Thread: How I built my Best CB Mic Ever!
- 08-17-2009 04:43 PM #1
- Join Date
- Jul 2009
How I built my Best CB Mic Ever!
Man, I love my Uniden 78ltx CB. Not everyone knows that back in the 70's when Cobra made a name for themselves for their Cobra 29 Classic that UNIDEN WAS MAKING THE ELECTRONICS FOR THOSE RADIOS! - The new Cobra 29 Classics are not the same quality inside as they were decades ago, however my CB radio guy advised me the new Uniden 78 series is as exact as any new cb radio can be to the old Cobra 29 classic. All of the mods and toy circuits work the same way. So I bought my Uniden 78ltx in 2002, it survived a bad wreck in which I flipped my 4x4 about 6 times, yet it still kicks ass on the wattage meter.
In these mountains of eastern Kentucky it is very difficult to be able to talk back to most of the drivers one can hear on a "barefoot" (stock 4 watt) radio. Most drivers here have super-tuned cb's, or modded import cbs etc... and the real serious ones have the big boxes, often with an output of 100 watts is common here. (not legal!!)
The leos here don't even recognize a big radio that has been super-tuned, so they never say anything, but if they spot a big amp box they have been known to get on to the drivers, but I dont think they have the authority to act on behalf of the FCC, can they?
To Da Point: After I lost my favorite pickup truck in a wreck, i used my insurance money to outright buy out a new 2009 Chevy Cobalt LS Coupe XFE- great price, great mileage at 37 highway, and real fun to drive. Little by little I got things in order. I ordered a brand new Wilson 5000 Mag Mount Antenna, which I believe is the best quality in the business, mainly due to the whip being made of copper and coated with silver- great conductors make great antennas.
Next I had to do a little engineering to figure out how to best fit my large CB into such a small sub-compact car. I figured in seeing that the faceplate was looking old and scratchy anyway, that the best and safest spot was to mount in below the dash underneath the steering wheel. I sawed off a piece of wood to reinforce the plastic and used 2 inch machine screws and washers with ridges that caught on solid. The mount worked perfectly.
Next I routed all wires, hid them, got them tucked out of the way. So I get my SWR under a 1.0 and figured it was close enough for a radio check. Next I plugged in my brand new $70 "Telex Turner Road King 56 Chrome Special Edition Mic"!! It's supposed to be chrome, but was plastic when I received it (a shame). But, I figured it had to be better than my stock Uniden mic that was getting some static. I get on the interstate and drive many miles asking for radio checks. I asked many times before I got anybody. Bad News!!! My $70 mic SUCKED BAD!!! Everyone could hear my dead-key, but my modulation was nowhere, even with the gain turned all the way up!! It was useless, this mic was very very bad when fitted to my CB. I put the stock Uniden mic back on and all radio checks were pretty good, but not perfect. Some heard some static, and others said my modulation still needed improvement.
So, here I am with one cb mic with a great looking case that sucks and cant be returned, and another old stock mic that has an ugly dirty case that works good but has static and modulation issues.
So I did the obvious. I got out my large toolbox of electronic tools- For circuit boards and SMT parts). I decided I would take the best of both mics and combine them into one good mic!!
I first dissemble both mics. To my shock neither mic had any form of shielding. No wonder my cb transmissions sometimes set of my V1 (very rarely)! I first refitting the cable end that screws to the CB radio, as this was the stress point on the wires I figured was causing my static. I unscrewed the tiny screws, tucked the wire up in the plug much tighter, then placed a few wraps of black tape around it and on up the cord a few inches. Next I tighten the screws back, but not too tight to break the tiny wires. Next I take ONLY the new "CHROME" mic case to mount all of the Uniden mic parts inside. I noticed the Uniden had some thin sponge rubber over it's raw mic, and it's original case had 3 or 4 thin slots cut into the case where one talks at. No wonder the modulation was poor, there was not enough surface space between the case and the mic element!!
Next I had to search very hard at Walmart for the perfect glue. I needed something stronger than crazy glue that would bond parts together like a good weld, yet still work under very hot and cold temps. Finally I found the perfect glue- It was made by LockTite and was for Extreme Temps! Cost $5.00.
At home I cemented the Uniden Mic element with only the thin sponge rubber piece on to the SCREEN of the chrome case- thus raising the surface area to talk at by a large margin, and should prevent any muffling as in the past as well!
Now came the hard part: I had to take the mic button and cement in on to the back of the magnet of the uniden mic element I just glued to the inside of the chrome mic case. It was tricky but I found the perfect angle and used as much glue as I thought I needed. This would be a high stress location due to the fact the button would have pressure applied to it every time keyed up. I used a small C-Clamp to hold these parts together for almost 24 hours.
After 22 hours or so I took the C clamp off and was very happy to see that the glue was holding well, almost like a solid weld!! I next had to cut a piece of plastic to make the chrome button extend just the right distance so when pressed it would operate correctly and pop back out when not pressed. Again I had to glue it and wait.
Finally, I got some tin foil and cut it to fit the inside of the two parts to the chrome case. I also taped over any wires to prevent shorting to the case shield. The bare ground wire was so large that I just sealed the case up with the ground wire touching the tin foil perfectly. All screws were tighten, and the button seemed to work fine. So far so good. I plugged the mic into the cb and my meter showed it was functioning.
