CB won't tune

[Miescha]

OK, so I'm sure I'm goofing up something, but I can't figure it out.

I have a Cobra 75 wxst and a brand-spanking-new Firestick Firefly 4ft with tuneable tip. I also ordered the hood groove-mount kit with 18ft of Firestick cable and mounting stud. I also ordered the Firestick quick disconnect and an SWR meter with cable.

I mounted the antenna, ran the cable into the cab, connected the coax connector including soldering the wire tip, then made the connection at the radio box and powered it up. I can hear others just fine and I can get out just fine (tested a few times with StlCruiser and we could talk a mile or two away), so I know it will work for trail use, but here is the problem.

When I hook up the SWR meter and test following the procedure in the Firestick SWR book CoxCB sent me, I get readings WAY in the red. Channel 1 is about 3.2 / channel 19 is about 4 and channel 40 is about 4.8

I played with the antenna tip extension but no amount of screw in/out seems to matter. The SWR book states that a reading higher on 40 than on 1 indicates a 'short' antenna and I should lengthen it. Alternatively, it says a very high reading (in the red as I have) indicates a very poor ground plane or cable fault. I've checked my cable connections for continuity and everything checks out fine. I"m just wondering if I did something wrong putting the cable connector on the end.

Any thoughts (other than ditch the CB and move to Ham)?

[FJ40_owner]

Originally Posted by Miescha

OK, so I'm sure I'm goofing up something, but I can't figure it out.

I have a Cobra 75 wxst and a brand-spanking-new Firestick Firefly 4ft with tuneable tip. I also ordered the hood groove-mount kit with 18ft of Firestick cable and mounting stud. I also ordered the Firestick quick disconnect and an SWR meter with cable.

I mounted the antenna, ran the cable into the cab, connected the coax connector including soldering the wire tip, then made the connection at the radio box and powered it up. I can hear others just fine and I can get out just fine (tested a few times with StlCruiser and we could talk a mile or two away), so I know it will work for trail use, but here is the problem.

When I hook up the SWR meter and test following the procedure in the Firestick SWR book CoxCB sent me, I get readings WAY in the red. Channel 1 is about 3.2 / channel 19 is about 4 and channel 40 is about 4.8

I played with the antenna tip extension but no amount of screw in/out seems to matter. The SWR book states that a reading higher on 40 than on 1 indicates a 'short' antenna and I should lengthen it. Alternatively, it says a very high reading (in the red as I have) indicates a very poor ground plane or cable fault. I've checked my cable connections for continuity and everything checks out fine. I"m just wondering if I did something wrong putting the cable connector on the end.

Any thoughts (other than ditch the CB and move to Ham)?

Ohm meter the cable with the antenna and radio disconnected. There should be no resistance between the shield and center conductor.

Ohm the tip of the PL259 to the shield at the antenna. There should be no resistance.

The higher the frequency ie channel 40 @ 27.405 Mhz the shorter the antenna. So assuming your coax is good as well as your PL259 solder job with a high SWR I would shorten or turn down the screw.

If you have all new equipment and the SWR is not reacting properly and the coax is good you may need to look at your installation. Is there continuity from the shield at the PL259 to the chassis and all the way to the antenna mount? Try installing the antenna in a different location, have a good bond between the car frame and antenna mounting hardware.

Same frustrations apply to Ham radio as well.

Good luck

[Jerry D.]

Yes, check the cable first. Only I believe you should have infinite resistance between the PL259 tip and shield. A “no resistance” to me is zero ohms which would show a short in the coax or connector.

You should make sure the small metal box where the coax/power and mic are connected is also well grounded.

How is the antenna mounted??? Pics???

Jerry D.

[Miescha]

I'll try to get a pic of the mount install, but it is dark now so may not work. The mount is a hood groove mount by Firestick. It is the MK-174 as shown here:

http://www.walcottcb.com/firestik-mk...kit-p-311.html

I've checked (and triple checked) that the antenna side 'fire ring' and assorted stud, washer, lock washer, etc... is in the correct order and the ridge of the ring is facing the correct direction. I've also made sure all connections are tight.


It is mounted using a factory nut/bolt on the PS just forward of the power am/fm antenna - as recommended by Toyota 4WD Owner Magazine and shown (partly) in the pic below. I did not remove the cruiser's paint at the mount point (and would rather not). I'll try to get a pic of my install given the darkness and post later.

I didn't think about the ground at the metal box - I'm currently testing with it loose inside the cab (easier to make connections for SWR meter without it mounted). If this is a likely cause, I may have found the problem. I'll have to reconsider my planned mounting location as I'm not sure it will provide much ground for the metal box. I'll start looking for a good mounting location in the DS under-dash / footwell area.

I think the only possible causes (outside the highly unlikely bad antenna or bad SWR meter) are

1) Bad/incorrect conection of cable connector at radio side (bad solder, short, etc . . .). I'll go through all the continuity / ohm tests again.

2) Lack of good ground at antenna mount (I could try running a 12 guage wire to the frame).

