:1 SWR.

I bought the tools and supply to make my own bonds. They add up in expense when factory-made.



Link to where I learned the most on my own. This site and a few others also good.

Amateur Radio Install Guide

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[slowmover]

Funny you asked this today. Am doing a 34-reset at a truckstop with a good CB shop. Had tech install co-phase coax this morning as I knew he’d be faster than this old man. 95F today.

Had me a little nap and now it’s time to get out hydraulic crimper & supply to make more bonds for other side. Then front and rear of cab to jump past rear airbags and front bushings.

The effect may be to mainly make the radio rig “quieter”. But the initial work is to help get SWR in ballpark.

Be sure to do your SWR tests away from other vehicles, buildings, trees, etc. An open field (rest area) works well.

Under 2:0:1 is adequate. 1.5:1 is outstanding, but you won’t be able to tell the difference between those.

Bobtail is different than under a trailer. Different trailers present different problems, also. (SWR not accurate until loaded and underway).

From a site I recommend for tech beginnings and reviews:

SWR is only a beginning. An antenna analyzer is how the cow eats the cabbage.

You ain’t alone:

I hate tuning CB antennas

Just curious, is this one of the newer Jeeps with the aluminum body? My last Jeep was a JK so I had plenty of steel to work with.

forums.radioreference.com

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[Muzikman54]

Test coax for damage:

View attachment 148703

View attachment 148704

Won’t hurt to test antenna mount for DC Ground:

Now, proper assembly order is crucial:

View attachment 148708

The “problem” if above is okay is that the mirror is mounted on the door, not the body.

“Ground” isn’t 12V DC, per se, it’s RF, a different critter.

Youll need to jump both door hinges with woven copper braid. And another to closest bolt on windshield header.

Youve an “old model” Cascadia. Below is drivers door jumper pair on my “new model” (post-2017).

View attachment 148705

My current antenna setup on a PROCOMM P4 Mount (yours would be P3).

From upper mount bolt is RF BOND as with doors to metal structure under windshield.
View attachment 148706

Some more RF Bonds are needed, but the first are across doors hinges, and from mount to body steel.

The antenna has to have something against which to push. So to speak. The body is one-half the antenna. RF has to flow (like water) out and back connected to “ground” even though mounting alongside a composite body instead of atop a metal vehicle body sux.

Second part is that one needs the antenna tilted away somewhat from the A-pillar to avoid “reflect”. 15-20/degrees is a maximum where performance is desired.

I had to mount the coil of my antenna on a 44” SS shaft to dial back SWR problem. Now at 11-12/degrees.

Six & Seven foot Skipshooter worked fine at 15-20/degrees before current arrangement. At end, tallest antenna is desirable. 5’ minimum and closest to 14’ total, IMO. (5’ & 6’ give up performance somewhat to a 7’ with best receiver).

What you see is under 1.5:1 SWR.

I bought the tools and supply to make my own bonds. They add up in expense when factory-made.

View attachment 148709

Link to where I learned the most on my own. This site and a few others also good.

Amateur Radio Install Guide

.

Wow! Thanks a lot for this info! Had no idea there was so much involved but I'm going to hash through this step by step to get it done! I checked the coax as described and it's fine. Gonna start with the DC Ground video and go from there. Very much appreciate this!

Dave

 

[slowmover]

You’re welcome.

Radio is in the details.

Todays composite-body tractors are far more difficult in which to install a performing radio system.

1-3/miles ain’t enough distance to get a warning one can work with effectively (route diversion or exit to avoid a pile-up underway at that moment).

Need 2X, 3X that radius of alert.


— The Antenna System is over 80% of what truly matters.

I promise that the more pains-taking you’re willing to be, the greater the rewards.

I’ve had to learn to do, and re-do, on a regular basis as my understanding is bettered, and my willingness digs down deeper.

Spending is part of it. Up to a point. But no matter how much I’ve spent, avoiding danger and/or being ahead of schedule to maybe get an earlier re-load has re-paid my total expense at least two or three times each year.

Other tools (phone & GPS) are aids to atlas, watch & compass. But nothing else comes close to the real time info of two or more trucks on CB defining & solving problems while we’re still moving.


I’ve several threads and a good number of posts. I’m experienced, but I’m not the smart guy around here (very good sub-forum). Here’s a thread as example of defining the problem, and steps taken to deal with that:

SKIP Problems in Noise Abatement.

The discourtesy of screwing up AM-19. The understood Truckers Channel. Got 39 to 119 other channels before we consider freeband. The thread is not to whine and moan, but to introduce others new to CB how to deal with Skip overwhelming local comms. The exigencies of the road. Your experience...

forums.radioreference.com

There is a brand-new circuit board just last year (integrated NRC) which is the biggest change in CB since the introduction of 40-channels. No experience with what DSP is capable means doesn’t know what’s possible.

Promise yourself one of those radios to complement the antenna work:

2023 Best Mobile CB

Via mobile experience as an OTR truck driver. Several thousand hours annual use. Earlier references to the Qixiang factory’s new circuit board elsewhere. Several brands. The above possibly the best known example at present. Paired with the equally new Driver Extreme DRX-9010 External Speaker...

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