Now all I needed was some radio checks. My first radio check was from my car sitting in my driveway. First try I got back a loud signal from a driver that advised me the mic/signal sounded loud and clear with no static and great modulation. I was shocked when I learned he was on the interstate because I was located down in a deep Vally many miles away from the interstate way over top a large mountain!
I tested the mic for nearly three days and every single report was more than positive. I am now getting the best radio checks that I have ever got. People tell me I'm blowing smoke, burning them up, ten pounds, and I often can be heard further than I can hear the barefoot radios. So far I'm sure I have talked back and forth for 15 miles through some mighty large mountains, and after dark Im sure it's farther away but I need other CB users to have enough power to yell back at me, as that has now become a problem.
The guy that worked on my supertune told me that the stock Uniden 78 Mics were some of the best and clearest he had ever used. So when I managed to increase the surface area by allowing one to talk straight through a black screen and thin sponge rubber, it's almost like having nothing in between the mic element and my face. It improved the modulation at least 100% based on radio checks, and I'm now able to be heard many miles further than I ever have been advised before I re-made my microphone. It rules.
For those Uniden CB Users, Or anyone that would like to copy-cat my design: - They happen to sell what appears to be the exact same chrome-plastic cb case at popular truck stops and online. If you have a stock Uniden 78 mic it will greatly improve your modulation and clarity, not to mention you range, by doing what I did. Just buy the chrome case PARTS instead of wasting the $70 on the Turner mic like I did. All one would really need is the stock Uniden mic, the plastic chrome case sold at many truck stops, and the Extreme temperature LockTite glue/cement sold in the automotive section at Walmart, and a small C clamp, and tin foil. These mics should of been shielded all along, and I do feel connecting the tin foil shield to the ground wire really helps these mics sound better, stops interference with radar detectors, cell phones and more. With the increased surface area of the mic exposed to your talking through a screen and foam rubber, rather than the small slots Uniden has on their cases (see Uniden mic pic below)- Unidens method of small slots in their mic cases makes it more likely to muffle your voice and get poor modulation.
I am NOT selling or Spamming here, I just want to show the members a picture of what the chrome case looks like when purchased by itself as a part only, and where to find it. Cost is $10.00 to $16.00 USD. However they are cheaper at some truck stops and postage can be high.
Chrome Microphone Case - Road King 56 40988 - Electronics Superstore www.WalcottCB.com
BELOW is what the STOCK Uniden 78 series mics look like. It is the best stock mic I ever used, yet is GREATLY improved when one takes the guts out and installs it into the cases above! (Just need the LockTite Extreme Temp Glue and C-clamp, plus tin foil to make shield):
Sold at most truck stops, or here is one of very many places to find this mic that I used for the "guts" to stuff into the above chrome plastic case. Cost is $20.00 to $30.00.
Uniden MK516 Replacement CB mic for Uniden PC68XL and PC78XL
Last edited by Jammer; 08-17-2009 at 06:22 PM. Reason: fix typos
- 08-17-2009 08:01 PM #2
Re: How I built my Best CB Mic Ever!
Great job! I love tinkerer stories like this. And this is exactly what I have been thinking of doing myself. The thirty year-old stock mic on my Motorola CB is wore out and lame, and I want to upgrade to a good power mic. But I don't like the look of most CB mics, because the Motorola is such a professional looking radio. So I want to have my CB guy take a new Motorola professional mic I have, gut it, and install the guts of a nice power mic into it for me, just like you did. Your story gives me more faith that this can actually be done!
- 08-18-2009 08:32 AM #3
- 08-18-2009 11:33 AM #4
- 08-24-2009 02:12 AM #5
Re: How I built my Best CB Mic Ever!
Beautiful chrome! I love that CB Mic, Any way I could buy one from you? (Im too lazy to build one myself) Hahaha.---------------------------------------------------------------
CB: Midland 1001Z, Wilson Lil' Wil' Antenna
- 08-29-2009 04:03 PM #6
- Join Date
- Jul 2005
- Great Lakes
Re: How I built my Best CB Mic Ever!
Great story. Thank you.1. Escort Redline 2. Bel STi 3. V1 3.893C 4. Whistler CR85 5. Black X50 6.Whistler XTR 695SE 7.Escort 8500 8.Escort 9500IX 9. Whistler 3600 Remote unit
10. Blinder HP 905 LJ, Quad head11-13 Cheetah C50 RLC detector, Tom Tom 540XXL, Garmin Dezl 760LMT14-20 Scanners Pro 43,57,94,& Regency,Uniden BCT8, Uniden 996T
21. Car/Modded Galaxy 959 CB, Power mic, Wilson 1000 magnet mount, Palomar Low-drive Amp
22. Truck/Cobra 148GTL CB, RoadKing Mic, 1 Predator coil whip, Blue Lightning Low-drive AMP
23-25 Spectre II RDD, 2 VG-2 Interceptor RDDs
26-27 RS HTX-242 Ham radio, Uniden VHF radios
28. Zaon PCAS MRX collision avoidance system (Airborn Vascar detection)
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