CB radio installation in a 1998 Volvo wagon

[Sonicadventure]

The NMO saw cuts a thin strip of exterior paint, just enough to mate with the brass threaded portion of the NMO base that is just inside the O ring. You can sand and expose this small ring. Then put dielectric grease on the exposed metal and o ring before tightening down.

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What does it do, just take off enough paint to expose the metal in a slightly larger diameter? Maybe I could carefully do that with a larger size hole saw before I drill the 3/4" hole. What is the approx diameter of the surface scratch?

 

[RFI-EMI-GUY]

I wouldn't risk using a larger hole saw to replicate that. Yes it just cuts off a bit of paint so that the threaded o ring brass part makes electrical contact. You don't want the diameter larger than the o ring.

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[mmckenna]

None of the "official" NMO hole saws I have do anything to the exterior of the vehicle. Ideally the exterior paint should not be harmed in any way.
A NMO mount, installed correctly, will have an O-ring on the outer ring that will make contact with the exterior vehicle roof. There should be a small tube of grease used to lube that O-ring before installation.
The grounding of the mount happens on the underside/interior of the vehicle. The part of the mount with the coax attached will have some teeth to it that will make good contact with the underside of the roof when you tighten it all down.
That shouldn't need anything at all. If the O-ring is installed and properly lubed, there shouldn't be any way for water to get inside.

You don't need a loop under the antenna, although leaving a bit of slack can be helpful. Any excess coaxial cable should be routed to the radio area and cut to length. If you are using a pre-installed connector, just route the cable in such a way to use up the excess cable. Leave a bit of slack behind the radio so you can easily remove it, or re-terminate it, if necessary.

I've never needed a coaxial cable choke on any of my mobile installs.

 

[RFI-EMI-GUY]

https://fccid.io/document.php?id=1470598

See page 35 for instructions for NMO mounting and special hole saw useage. Ripley makes a hole saw for this purpose. It scores the perimeter of the hole for grounding.

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[RFI-EMI-GUY]

See description regarding scoring paint for grounding.

http://www.ripley-tools.com/products/hsk


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[Rred]

A little silicon grease over any bare metal will prevent rusting and allow a proper and secure electrical connection, whether that is RF or ground. Cheap insurance when there's any question of preventing corrosion.

 

[Sonicadventure]

So I got everything hooked up, but no antenna and no mic hooked up yet. About to take it out to an open area so I can tune the antenna. One thing that seems off to me is that when I turn the radio on, there is almost no noise unless the volume is all the way up. It seems very muted. I seem to remember it making more background noise when I had it plugged into the cigarette adaptor. I don't know maybe the minimal noise is desirable, but before I hook up the mic and the antenna I wanted to get some feedback on this thanks.

 

[RFI-EMI-GUY]

Does that model have an RF gain control? Is the squelch wide open? Is the speaker covered? Do you have 12V to the radio?

Unlike FM receivers AM radios usually need an antenna to generate much background noise. So try hooking it up tuned or not.

But first, check the antenna assembly with an ohmeter. With it disconnected from the radio, you should have infinite resistance from center PL259 connector pin to shield. You should have nearly zero resistance from the center pin of the NMO base to the center pin of the connector. Likewise zero resistance from the shield of the connector to the NMO base, and zero from the vehicle frame to the NMO base. Anything greater than an ohm, might indicate a problem.

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[Sonicadventure]

Ok so, I went ahead and mounted the antenna and gave it a shot. Not a lot of CB activity in my immediate area but I got a good radio check on 19 from a trucker who was about 3-4 miles from and he said I was hitting him with 5 and sounded fine. After driving for awhile, I stopped and scanned the channels and found some guy talking incessantly on channel 6, and also several people talking on channel 27. Just installing the antenna made a huge difference in the amount of sound from the radio.

Unfortunately, the vintage 23-136 Midland SWR meter I bought on eBay seems to be broken. When I put it inline, I couldn't get the "Power" needle to move at all, and even with playing with the adjustment knob on the meter I was maxing out the SWR scale (4) when the power dial was anywhere past 1.

So, I disconnected the antenna and put it away and disconnected the mic. Although it seems to be working fine, I don't want to compromise all the work I did until I can get a functional SWR meter. Anyone have luck with those $30 Workman dual readout meters? That seems to be a popular one on eBay at the moment.

 

[RFI-EMI-GUY]

Ok so, I went ahead and mounted the antenna and gave it a shot. Not a lot of CB activity in my immediate area but I got a good radio check on 19 from a trucker who was about 3-4 miles from and he said I was hitting him with 5 and sounded fine. After driving for awhile, I stopped and scanned the channels and found some guy talking incessantly on channel 6, and also several people talking on channel 27. Just installing the antenna made a huge difference in the amount of sound from the radio.

