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High SWR on All New CB Setup

dlhanse

Newbie
Joined
Oct 8, 2024
Messages
2
Hi. New to the hobby. Installed new CB system on Ford Ranger Truck. Getting very high SWR reading above 3.0.

All equipment is brand new. Antenna tests good. Have tried 2 different radios and 3 different antennas, and 3 sperate cables.
Coax cable tests good, no short, no breaks.
Mounting bracket is grounded properly, no shorting across nut. Good isolation between antenna and bottom nut. Grounded to chassis with 8" long ground cable, and also mounted directly to metal. Continuity confirmed with meter from mounting bracket and negative battery terminal.
Antenna (2' fiberglass) mounted near the rear of truck on the top of the bed wall. Not close to cab in open air. Sticks above cab 10".
SWR tested in open field.

What else can I do?

Thanks
 

nokones

Newbie
Premium Subscriber
Joined
Feb 19, 2011
Messages
612
Location
Sun City West, AZ
Hi. New to the hobby. Installed new CB system on Ford Ranger Truck. Getting very high SWR reading above 3.0.

All equipment is brand new. Antenna tests good. Have tried 2 different radios and 3 different antennas, and 3 sperate cables.
Coax cable tests good, no short, no breaks.
Mounting bracket is grounded properly, no shorting across nut. Good isolation between antenna and bottom nut. Grounded to chassis with 8" long ground cable, and also mounted directly to metal. Continuity confirmed with meter from mounting bracket and negative battery terminal.
Antenna (2' fiberglass) mounted near the rear of truck on the top of the bed wall. Not close to cab in open air. Sticks above cab 10".
SWR tested in open field.

What else can I do?

Thanks
If you are using a Firestik, is it a Firestik II with an adjustable tip? A 4 Ft Antenna would work a lot better on the VSWRs but a 5 Ft. would be better. What VSWR readings are you getting on Ch. 1, Ch. 20, and Ch. 40?
 

WSAC829

Member
Joined
Jan 13, 2024
Messages
123
Location
Green Bay
That antenna is too short to tune properly. You need at least a 4 foot antenna for a good swr.
I beg to differ. I use a 3 foot Diesel whip on my F150 with a hood/fender mount. It has a super low SWR across all 40.
 

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slowmover

Active Member
Joined
Aug 4, 2020
Messages
2,740
Location
Fort Worth
Tuning Guide

Welcome! Some images wouldn’t hurt. Most problems are mount type & location. As above, it’s the sheetmetal underneath that is one half of the antenna.

I wouldn’t get too hung up on total length at beginning, but . . . .

Low SWR is “nice” (@ 1.5:1), but total antenna length is an equivalent to performance. One might hear “okay”, but to expect to be heard, a 5’ is where reasonable performance begins.

A quarter-wave antenna is 9’. Staying above half that length is best.

7’ is where best design/manufacture creates an antenna better suited to the high wind loads of mobile operation. Whether a base load SIRIO 5000 or a mid-coil PREDATOR 10K-1-27 is chosen is almost a preference, now is performance optimized without the wind whip of a 108”.

Static mobile to mobile is a nice stand-in as a test, but it’s clarity at greatest distance while underway where one learns that (first), there’s no substitute for height, and (second) that antenna particulars matter.

A SIGNAL ENGINEERING GR 45 is a partial exemption in length given its top hat design. Not as tall as the two above, but more likely to catch against obstacles if not careful. With a fairly ordinary radio it gets outstanding reports.

An all-around best start is a 6’ Skipshooter. Not as flexible as the 7’, but with very good top load performance that’ll put any 3-4’ antenna to shame. “Clear” cover stands out least, and it’s a low price

Not for nothing I learned to buy this brand in pairs (big truck).

OP, FWIW, I ran a mag mount on the pickup roof for many years. Location trumps almost all else, just ahead of total height.

If you expect to hear and be heard about a mile or so, it’s not hard to get going. If you want real performance, it’ll take more planning and work. A mile isn’t enough in high speed rural traffic.

— Stick around long enough to work through a good solution for what you have right now. Report back to keep working details.

.
 
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robertwbob

KE0WRU
Joined
Nov 17, 2015
Messages
372
Location
Northeast jasper county,missouri
bad vswr meter or bad jumper.unless your using built in vswr meter. that many changes should produced diffrent results. we are not there so walk us through whole process . i think we are missing a link or 2 in your setup. can you hear other radios?
oh if you can remove coax from antenna with ease check continuitu. might be 1 thin wire from braid touching center wire post in pl259
 

dlhanse

Newbie
Joined
Oct 8, 2024
Messages
2
Tuning Guide

Welcome! Some images wouldn’t hurt. Most problems are mount type & location. As above, it’s the sheetmetal underneath that is one half of the antenna.

