Unable to Transmit / Receive - Thanks for any advice!

[GFPine]

Hello Everyone,

I’m new to the forums but used to have CBs years ago and recently decided to put one in my vehicle. I’ve had a lot of unexpected difficulty and was hoping you guys might be able to pinpoint the reason I’m not able to transmit and why I get limited reception. Thank you in advance for your time and expertise!

I’ll try to be concise but want to lay this out so you’re looking at the whole picture.

Below is my setup:

Cobra 29LTD

Firestik K-8A 18 foot RG-SBA/U Coax cable w/PL-259 connectors - UPC: 716414200232

FireStik SS-274A Channel Swivel Mount w/K-4A Stud - UPC: 716414201123

Firestik II Tunable Tip Model FS4 CB Antenna 4 Foot 5/8 Wave Antenna Top Loaded - UPC: 716414110081

Wadoy SS-3H CB Antenna Spring Mount,

Squelch is all the way down until I get this figured out so there’s a lot of static so the speaker is working. Sometimes I’m hearing others conversations and then sometimes I’ll get nothing but static. Have done numerous radio checks on different days and different times yet no one responds. Whenever I key the mic, the radio goes quiet, meter goes 3/4 to the right, the antenna light stays off, and the Rx/Tx light turns from green to red . On the surface, it appears the mic is working other than no responses from radio checks (I have tried two mics on this CB).

This CB has a CAL-SWR-S/RF switch and I’ve tuned to about 1.4.

Since I thought it might be the CB, I purchased a $30.00 Uniden PRO505XL 40-Channel CB just to plug in and test. I hooked up the antenna and tried both mics and I’m still having the same issues.

I checked for grounding issues and I found something that seems inconsistent with what I have read and have seen on youtube videos. These were my results:

Tested coaxial with ohm meter and got expected results:
1. Outside to outside on each end: reading
2. Inside to inside on each end: reading
3. Inside to outside on same end, then did the same for the other end: no reading
4. Then outside on one end to inside of other end: no reading

Tested antenna install with ohm meter and got these expected results (WITHOUT coaxIal connected to CB):
5. Touch mount and stud underneath: reading
6. Touch mount and stud on top: no reading
7. Touch mount and chassis of vehicle or any grounding site on vehicle: reading
8. Touch mount and spring attached to antenna: no reading
9. Touch mount and end of antenna: no reading
10. Remove antenna and touch bottom and top of antenna: reading
11. With antenna attached touch anywhere above mount and tip of antenna: reading

Here’s something that seemed questionable. When I connect the CB, what happens is, #6, #8, and #9 changes from ‘no reading’ and I get a reading. I don’t understand this since it’s my understanding that the mount should be isolated from the antenna. Even if this is normal, I’m still not able to transmit and get very limited reception other than static on the original cb and now the extra one I purchased in order to test.

Not only is the mount securely bolted to the metal inside the hood, but I have a 12 gauge copper wire connected from the mount (not shown connected in included pic) to the end of the negative battery cable where it attaches to the metal chassis so there should be no mount grounding issues.

The antenna is attached in the below order from top to bottom:
Antenna, Spring, lug, metal lock-washer, flat metal washer (I removed flat washer because it was hitting the ground screw), plastic washer with lip that fits inside metal mount to isolate top from bottom, Mount, bottom stud, coaxial that leads to CB.

Thank you all for any advice you’re able to offer! Really want to get this thing working!

 

[jassing]

What happens if you simplify things? (get rid of spring)

 

[GFPine]

I tried eliminating that from the equation. After removing the spring and attaching the antenna directly, I connected the coaxial to both CBs and couldn't tell any difference. Thanks for the suggestion, though. Appreciate it.

 

[jassing]

are you in a position where you can take the coax & cb outside of the vehicle - the goal here would be to eliminate interference from the car & car's electrics.

How are you determining that you aren't transmitting? Receiving? I mean, w/o someone (or another rig) to respond, you may just be on a frequency all alone...