Unfortunately, the vintage 23-136 Midland SWR meter I bought on eBay seems to be broken. When I put it inline, I couldn't get the "Power" needle to move at all, and even with playing with the adjustment knob on the meter I was maxing out the SWR scale (4) when the power dial was anywhere past 1.

So, I disconnected the antenna and put it away and disconnected the mic. Although it seems to be working fine, I don't want to compromise all the work I did until I can get a functional SWR meter. Anyone have luck with those $30 Workman dual readout meters? That seems to be a popular one on eBay at the moment.

Are you sure you don't have the input and output of the meter reversed?

Those meters have two diodes inside, one for forward the other for reverse. I had one of those and can tell you from experience if some ham had it and applied power from a 70 centimeter (440 MHz) mobile rig, the diode in the power side will blow. It is for 27 MHz and below only, maybe to 150 MHz. It is a great meter and easy to fix.



http://ki3u.byethost3.com/Radio-Phy...versing the Midland 23-136 SWR Meter.html?i=1

 

[Sonicadventure]

Are you sure you don't have the input and output of the meter reversed?

Those meters have two diodes inside, one for forward the other for reverse. I had one of those and can tell you from experience if some ham had it and applied power from a 2 meter (144 MHz) mobile rig, the diode in the power side will blow. It is for 27 MHz and below only. It is a great meter and easy to fix.



http://ki3u.byethost3.com/Radio-Phy...versing the Midland 23-136 SWR Meter.html?i=1

I will have to open it up and see. The one I have is in very good shape, almost looks never used. It is clearly marked "transmitter" and "antenna" on either side and I'm positive that I hooked it up correctly. Nothing from the power dial though. No movement. Will the blown diode be easy to spot?

 

[RFI-EMI-GUY]

I will have to open it up and see. The one I have is in very good shape, almost looks never used. It is clearly marked "transmitter" and "antenna" on either side and I'm positive that I hooked it up correctly. Nothing from the power dial though. No movement. Will the blown diode be easy to spot?

After some searching I found the manual and schematic for that meter.

If you test the diodes, use a ohmmeter that has a very low voltage between the leads. These are common 1N34 germanium diodes. You might have to shop a bit to find exact replacements. If you use some different diodes, replace them as a pair.

The power side might have a blown diode or the meter movement is sticky.

It is symmetrical. meter so, in theory, in a pinch, you could place it in line so that forward power is measured on the VSWR scale and set the knob for full scale, then reverse it and read the VSWR. If the meter reads greater than full scale after reversing, set knob back to full scale and reverse the connectors and read again the VSWR.

Of course, you need to get this sorted out before you start cutting the antenna rod. Because you cannot cut it "too long"

https://drive.google.com/file/d/0B7yahi4JC3juanNvaURJX1FKSnM/view

 

[Rred]

Checking the diodes is a good solution, replacing them should be cheap enough.

But if you want to do something faster, look for a decent new swr meter from any ham or cb shop online. I took a fast look at R&L, R&L Electronics and found
"PDC-5 ASTATIC PDC5
[PDC5]
$33.95
SWR/POWER METER 27MHz 10/100W"

and R&L is competitive with most of the bigger radio shops, who should have similar gear available. At that price, brand new from a reputable vendor, you don't have much to lose. You can always sell one if you fix the other.

 

[RFI-EMI-GUY]

Checking the diodes is a good solution, replacing them should be cheap enough.

But if you want to do something faster, look for a decent new swr meter from any ham or cb shop online. I took a fast look at R&L, R&L Electronics and found
"PDC-5 ASTATIC PDC5
[PDC5]
$33.95
SWR/POWER METER 27MHz 10/100W"

and R&L is competitive with most of the bigger radio shops, who should have similar gear available. At that price, brand new from a reputable vendor, you don't have much to lose. You can always sell one if you fix the other.

Comments; I used to own a Midland 23-136 meter exactly like Sonicadventure. I kind of liked the dual meter approach because you could watch power out and VSWR at same time. I got "fancy", started doing a lot of high power UHF work, so I got a Bird wattmeter , traded off the Midland. Looking back the Midland was pretty nice and well made CB accessory. The Bird is clunky, not something you would leave in line.

The Astatic PDC-5 has gotten mixed reviews regarding the built in tuner. Apparently the mechanism comes apart inside.

Also Sonicadventure take note: When tuning the antenna rod of your new NMO antenna, don't use the matcher feature of the PDC-5. It should be switched off. In fact the NMO antenna tuned to a center channel of the CB band should require no external tuner.

The Midland can be repaired for a few dollars. Radio Shack still sells germanium diodes.
https://www.radioshack.com/products/nte-1n34a-germanium-diode

as do others:

https://www.mikeselectronicparts.com/product/1n34a/

I would buy some spares as they are cheap.

