Antenna for Midland CB

How'd you check out the coax?
If that Volvo has the Rami multiplexor, it is important to note that you CANNOT check for DC continuity from the CB radio connector to the CB antenna coax. The Rami doesn't pass DC, although it does pass RF. An MFJ antenna analyzer will show if it has failed or not as regards antenna tuning, but nothing you can do with a voltmeter or ohmmeter will.

Their troubleshooting manual shows doing DC checks to the be-bop radio connector, where a failure means it's failed, but a pass doesn't necessarily mean the CB antenna line is OK.

As Rat noted, the stock Volvo antenna network is OK for an unmodified CB, but if you're going to run any more than stock (legal) power, you'll need a separate coax and antenna or risk blowing out the multiplexor.

Hope that helps,
-- Handlebar --

 

I still haven't seen a Volvo in at our shop; I should cruise out to one of the truck stops nearby and take a look. If the roof in the Volvos is fiberglass, then the antenna they equip on them is special. If that's the case, you won't be able to swap with a "standard" CB antenna that's made to work against a ground plane and get great performance.
I'll research a little further in the next couple of days. But unless someone has already blown the Rami unit out, you may find you do all right with that Midland and the stuff that comes on the truck. Rami actually makes some very high-spec equipment, including military application antennas and such. Their site has troubleshooting guides for their truck kits.
And kudos for not wanting to garbage-up your radio. The radios I have installed in the van and base are all stock, and do just fine. It's actually their nice sound that drives some of my customers in to the shop, as I am careful never to advertise on the air. The Charlotte field office is too close to risk teasing them with violations.
-- Handlebar --

 

About all you can do is check the coax itself from end to end and hope the multiplexor is doing its job correctly. You will know if it is not because your recieve and transmit won't be worth a darn.

Oh and Peterbuilt has the same setup as Volvo. Well my 04 379 does anyway.

 

Rat,
OK, yup, you're right at that. If it clearly isn't working with a radio that you know *is* working, then it's something downstream from the PL-259 going to the Rami box.
I was looking at their website -- which is where I found their troubleshooting guides -- and was interested to see they've got specific units for the different brands of trucks, all made to work as a unit. But all still susceptible to the same problems of too much power from the CB radio.
Seems like a good idea at first, until it doesn't
-- Handlebar --

 

Hey Rat, isn't the door and the cab itself on a Volvo steel? I think that's part of why they're so heavy. I think just the roof itself is fiberglass.

 

Midroofs and condos are plastic/fiberglass, Flattops are steel. No there is nothing special about the Volvo antennas. They are just a peice of fiberglass with a single wire that wraps around it and have the same failure problem as all fiberglass type antennas. That is the wire is soldered to the base and it breaks off. They can be repaired if you have the skills. I repair them by silver soldering them. It requires a higher heat to melt the silver solder (Harris Safety Silv 56) which is why I use a mapp/oxy setup

 

Rat,
Cool; thanks for that info. It's *possible* that that antenna is made to work with no ground plane, and the piece of coax from the Rami box to it may be part of the matching network. Generally, those suck (to use the technical term) compared to nearly any antenna over a decent ground plane.
I've sent off a question to the engineers at Rami about what their matching network is doing, since they're not very forthcoming in their public info about the system usually. Maybe they'll let me in on some data, cuz it's likely I'll be trying to maintain their systems in the field at some point.
If/when I hear back from them, I'll update the thread, or start a new one with a name like Volvo Antenna Info or sumpin' logical.
Thanks again,
-- Handlebar --