3) Lack of good ground at the radio's metal box (I'll find a better mounting location and bolt the sucker down tight).

[Miescha]

OK, I froze my hands but I managed to check everything noted. First, I found this from Firestick regarding continuity:

There is a minimum of four priorities with every GP antenna installation.

1. No continuity from the coax connector center pin to the coax connector housing while disconnected from the radio.
   
2. No resistance continuity from the coax connector center pin (disconnected at the radio end) to the base of the antenna.
   
3. No resistance continuity from the coax connector housing (disconnected at the radio end) to the antenna mount.
   
4. Final SWR reading below 3.0:1 on any channel that you use.

Upon testing, I have NO CONTINUITY from the PL259 center pin to the threaded housing. Ohm reading was 00.4

I also have NO CONTINUITY from the PL 259 center pin to the MK174 base of the antenna. Ohm reading was also 00.4

I also have NO CONTINUITY from the PL259 threaded housing to the antenna stud mount (or anywhere else on the antenna).

There IS continuity from the PL259 center pin to the antenna stud and everywhere else on the antenna except the the MK174 base, as noted above.

There IS continuity from the PL259 threaded housing to the MK174 base.

There IS continuity from the MK174 base to the chasis ground (I used the battery negative terminal as a test point, as it has a direct ground to the engine block and chasis).

There IS continuity from the PL259 threaded housing to the chasis ground (batter neg. terminal test point again).

There IS continuity from the threaded antenna connector on the radio metal box to the chasis ground (neg battery terminal test point again).

I can't get a good photo of the mount as it is too dark (the flash reflects off the vehicle paint and bounces back).

At this point, I'm wondering if I'm using the meter wrong. I have it connected between the antenna and the radio as indicated in the accompanying literature. I set it to "FWD" then key the mic on channel 1, while holding the mic keyed, I adjust the knob to the extreme far right of the band where the words "set" appear. While still holding the mic keyed, I flip the meter switch from 'FWD' to 'REF' and read the SWR. I repeat this on channels 19 and 40. It always stays well above 3 as noted in my first post.

I also mounted the antenna on the top tab of my ARB front bumper (my preferred location as that tab is VERY stout) and I tried a rear hatch location (b/c I have the MK 204 mount just in case I didn't like the MK174 location). I found NO DIFFERENCE in any of the locations. Given this, I'm tempted to just mount it on the ARB as I would like and call it a day. There is definately a good chasis ground at the ARB location despite the powder coat paint, but I guess I'll have near zero ground plane - but maybe it doesn't matter b/c my SWR is so high anyway.

I have to be up at 5am, so I only have a few more hours to figure this out and pack my stuff into the cruiser. I'm starting to think maybe the meter IS bad

[Miescha]

Yep, I'm an idiot

I decided to follow my usual problem solving theory which states that if whatever I'm attempting to accomplish is not working correctly, I'm probably doing something wrong somewhere.

I deciding that given a WAY high SWR no matter where I mounted the antenna, I would prefer to have it on the ARB front bumper. I moved it to the PS top-most tab and began checking everything again. This time, I had no chasis ground from the ARB top tab (my new 'mount' point) and therefore no continuity from the radio-end PL259 threaded housing to the tab. This is a definate bummer.

I had already removed the MK174 mount, but decided to re-check the ground at the hood groove where it was previously mounted. No chasis ground. Big bummer. I then check for chasis ground at the exact OEM bolt I used. No ground. I then checked at the washer of the OEM bolt I was using and got a continuity signal back to the battery neg terminal. Big relief. Still, it seems clear that to get a good ground here I would need to remove some of the paint or run a wire from the MK174 base back to the neg battery terminal.

Instead, I decided to run a 12 guage wire (I didn't have anything bigger on hand) from the ARB base back to my PS second battery neg terminal (grounded to the PS ground point on the engine). This was tougher than planned b/c the coax that comes with the MK174 kit does not have a seperate ground wire, so I had to ground to the inner 'Firering' ground point without also grounding the bolt or mouting stud. After a ton of continuity testing, I managed to get it.

So the moment of truth, I wire up the SWR meter and key the mic on channel 1 and get a reading of 1. Yep, SWR was 1 on channel 1. On channel 40 it was up over 2 and after a lot of tuning the Firefly tip, I ended up with 1.8 on channel 1 / 1.5 on channel 19 / 1.8 on channel 40. I figured this was a nice 'dip curve' and decided to call it a night (I still have to pack up my trail gear in the cruiser and hopefully find something to pack for lunch tomorrow).

I hope I haven't just found a nice way to fool the SWR meter without the associated gains in signal strength, but I did notice a much clearer signal coming in across all the channels.

Thanks a ton for the advice guys, I hope future readers find this thread and are helped by my follies.

[Jerry D.]

Glad you got things looking right, now if only you had a field strength meter...

Jerry D.

[Miescha]

Originally Posted by Jerry D.

Glad you got things looking right, now if only you had a field strength meter...

Jerry D.

It never ends does it?!