The only other parts that can fail in the meter are the meter movement itself and the potentiomenter . It would be easy enough to troubleshoot by soldering a silicon diode like a 1N4148 in to test. But for repair, I would use the 1N34A as original.

 

[Sonicadventure]

Well after months of work and research I finally achieved my goal of having a CB in my Volvo. I really appreciate all the help I got from this forum.

I removed the passenger knee bolster, installed the map pocket from a 2000 XC70, and installed the radio in the map pocket. Went with the 3/4" NMO mount placed square in the middle of my non sunroof roof.

Power came via the 30 hot wire in the accsseory jack. Soldered a two-pin trailer quick disconnect to the radio wiring and then soldered a Volvo OEM wire tip on the power lead and actually used the accessory plug as is. Ran the power wire under the drivers side carpet just near the steering column and then through the pass-through area above the heater core. For a ground, I soldered a ring connector and used one of the bolts that formerly held the knee bolster on as a ground lug. Both the coax and the power wires were run through a 3/4" hold in the front left corner of the map pocket. There is just enough space up there above the passenger side entry light for everything to fit neatly with no stress on the wires. Coax was run up the passenger side trim to the NMO mount. I did have to use a utility knife to remove a section of that black sound damper stuff that was glue to the roof to properly install the NMO base but that wasn't too bad.

The radio is a little further away than I would like, but it's solid and secure. I used a piece of aluminum bar stock as a reinforcement for the CB mount bolts. I also drilled two little holes in the map pocket top and ran a zip tie through them and attached it to the glove box support member to give the whole assembly a little more strength.

The radio I used is the ubiquitous Uniden Pro510XL, which is a simple, sturdy and relatively light unit. I bought it used on eBay for $17. So far it works great. For the antenna, I got a Larsen NMO27B. It really gets out there. The main reason I went with this set up is because I have a low parking garage and I have to remove it before entering. When it's not in use, I have a little rain cap to cover the mount.

There isn't much CB traffic in my area, but I've had some good contacts. People have confirmed that I'm getting out there pretty good. It's a fun hobby that I've had a lifelong interest in and I'm looking forward to getting some good use of this. Thanks everyone for your feedback. I'm going to post some photos of the installation for reference.

 

[Sonicadventure]

The finished product

 

[RFI-EMI-GUY]

Nice install! Is that an AWD wagon? How is the reliability?

 

[Sonicadventure]

Nice install! Is that an AWD wagon? How is the reliability?

Thanks! It's a 1998 base mode, non turbo not awd.

In general Volvos are well built cars, but most people say avoid the 2001-2003 model years across all models because that was when Ford bought them and revamp a lot of things. Not sure when Ford got out of the deal, but I heard the 2006 and later Volvos are again very reliable. The 93-2000 models both the 850 and S & V 70 series in general are known to be very reliable. However they are very prone to serious engine damage if the timing belts break as they are all DOHC interference engines. You really have to do the timing belts at the proper intervals. It's not an easy job, but it is doable with fairly simple tools and DIY vids on YouTube. You also have to make sure they don't overheat because head gasket failure usually results. Have to use the correct coolant.

But in general they are engineered for high mileage. Mine has 243,000 miles on it and it still runs strong. I know people who have these cars with 350k+ on the original engine with just routine maintenance as mentioned above.

 

[mmckenna]

Very nice job. Glad to hear it's working for you.

 

[RFI-EMI-GUY]

Thanks! It's a 1998 base mode, non turbo not awd.

In general Volvos are well built cars, but most people say avoid the 2001-2003 model years across all models because that was when Ford bought them and revamp a lot of things. Not sure when Ford got out of the deal, but I heard the 2006 and later Volvos are again very reliable. The 93-2000 models both the 850 and S & V 70 series in general are known to be very reliable. However they are very prone to serious engine damage if the timing belts break as they are all DOHC interference engines. You really have to do the timing belts at the proper intervals. It's not an easy job, but it is doable with fairly simple tools and DIY vids on YouTube. You also have to make sure they don't overheat because head gasket failure usually results. Have to use the correct coolant.

But in general they are engineered for high mileage. Mine has 243,000 miles on it and it still runs strong. I know people who have these cars with 350k+ on the original engine with just routine maintenance as mentioned above.

I guess if you buy one that is running well it is a good indication the timing belt never failed during previous ownership.

Yeah I also remember Ford buying into Jaguar as well as Volvo. I was parked next to one of those Jaguars and it looked an awful lot like the Ford Taurus I had at one time. Must have driven the engineers crazy being forced to shoehorn stuff from the Ford parts bin into existing model line up.

The Chinese own Volvo as of 2010, and Tata of India now owns Jaguar and Land Rover.