 

[mmckenna]

Not only is the mount securely bolted to the metal inside the hood, but I have a 12 gauge copper wire connected from the mount (not shown connected in included pic) to the end of the negative battery cable where it attaches to the metal chassis so there should be no mount grounding issues.

Remove this.
RF ground and DC grounding are two different things. If you are connecting directly to the battery, you may be getting some alternator noise. The mount should be grounded through the screws. If you suspect they are not grounding well enough, then you need to fix that.

From what you've described, it sounds like things are working correctly.
Mounting a CB Antenna off the side of the fender like that results in a lopsided ground plane (even if it's a 'ground independent antenna'). Ideally, you want as much ground plane under the antenna as possible. While these fender bracket mounts can work, they are less than ideal. Top/center of the vehicle roof is the ideal location. Anything other than that is a compromise.

The SWR reading suggests that you have it all connected correctly. 1.4:1 isn't bad. CB can be really hit or miss. Atmospheric conditions can play into it.

Also, you didn't mention how your power was connected. If it's not connected with the positive directly to the battery and the negative to a ground stud close to the CB, then that can be an issue. Tapping into any existing wiring, even cigarette lighter plug, can be a source of noise from the vehicle electronics.

 

[jassing]

+1 for @mmckenna.. I totally missed that you wired your antenna to the battery. You cannot "ground" your antenna to the battery - it's RF ground not voltage ground. Plus, to be effective, it needs to be a grounding strap, again, the body or frame, not the battery.

 

[GFPine]

are you in a position where you can take the coax & cb outside of the vehicle - the goal here would be to eliminate interference from the car & car's electrics.

It was tough getting the coaxial through the firewall so I can’t pull it back through the grommet. I have about 5 or 6 foot of extra cable so I might be able to hold the cb outside the vehicle. I could buy another cable of needed. BTW, I didn’t roll the extra cable up as I’ve heard that can cause problems. I’ve read it should be wrapped in a figure 8. Right now it’s just laying on the floor.


How are you determining that you aren't transmitting? Receiving? I mean, w/o someone (or another rig) to respond, you may just be on a frequency all alone...

I have been working with it on and off for a few days so I’ve done a lot of radio checks in my yard at different times and there have been instances where I’ve been on the road and have done radio checks as well so it’s not like I’ve tested it with someone else that has a cb that could tell me for certain I’m not transmitting. I’ve probably done maybe 30 checks and no one has responded even when I can hear others on the channel. I’ve mostly stayed on 19 but have scrolled through channels periodically as well.

Remove this.

Ok. I actually just added that today since I was attempting to eliminate grounding as an issue. I couldn’t tell any difference. There definitely was no improvement.

RF ground and DC grounding are two different things. If you are connecting directly to the battery, you may be getting some alternator noise. The mount should be grounded through the screws. If you suspect they are not grounding well enough, then you need to fix that.

Thanks. I have four screws through the mount but I might be able to sand underneath the mount and drill a hole for a bolt and bolt it down real tight. I’ll check tomorrow to see if I have enough access to do that. The negative cable that goes to the battery is bolted to the side of the vehicle. That bolt is where I connected the 12 gauge wire from the mount. I can remove it from there but just wanted to be clear about where it was attached.

From what you've described, it sounds like things are working correctly.
Mounting a CB Antenna off the side of the fender like that results in a lopsided ground plane (even if it's a 'ground independent antenna'). Ideally, you want as much ground plane under the antenna as possible. While these fender bracket mounts can work, they are less than ideal. Top/center of the vehicle roof is the ideal location. Anything other than that is a compromise.

That is what I’ve read but center of the roof would be a real pain for me. I occasionally use the roof rack and even when I don’t, I have a low carport I need to be able to fit under. My first choice was to put it on the rear bumper but I figured too much of the antenna would be blocked by the vehicle. My compromise was to put it on the driver’s side fender. That way, a four footer would barely fit under the carport I figured enough of the antenna would be clear enough of obstruction to get a reasonable signal. Certainly less blockage that the rear of an SUV.

