Installing CB in '08 Peterbuilt - Diesel Forum

Bret_B · 02-13-2008, 08:02 PM

Have a question about installing a CB in the new company truck. It is an '08 Peterbuilt, and it is pre-wired for a CB and has twin antenna's. The factory wires in the cab have an actual plug/socket (female). The new CB doesn't have a plug/socket, just the leads. The question is, do I just cut the plug off the factory wires and butt-connect the wires, or should I try and find the correct male plug and make it "right"?

Also, the CB being installed is a Uniden 520pro (I think that is what the box said). The directions said the SWR shouldn't be more than a reading of 2.1. What the heck is that, and how important is this? There is no dial or gauge on the CB, or is there something missing. Yes, it is a new, in box, CB. I installed a Uniden 510 in my personal truck, turned it on, and everything worked fine. Another driver told me I could blow out the antenna's and/or CB itself without the right reading.

Thanks guys, I could use the insight and education.

Bret

Kartek · 02-13-2008, 09:09 PM

Hi Bret,

Have you looked in the glove box and other compartments for the opposite end of that connector? I know Ford puts the brake controller pigtail in the glove box and I thought Pete might do something similar. I would also double check the voltage on that lead and make sure it's not 24v. I wired a Greyhound type bus for video and blew up a VCR because I didn't realize it was on 24v.

If you find the connector, simply splice it onto the CB's harness. Otherwise, I would pick up a matched pair of connectors from Pep Boys or Radio Shack and splice them in so you can remove the CB easily if need be. On a nice new truck like that, I would do it that way.

As for the SWR, that stands for standing wave ratio and it has to do with tuning the length of the antenna and transmission effeciency. You will need an SWR meter to adjust it since your CB is not so equipped. The meter simply inserts inline with the antenna and is removed after adjustments are made. You can probably buy one from RS and they aren't expensive.

To adjust SWR, hook it all up and set the CB to channel 20 or someting in the middle of the range. Make sure no one is holding or standing near the antennas as a body will throw off the reading. Set the cal switch on the meter to CAL and key the mic. While holding the key, adjust the meter until it reads right at the calibration mark. Release the key and flip the meter switch to SWR or whatever is the other setting. Key the mic again and note the reading. If it's out of spec, look at your antennas and there should be a smal hex set screw at the bottom thats holding the whip to the base. Loosen that screw and pull the antenna out a bit, re-tighten and re-key to check SWR again. If the number goes up, then move it back the other way. If it goes down, loosen the screw and move it a little more the same way . Keep repeating this till you find the sweet spot where the SWR is at a minimum. This will give you maximum performance from the rig.

Also, it should be noted that in addition to keeping people away from the antennas when testing, the antennas should also be mounted in their final positions and the truck a good distance away from buildings and other trucks for the most accurate adjustment.

All this should be in the SWR meter manual too. Hope it helps!

Band_Member · 02-14-2008, 08:29 AM

Kartek, Good description of tuning the antennas for SWR. I might add that sometimes the stainless steel antenna whip is too long as it was in my case. I had to trim about 1/2 inch off then I could find the sweet spot. To trim I just scored the base end of the s/s whip with a file 1/2" up from the end and snapped the piece off with a pair of pliers.

The Uniden 520 pro is a nice little radio too. I've owned 2 of them of which one of them I fried when my 12VDC power supply lost its regulator and put about 22 volts on it.

Kartek · 02-14-2008, 10:01 AM

Thanks Band Mem,

It's been a long time since I messed with this stuff. Just a couple other notes:

Since you're using twin co-phased antennas, you'll have to do them both at once. Loosen both set screws and shorten them both all the way before taking a reading. After each reading, move them both out about 1/16" until the optimum reading is achieved. If the SWR goes up immediately after you move them the first MCH then, you'll have to cut a bit off the whip to shorten it up.

Also, you may be dealing with fiberglass whips and some of them may not have adjustment screws and you're stuck with them the way they are.

Finally, for best performance, mount the antennas straight up rather than tilted forward. I guess it's suposed to be stylish or something to do that but they're designed to be perpendicular to the ground. I think they're also supposed to be exactly 8' apart from one another but I may be geeking out too much...

VCRacing · 02-14-2008, 02:30 PM

IIRC co-phased antennas need to be around 9' apart for optimum performace, as recommended by Firestik.
I would recommend running a single coax to one side and run a live antenna and a dummy antenna if you want the dual antenna look. As far as tipping the antennas forward, i use Wilson 2000's and they are tipped forward , as i travel down the hwy the wind resistance will cause the antenna whip to flair back to a vertical postion. I know its a PIA to run a single coax but they're easier to tune and maintain.

Bret_B · 02-14-2008, 04:08 PM

Thanks guys for the responses.

I looked through the truck and didn't find a male plug anywhere. I did however re-find the bag of fuses that was taped to the inside the fuse panel.

The antenna's are factory wired and are one on each mirror. Don't know the exact distance, but there is plenty of distance.

From what I gather from others who have found this or a similar plug, they have just cut it off. Apparently, manufactures have their own accessories, and a CB wiring attachment/CB kit is one of them. This is what I was told, I don't know for sure if that is actually true.

So, tomorrow, I'll finish the install with bullet connectors and heat shrink. I'm stopping by a Radio Shack to see about an SWR meter. Hopefully it won't be to expensive.

I'm still having a hard time bringing myself to put screw holes for the mount bracket in the access panel. Can't really explain what it is, or why for me it is a problem, but you'd think there would be a bracket or holes already in place because it is so common for a CB to be installed. In the Mack I just got out of, there was a mount and push-close type power leads on the dash, out of the line of sight.

Thanks guys, I'll let you know how it all turns out.

Bret

Kartek · 02-14-2008, 06:51 PM

Looks like you have it under control. Look at the antennas to make sure they're adjustable before you go spend $50 on the meter. I think some of them are fixed length. If you decide to buy the meter, don't forget to get a small length of antenna wire to connect it inline with the CB.

Bret_B · 02-20-2008, 04:25 PM

Well the CB is in and I was able to use an SWR meter from one of our maintenance guys who just happen to have one at home. For the installation, I just cut the plug end off the factory pigtail, connected the wires, put self tapping screws in for the mount bracket, and tightened up everything. Took about 20 minutes, but days of getting through cutting the plug off and putting holes in the access panel. Looks decent and is functional.

The only dilema I have now is getting the antenna's tuned. On channels 18-21, the meter reads about 1.5 after calibration. Move down to channel 1-3 and the meter reads .7. Move up to channel 40 and the meter reads 2.1~2.3. One of the other drivers said that is way to much of a swing. Not to mention, I couldn't hear him outside of about a mile. So for the rest of the week, we'll be toying with this set up.

As for the antenna mounts, there are no jam nuts, or adjustment at the base. It appears I will have to remove the antenna, remove a cap, and snip a coiled wire down. Not sure yet, just didn't get that far today between loads.

Thanks again guys. I'll probably start another thread for tuning if need be.

Bret

Band_Member · 02-20-2008, 06:15 PM

The SWR is for transmitting. As mentioned in an earlier post you tune the SWR with the radio on channel 20 which is mid band. You will have a variation on each end. How much I guess depends on how close you can get it to 1:1 on channel 20.

Having two antennas make it a bit more tricky too.

The tuning of the antenna(s) will not affect reception. In most cases you can get reception with just a piece of wire. So the fact that you cannot hear him beyond a mile is because of something else (i.e.; interference, his rig, etc.).