I know, i know. Another CB radio question.

[robustbambi]

I just installed my new cobra 29 NW classic CB with a 4 ft firestik II antenna and I'm not getting any power to the radio when turned on and plugged in.

BACKGROUND INFO:
Antenna is mounted in back like so...






The 18ft coax running to the center console underneath the carpet along the doors.




I lengthened (heat wrapped) the positive and negative wires (I'm checking the connections to ensure a good current tomorrow). Then I shoved them under the driver seat and up under the foot pedals so I could bring them up to the fuse box. I grounded the negative on the bolt right next to all the fuses (white wire) and then stuck the red positive wire into the cig fuse so that it wont run the battery down while the truck is off.




I plugged in the radio and nothing, it won't turn on.
I'm pretty confident I did everything correctly, but I'm not the best electrician/ mechanic.
Does anyone think they can help determine the problem???

 

[TRAIL TAILOR]

Robust, check all fuses first. Do you have a good ground? Looks like its good, but it looks like that's painted metal under the bolt. You might try scratching it off some if it is. Check all wiring again. You possibly might have a bad radio, unfortunately it happens from time to time.

J

 

[Kofoed]

Ground might be no good

 

[robustbambi]

ill sand down the paint for the grounding some and check the wires tomorrow. hopefully thats the problem, and not a problem with the radio itself.
thanks for the replies

 

[george_tlc]

'tis called a multimeter - if you don't have one, BUY one. Measure that you have 12V at BOTH ends of your wiring to the cr@p band radio.

Those wires you used look mighty thin. For the ground, at least use a ring terminal and crimp the wire into it. Looks too much like a hack job right now...

cheers,
george.

 

[sdnative]

'tis called a multimeter - if you don't have one, BUY one. Measure that you have 12V at BOTH ends of your wiring

x2. Also check continuity between the your ground connection and the negative battery terminal.



I wouldn't use a 15A fuse for a 4W load (CB). You only need a 1A fuse. Try to use a always hot source (preferably run it all the way to the battery) and use an inline fuse holder or something.

 

[robustbambi]

Rewired it, as to not look like a hack job, directly to the battery with 16 gauge wire and grounded on an unpainted frame bolt under the hood.
Now, everything's working well!!!
I just need to ground the antenna wire a little better and it will sound crystal clear.

 

[george_tlc]

Great you have it working. Wiring things properly is a good idea, otherwise hacks build on hacks...

I presume you have fuses right near the battery for your new wires...

cheers,
george.

 

[robustbambi]

Doesn't the cb radio's positive cable have a fuse on it? I'll go unplug this thing right now just in case. I'd hate to destroy te radio :0
(you can see how bad I am with electrical equipment)

Just went and yes the wire already has a fuse on it. Would y'all recommend another nearer to the battery?

 

[george_tlc]

Doesn't the cb radio's positive cable have a fuse on it? I'll go unplug this thing right now just in case. I'd hate to destroy te radio :0
(you can see how bad I am with electrical equipment)

Just went and yes the wire already has a fuse on it. Would y'all recommend another nearer to the battery?

The KEY is to have a fuse at the battery, because if the wire from the battery all the way to your radio fuse rubs against the body and shorts, the fuse at the radio end will NOT protect the wire from melting....

There's a reason the factory has FUSIBLE LINKS at the battery - so if something in the harness shorts the fusible link will save the harness. The fuses in the harness will protect the downstream devices.

The idea of the fuse in this case is to prevent a wiring short that could melt/catch fire/burn car to the ground.... Since you have wired directly to the battery (which is a good thing) you NEED to have a fuse at the battery to protect that wire...

cheers,
george.

 

[robustbambi]

Ok thanks, that makes sense.
So I'm looking for an inline fuse holder as stated above?

 

[george_tlc]

Yeah, add an inline fuseholder in the battery tray. You can pick up fuse holders that use the same style blade fuses as the rest of your cruiser at most autoparts stores. Stick a 7.5A fuse in it - more than enough for the task at hand.

cheers,
george.

 

[robustbambi]

Yeah, add an inline fuseholder in the battery tray. You can pick up fuse holders that use the same style blade fuses as the rest of your cruiser at most autoparts stores. Stick a 7.5A fuse in it - more than enough for the task at hand.

cheers,
george.

Alright man, That'll be my little project for tomorrow. Thanks a lot for all the information.
Its helped a ton!

 

[sdnative]

Glad you got it working.

I take back what I said above. After reading the manual, it looks like these CBs can draw just over 2A so my 1A fuse recommendation above probably wouldn't be enough. I knew I was using 1A fuses, but it is for my APRS TNC, not the CB as I had thought. So any fuse between 5A and 10A should work fine.

 

[robustbambi]

Glad you got it working.

I take back what I said above. After reading the manual, it looks like these CBs can draw just over 2A so my 1A fuse recommendation above probably wouldn't be enough. I knew I was using 1A fuses, but it is for my APRS TNC, not the CB as I had thought. So any fuse between 5A and 10A should work fine.

No problem, I have a "spare" 7.5 in the fuse box I'll use. And just to make sure, I'm looking for this sort of fuse holder...




Thanks

 

[sdnative]

That will work just fine. You can also find the weatherproof style which is what I prefer.

Get one that uses ATO/ATC fuses so you can standardize on one type.

 

[robustbambi]

Thanks for all the help guys, if I manage to screw up my antenna's grounding plane, I'll be sure to ask here so you can throw some more knowledge at the huge noob

 

[robustbambi]

As I suspected, I can't get the ground plane just right. I don't want to move the antenna anywhere, like the roof or anything. My swr meter was reading about 1.6-2.0 and that's pretty bad, but better than what is going on right now (radio is not even showing that te antenna is attached).

In the first picture, I show the mount attached to the D-pillar, is there a better way to ground by attaching wire to the mount and then wiring it to the frame? Or should I sand down te paint underneath the mount?

 

[sdnative]

As I suspected, I can't get the ground plane just right. I don't want to move the antenna anywhere, like the roof or anything. My swr meter was reading about 1.6-2.0 and that's pretty bad, but better than what is going on right now (radio is not even showing that te antenna is attached).

A SWR of 1.6-2.0 is more than acceptable. What do you mean the radio is not showing an antenna is attached? Does the radio have a built in meter or are you using an external?

First off, you're not going to get very good performance mounting the antenna where you did. Very inefficient. If you're getting under 2.0 SWR I would count my blessings and move on.

You are dealing with two types of grounds here: electrical ground and RF ground. You aren't going to have good RF ground due to the lack of a ground plane (counterpoise). Best place is on the center of your roof, using a mag mount for example.

You can get good electrical grounding by making sure you have a good path back to the battery. Make sure all connections are to bare metal (sand down if necessary). Get out your multimeter and check resistance between the mount and the negative battery terminal. Should be less than an ohm or close to it. If not, start chasing down higher resistance connections and deal with them.

 

[robustbambi]

The electrical ground is good, connected to an unpainted frame bolt under the hood. And I've got the + wire with the weatherproof ATC fuse connected to the battery. I'm getting plenty of power to the console. All is good there.

Now I'm working on grounding the antenna.
the antenna warning light was on, it has sense turned off after sanding down underneath the antenna mount. The radio has a built in SWR meter, but i am also using another one from a friend because i read on here that the on board SWR isn't that good for the initial setup.