The SWR reading suggests that you have it all connected correctly. 1.4:1 isn't bad. CB can be really hit or miss. Atmospheric conditions can play into it.

Also, you didn't mention how your power was connected. If it's not connected with the positive directly to the battery and the negative to a ground stud close to the CB, then that can be an issue. Tapping into any existing wiring, even cigarette lighter plug, can be a source of noise from the vehicle electronics.

The Cobra 29LTD is currently connected through the cigarette lighter and there is quite a bit of feedback from acceleration. I can even tell when a pump or something else kicks in that I wouldn't normally be able to hear. I can hear the feedback through the CB speaker. The Uniden (backup for testing) is connected directly to the battery. I haven't driven with that yet so I don't know if there's any noise from the engine or electronics. However, you mentioned the negative should be grounded close to the CB which it is not. I can change that. Thank you!

+1 for @mmckenna.. I totally missed that you wired your antenna to the battery. You cannot "ground" your antenna to the battery - it's RF ground not voltage ground. Plus, to be effective, it needs to be a grounding strap, again, the body or frame, not the battery.

The negative cable that goes to the battery is bolted to the side of the vehicle about a foot from the battery. That bolt is where I connected the 12 gauge wire from the mount. I can remove it from there but just wanted to be clear about where it was attached. Given that it's not attached to the battery and that it's only attached to where the cable bolts to the chassis, is that ok?

 

[jassing]

If you insist on adding wires to ground your antenna -- you need to use a grounding strap for RF, not a wire. I would just remove it -- if it's bolted to metal (you're mounted to bare metal, right?) just yank the extra wire.

Some areas have ZERO traffic. I was down in California & in San Francisco, I heard all kinds of chatter. Get to Half Moon Bay and there's nothing - just static. Radio checks would go unheard.

It may be working just fine; you need another person with CB to very it.
I would also wire the CB directly to the battery. Cig adapters are crap - i'd be one thing if you were using a mag mount & a temporary CB -- but since you bolted the antenna - might as well wire it correctly.

Where are you located?

Since you now have two cb's -- why not get a cheap mag mount & that way you can test transmit -- wire one to a battery in the garage, pull your rig outside, and then key up - -see if you can hear it in the garage. (use a rubber band to hold the key down & turn your radio on); then switch.

 

[WB9YBM]

Squelch is all the way down until I get this figured out so there’s a lot of static so the speaker is working. Sometimes I’m hearing others conversations and then sometimes I’ll get nothing but static. Have done numerous radio checks on different days and different times yet no one responds. Whenever I key the mic, the radio goes quiet, meter goes 3/4 to the right, the antenna light stays off, and the Rx/Tx light turns from green to red . On the surface, it appears the mic is working other than no responses from radio checks (I have tried two mics on this CB).

You didn't mention what happens to the meter reading when you talk (or whistle) into the microphone; the needle should move. If it doesn't, then somehow you're not getting audio into the radio (bad mic cartridge, mic audio line not wired properly, etc.)

 

[GFPine]

If you insist on adding wires to ground your antenna -- you need to use a grounding strap for RF, not a wire. I would just remove it -- if it's bolted to metal (you're mounted to bare metal, right?) just yank the extra wire.

Some areas have ZERO traffic. I was down in California & in San Francisco, I heard all kinds of chatter. Get to Half Moon Bay and there's nothing - just static. Radio checks would go unheard.

It may be working just fine; you need another person with CB to very it.
I would also wire the CB directly to the battery. Cig adapters are crap - i'd be one thing if you were using a mag mount & a temporary CB -- but since you bolted the antenna - might as well wire it correctly.

I just pllugged the Cobra into the cigarette lighter since it came with the adapter already attached. It was the quickest way to plug in and test it. Never intended to leave it that way. Will take the time to do a permanent install when tested and I know I'm keeping it. Bought it used so for all I know it could be damaged in some way.