I wouldn’t get too hung up on total length at beginning, but . . . .

Low SWR is “nice” (@ 1.5:1), but total antenna length is an equivalent to performance. One might hear “okay”, but to expect to be heard, a 5’ is where reasonable performance begins.

A quarter-wave antenna is 9’. Staying above half that length is best.

7’ is where best design/manufacture creates an antenna better suited to the high wind loads of mobile operation. Whether a base load SIRIO 5000 or a mid-coil PREDATOR 10K-1-27 is chosen is almost a preference, now is performance optimized without the wind whip of a 108”.

Static mobile to mobile is a nice stand-in as a test, but it’s clarity at greatest distance while underway where one learns that (first), there’s no substitute for height, and (second) that antenna particulars matter.

A SIGNAL ENGINEERING GR 45 is a partial exemption in length given its top hat design. Not as tall as the two above, but more likely to catch against obstacles if not careful. With a fairly ordinary radio it gets outstanding reports.

An all-around best start is a 6’ Skipshooter. Not as flexible as the 7’, but with very good top load performance that’ll put any 3-4’ antenna to shame. “Clear” cover stands out least, and it’s a low price

Not for nothing I learned to buy this brand in pairs (big truck).

OP, FWIW, I ran a mag mount on the pickup roof for many years. Location trumps almost all else, just ahead of total height.

If you expect to hear and be heard about a mile or so, it’s not hard to get going. If you want real performance, it’ll take more planning and work. A mile isn’t enough in high speed rural traffic.

— Stick around long enough to work through a good solution for what you have right now. Report back to keep working details.

.
I made a short video

 

Varmonter

Member
Joined
Jun 24, 2022
Messages
56
Location
Anywhere usa
I'll chime in a bit.. a 1/4 wave 11m antenna should measure 103.2 inches mid band..Anything shorter is a compromise..Truth be known I didn't even know a 2ft cb antenna exists.. I have a 102 wip on a 6 inch extention on a ball mount. I'm probably 112 inches total. My swr is 1.03:1 pretty Flat across the whole band and it's on a magnet mount..(not ideal) anything shorter with wire wound around fiberglass is a compromise..If you need a short antenna I would reccomend a serio performer..I'm thinking your 2 foot antenna may be for some other band..
 

prcguy

Member
Premium Subscriber
Joined
Jun 30, 2006
Messages
16,312
Location
So Cal - Richardson, TX - Tewksbury, MA
The video says the mount is grounded to the bed wall sheet metal and if that is true it should tune up and work fine. The ground wire to the chassis is meaningless to the antenna and it only cares about the coax and mount being grounded to the sheet metal at the mount.

I would leave the mount screwed to the bed wall and disconnect everything from the mount including the ground wire and test the following:

Check continuity from coax center pin at the radio end to center pin at the antenna, it should be shorted.

Check continuity from coax center pin at radio end to coax shield at radio end, should be open.

Check continuity from mount to a grounded point in the bed like bolts at the tailgate, on the tail light, should be shorted.

Check the white insulator and hole in the mount, the hole in the mount should be 1/2” and the hole in the insulator should be 3/8”. The insulator should have a lip pointing down to center it in the larger hole in the mount so the mounting bolt that goes through the insulator is floating and doesn’t short to the mount.

If all checks out ok then reassemble without the ground wire and check for continuity from the center pin at the radio to the antenna stud, should be shorted.

Then check center pin to coax shield at the radio end, should be open.

If that checks out the antenna should tune up and work fine.

If not disconnect the antenna and temporarily connect 108” of bare wire to the antenna stud and hold that up and away from the truck with some string to a tree, etc. That should show a very good match. In this case you have an antenna problem and you might look for a replacement.

If the wire didn’t work you’re cursed. Bring it to me in So Cal and I’ll figure it out.
 

Varmonter

Member
Joined
Jun 24, 2022
Messages
56
Location
Anywhere usa
Have you checked continuity between the bottom of the spring and your antenna..basically bypassing the spring .Springs have a wire inside so when it flexes you don't lose contact. They are notorious for going bad..even when brand new..
You might try just removing the spring and checking your swr..with just the antenna..The spring is really doing nothing. A 2ft antenna (like any short antenna) is electrically 1/4 wave with the windings.The spring is adding 4 inches to this measurement.and since it doesn't stick up over the cab (which it should) your probably not going to hit much with it.
Also (if you don't know) you should not test swr in your garage.it should be out in the open like in a parking lot.
The ground wire is doing nothing and may mask continuity issues elsewhere..it's rf ground not DC ground we are after.
Pardon me if you already know or have done all this..
 
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