Having seen it all reassembled, I'm rather wishing I had gone with 1.2k or 1.5k for the resistor, to dim the light a little more. But if it's a real problem in the car I can always put it back on the bench and do it again.

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I have a CB radio in the car, a radio I've owned forever. But it's got just the right balance of features and not-too-fancy that I always end up using it if I try anything else. Well, the car went in for service the other week and I took it and the amateur radio control head out because I thought they might have to pull the center console for troubleshooting. They didn't, but the radio has been sitting on the floor in here for about a week now. And I was reminded that the back light for the RF/SWR meter has been burnt out for ... probably longer than it's worked, at this point. (Yeah, I've had this radio a while.)

So after some disassembly I determined it was using a small 12v incandescent bulb, as I suspected. The filament long gone. Thankfully the bulb was mounted in a little silicone insert/diffuser making it really easy to remove from the meter in the radio. I acquired some 3mm warm-white LEDs, and with the help of a 1k resistor, replaced the burnt out bulb.

Knowing that I'd probably not have any spoons free when the new GPS receiver arrived, I went ahead and found the pinouts for it (it uses a mini-din 6 connector) and made up an adapter to connect it to the existing DE-9 adapter that plugs into the radio. It needed a +5v power source, so I just cut the old power adapter off the dead Garmin and wired it in.

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Well, some fool* dismantled the interior of the entire rear half of my car. So I guess I get to go put that back together now.

*Me. I am that fool.

Once the antennas were reinstalled, I hooked the NanoVNA to the CB antenna and swept it. It wasn't quite centered perfectly on channel 19, but it was close enough. The best SWR was around 1.3:1. Re-connecting the radio and calibrating it's internal SWR meter showed that for channel 19 it was about 1.5:1. Much better than the 3:1 or 4:1 I was seeing before.

I did notice when I swept it, that I would have better SWR on the higher frequency channels than the lower. If I ever get involved in a real conversation I'll have to keep that in mind. But I mostly use it to listen to what's going on on the road.

I did not sweep the 2M/440 antenna, as it terminated in the trunk and both antennas were also mounted on the trunk lid. I would have had to fold both back seats down, and at the moment the bottom seat cushion for the back seat still needs to be reinstalled from the whole GPS debacle.

Overall I am happy with where things are now. Just waiting for the new GPS receiver to arrive.

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Having success there, and a desire to avoid further contortionist acts that anything on the interior of a car requires, I moved on to the antennas.

Simply removing the antennas caused one of the NMO mounts to come apart. I'm pretty sure when Dad has removed and reinstalled the antennas in the past, he's over-tightened the antennas, which will lead to this.

Once I had everything apart, I cleaned the trunk lid around the antennas thoroughly. I put rain caps on them when I visit the car wash, and they cover an area around the mounts as well.

Having done all that, I carefully reassembled the mounts. I lack the fancy tool to keep the center of an NMO mount from spinning when tightening the outer nut, but I've found that a pair of tiny needle-nose pliers works wonders. Especially the curved kind. I cranked down on the nut on each mount as much as I dared, without crushing the integrated washer and grinding it into the trunk lid. Hopefully they wont come lose again.

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Both speakers are fixed for the amateur radio in the car. Initial fiddling found that one worked if I jiggled with the cables. The one that didn't ... I had a flawed testing methodology, so it very well may have.

Both speakers used a short custom 3.5mm mono to RCA adapter that I had made, and both were made with some really nasty looking audio cable I salvaged from who knows what. The kind that's hard to solder because it's half plastic on the inside.

So I just outright replaced them. New wire (just some zip cord, it's not like noise is an issue) and new connectors. I also took care to not overheat the 3.5mm connectors when soldering them, as that has a tendency to make them go intermittent (they were cheap, and the plastic insulating the various conductors isn't as heat resistant as it should be IMO).

Everything seemed to be fine with the new adapters. Especially once I figured out that the "A" transceiver needed to switch to a mode without RX PL to unsquelch 🤦‍♂️

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Just looking at the old install photos from my car, before I go try to figure out what's up with the speakers for the 2-meter rig.

Apparently I used a different model speaker under each seat 🤦‍♂️

No clue why. Probably something to do with the one I wanted to use not fitting under the passenger seat. Still, irritating.

The empty shelf held the power supply, and another scanner. The purpose of the second scanner eludes me at the moment. I may have been experimenting with recording certain talkgroups on the trunked system? I have a vague memory of that.

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I just unearthed this photo. Sadly I'm not in the radio world anymore, so it sits in the shed, forgotten these days.