Where are you located?

Since you now have two cb's -- why not get a cheap mag mount & that way you can test transmit -- wire one to a battery in the garage, pull your rig outside, and then key up - -see if you can hear it in the garage. (use a rubber band to hold the key down & turn your radio on); then switch.

Good idea. I ordered a $20 mag mount with coaxial to be delivered tomorrow. Will test then. Thanks!

 

[GFPine]

You didn't mention what happens to the meter reading when you talk (or whistle) into the microphone; the needle should move. If it doesn't, then somehow you're not getting audio into the radio (bad mic cartridge, mic audio line not wired properly, etc.)

Meter goes 3/4 to the right when mic button is depressed.

 

[FiveFilter]

Quote " I have been working with it on and off for a few days so I’ve done a lot of radio checks in my yard at different times and there have been instances where I’ve been on the road and have done radio checks as well so it’s not like I’ve tested it with someone else that has a cb that could tell me for certain I’m not transmitting. I’ve probably done maybe 30 checks and no one has responded even when I can hear others on the channel. I’ve mostly stayed on 19 but have scrolled through channels periodically as well."

A lot of effort has been expended over the years by many folks who depend on unconcerned strangers for a radio check and use the results as a guide for radio performance. It's not a very effective guide, to say the least.

 

[WB9YBM]

Meter goes 3/4 to the right when mic button is depressed.

Yeah, but does it move (wiggle) when you talk into the mic?

 

[Retroradio]

Surprised that one has mentioned that an external SWR meter could give a better indication of the SWR. The best case scenario is to borrow an Antenna Anylzer but thats an option if you know a HAM/CBer that could help you.

I have a Cobra 29LTD and of all my radios everyone likes the sound of that one best. IIRC the needle swings to the right on TX.

 

[slowmover]

Permanent mount with antenna on a quick disconnect is faster to remove or reinstall than any mag-mount.

 

[GFPine]

Just wanted to followup. I tested both CBs with a $20 mag mount hooked up to the second CB in another vehicle. Both seem to transmit and receive pretty well. I’ve also been on the interstate and they seem to work pretty well most of the time. Thanks for all your assistance.

The Cobra has the CAL-SWR-S/RF switch and I can tune it consistently to 1.4 but when I check it later, in a different location, it seems to always need retuning. Does the location make that much of a difference?

 

[mmckenna]

Does the location make that much of a difference?

Yes. Tuning your antenna is best done in a wide open area, like a big parking lot without any metal light poles around. Check the SWR with doors closed.

 

[FiveFilter]

Where the mag mount antenna is placed on the vehicle itself also makes a difference in both SWR and overall performance. The best place is in the center of the roof where it can "see" in all directions, unhindered by anything on the vehicle.

Also, the longer the antenna, the better it will communicate, all other things being equal. I like a 55-inch Wilson 500 and 62-inch Wilson 1000, both mag-mounts and capable of getting great results. A Sirio 5000 mag-mount at 79 inches is even better, but that's getting pretty tall for most vehicles.

 

[GFPine]

Where the mag mount antenna is placed on the vehicle itself also makes a difference in both SWR and overall performance. The best place is in the center of the roof where it can "see" in all directions, unhindered by anything on the vehicle.

The mag mount is just a $20 antenna I used with another CB to test the main setup but thanks for that. It makes sense that it would affect the SWR now that you mention it so I’ll keep that in mind when I set up the second CB.

Also, the longer the antenna, the better it will communicate, all other things being equal. I like a 55-inch Wilson 500 and 62-inch Wilson 1000, both mag-mounts and capable of getting great results. A Sirio 5000 mag-mount at 79 inches is even better, but that's getting pretty tall for most vehicles.

For the main setup, I have a 4’ Firestik II mounted to the driver's side fender. It can’t go on the roof so it’s either there or on the rear bumper. Can't use one any taller than 4' either.