Left to right, top to bottom:

* Stereo, for audio from the computer in the room.
* The empty hole is for a Uniden BCT-8 scanner, driving Trunk-88 on the PC. It decoded the control channel of the local trunked radio system and let me keep an eye on it. I was one of the main techs that supported that system, so I found it a useful tool
* Motorola Astro Spectra with W9 control head, 800Mhz. Used for monitoring/testing the Type II/SmartZone systems we supported in the area
* Motorola XTL-5000 with W9 control head, 800Mhz, Used for monitoring/testing the P25 systems we supported in the area. Super handy for asking "Is it up?" of the one that was far away and the users were less than helpful
* Radio Shack HTX-10 10-meter AM/SSB/FM, having nothing more advanced than my tech ticket, 10M was the only HF band I could do voice on (IIRC)
* Yaesu FT-7900R 2M/440 transceiver

@vfrmedia Yeah, it's suspended under the "package shelf" (or rear dash, or whatever it's called). Up out of the way where most things in the trunk wont touch it. The fuse block I added is located there too, as I had the radio and GPS receiver to power. I feel like there was a third item but I can't remember what it is.

I have a circuit breaker connected directly to the battery, and then a pair of heavy gauge wire running to the fuse block/distribution in the trunk.

I still need to find a source of switched ignition and run it back there to drive a relay, but I've gotten good about turning the radio off when I'm done with it.

@vfrmedia Not sure where the photo of the install with the CB went. Oh well.


I've got a mid-size sedan (by US standards), so it wasn't too much trouble to fit the control head for the radio on a flexible tablet mount in the front. It bolts to the floor using one of the seat bolts on the passenger side. The CB uses an upside-down pegboard drill holder and it's original bracket to suspend itself from passenger side of the center console.

I'll have to see if I can find photos. I'm sure I've gone some.

@vfrmedia Yeah, cars gone by I learned the magmount lesson. But the paint was already toast anyway.

I've gone through a number of different mounts on different vehicles over the years. I've had several custom CB mounts that either used existing holes or were mounted in places where holes wouldn't be noticed. For the longest time I just had CB and scanner, and I used a trunk-lip NMO mount for the scanner.

Before I was unable to work any longer I was a two-way radio field tech. I was already passingly familiar with NMO, but working there it was everywhere. And we had tons of the stuff. So when I was looking for a permanent antenna mount, that was what I reached for.

I did finance the car, and I didn't check to see what they thought about two 3/4" holes in the trunk lid. I just did it. But it's since been paid off.

@vfrmedia It's probably more like they rattled loose. They're NMO mounts (if you're familiar). They just sort of screw together and clamp around both sides of a hole. Every so often when I go to take the antennas off I find that the mount has come loose enough that I'm unscrewing the two halves instead of the antenna off the mount. I suspect part of this is that I'm not the only one who takes them on and off, and the other party over-tightens the antennas.

They both need to come off, everything get cleaned, and I need to decide if I'm going to try and remove a little paint on the inside where the bottom of the mount braces itself. It'd get a better ground. But considering they come loose every so often, I'm worried about rust down the road. I should probably just do it.

Maybe re-mounting the antenna will clear up some of the 11-meter poor tuning. Who knows. If not, I'll adjust the antenna length as necessary. Shame I don't have one of those NMO to UHF (or was it NMO to N?) adapters. I'm rather curious to see what kind of shape the cable is in. I suspect there's a short extension on it, but I can't remember anymore.

Anyway, enough radio rambling.


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I still need to figure out what's up with the speakers. I'm really hoping they just had the cords yanked on by something and need to be plugged back in under the seats.

And then the 11m needs the antenna tuned. I played with my nanoVNA the other day to ensure I knew how to sweep SWR with it. I've done similar with service monitors, but that was some years ago.

Before I mess with SWR on the antenna, I need to disassemble both antenna mounts, clean the trunk lid around them, and reassemble them. They were both a little loose last time I went to take the antennas off (one started to come apart), and they're both filthy in the areas the rain cap covers when I use the car wash.

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I actually have a commercial GPS unit, like you'd see in a public safety CAD install. But it's big, and so is the antenna. The antenna isn't going to just tuck into the corner of the rear dash, I'd need to drill a hole in the trunk lid for it. And it's ugly, I don't want a big white disc on my trunk. And then the unit would need to mount in the trunk somewhere. I used to use it with the TM-D700 in my work van when I was a radio tech.

But I'd rather another little puck-like think I can tuck into the back window, and I'll probably re-use the power supply from the Garmin. It's in a 12v accessory plug form-factor. I'll take an old PS/2 extension cable and use it for the socket and cable, and crimp a DE-9 on the other end. The +5v can be soldered onto the appropriate wires from the mini-din, inside the shell for the DE connector.

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Once I had it inside and on the bench, I popped the power supply open and checked that it was actually operating properly.

Alas, the fuse was not blown. Connecting 12v directly to the input did not change the symptoms. 5v could be observed on the output (which makes sense, there's a version of this device that is USB powered, no power supply). I tried bypassing the power supply and providing 5V directly, no change.

Interrogating it with a command from the manual intended to retrieve settings provided no output either. I also tried monitoring it with a serial tool that tends to provide gibberish when connected at the wrong speed, in case it was outputting data, but my settings were incorrect.

No joy. It seems to be dead. So I guess I'm getting another GPS receiver. I found one for a reasonable price, but it's got a Mini-Din 6 connector and needs 5v power. So it'll take a little work to hook it up. But the price is right.

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