Understanding & Repairing CB Radios and other books by Lou Franklin.

[JayMojave]

Hello BrettL: Yeah try Kens Electronics at:

Ken's Electronics, (Wholesale & Retail Electronic Parts) Kalamazoo, Michigan has CB repair parts & tuneup manuals and CB radio schematics

Don't know much about these book just that they are available.

Had to fix a few radios over the last year or so. I am not a day in day out experienced bench technician so I had to go slow looking every thing over doing a real good easter egg hunt inspection of everything.

With the older radio made in the later 1960's I replaced all the Electrolitic Capacitors first as some showed signs of goo leaking out and deformed shape. Next was the burnt resistor contest to see how angry I could get replacing all of them. A new 115 VAC power cord and finding the original mic I was trouble shooting the radios receiver, tracing down where the signal was lost. I got lucky finding a bad tube, the signal generator and signal tracer worked as advertised. I R a Tech.....

The later ARRL Handbooks has a really great chapter on Trouble Shooting and such, very good. I am sure if your search E-bay and Amazon, Radio Repair Trouble Shooting books will show up.

Trouble shooting radios will surly sharpen your radio repair skills, and make you a much better technician. Practice practice practice...

As soon as my employer comes up to speed and retires me I plan to set up a radio repair bench, and work on radios as you say. I have plenty of older NOT working radios, that I plan to fix and get on the air. First things first, I bought a neat new AM/FM Stereo Radio with speakers on each side of the bench, more important that a soldering iron and test equipment.......

Jay in the Great Mojave Desert

 

[LoyalServant]

First things first, I bought a neat new AM/FM Stereo Radio with speakers on each side of the bench, more important that a soldering iron and test equipment.......

Not sure I get that one
I guess you need something to listen to tunes with while your scratching your head

 

[cmdrwill]

You have to take a break some time...

 

[Dawn]

It might be a better investment to find a decent, general coverage communications receiver that has an S meter for your bench. You not only get the entertainment, but is a worthwhile piece of test equipment on a low investment bench. Find one with a separate, adjustable mode switch that is independent of the band. Extremely useful to "listen" to stages and attach a probe to the antenna for low level, tuned, relative gain indications on the meter. A receiver that goes up to 6M would be ideal to check CB 2nd harmonic suppression or tune a trap if you don't have access to a spectrum analyzer or service monitor. Two items you're not going to think of purchasing for a starter or intermediate bench. If there was a 2nd priority, consider a mini fridge and a coffee machine. Far more practical then a stereo.

 

[BrettL]

I like listening to people talk skip when I worked on things. Not sure why. I guess it was the enjoyment of the sound of people talking on radios. Most people my age don't like this kinda stuff and have nothing in common with it. I'm still looking for a couple of pieces for my test bench and very anxious to get started. I did get me a 5x magnifying desk light and a small vice the other day. Things will fall in order soon. Then it will be time to catch stuff on fire, get electrocuted, and call 911 for help.

 

[JayMojave]

Hello All: Yeah good call Dawn having a good receiver. Entertainment and use as test equipment.

Lets hope you don't have to call 911 or the Fire Department. Handling High Voltage in tube radios and linear amplifiers I have the utmost respect for, and discharge all the power supply Caps before looking around them.

Again referring to my good friend Bill Good who was a full time Bench Technician had some pretty expensive audio gear and some impressive speakers. One time while having a BBQ at his place,
with other distinguished radio enthusiasts, I asked Bill why all the expensive audio equipment. Bill replied: "Because I am worth it" Roger that...

Tunes are a important part of being retired and having radio repair bench, I can tell.

Jay in the Mojave

 

[k3cfc]

Someone once said " information' is hard to come by but if you fill out a work order i will be happy to fix it for you. For $100.00 these books will pay for themselves in a few repairs.

K3CFC

 

[BrettL]

What kind of books do you have K3CFC?

 

[Dawn]

You're not going to learn anything from many of these cheat books. They are mostly connect blue wire to here, cut trace there, add switch and wires/diodes here. Sometimes they have after a few years of publication some known issues with particular chassis. That was fine and great then providing you already knew what you were doing and these books just gave quick cheats to make an extra buck by doing illegal mods.

Now you have another issue. Age. A whole new set of problems caused by contact oxidation, component deterioration, results of bad mods and production/batch problems and of course obsolete/unobtanium parts. None of these cheat books are going to help you there. Only a good understanding of the circuitry and good docs such as sets of sams photofacts or factory service manuals will help you. Those are the books you need to be accumulating in addition to the understanding of the theory.

Get on Allibris, Amazon, or other used book list. Look for books from authors like Forrest Mims, Forrest Belt, John Lenk, Ed Noll. Search out the net for archives of the amateur magazines like 73 that for many years had conversion articles for particular models. Most of those articles also had a summation of that particular radio's theory of operation and alignment. Dave Ingram and Bob Heil both wrote books on 10M conversions with lots of circuit theory that was unfamiliar to amateurs. Since CB was considered a business band, many books on commercial two way radio had sections reserved for that. Forrest Belt for example treated CB's in his commercial radio service books. Search by book publishers like TAB, Howard Sams, Cowan on CB repair titles. Look for titles written after '78 for more detail on 40 channel PLL. Most all these books can be bought for 3-4 bucks plus library rate shipping. Search E-bay. Maybe somebody is selling a student copy of Hickok's tech school CB training material. You mention your friend has all these radios. Start figuring out what he has and look over the SAM's listings on Ebay and other websites. Non-demand and 23 channel titles sell for $5 or less plus shipping, often less if you buy many. High demand ones like the 148gtl/2000 will get a premium.

If you want to see the quality of these red blue whatever color nonsense cheat books, go over to CB tricks and download the entire Secret CB series. Have you done that? Downloaded manuals if there are any there for some of the sets your friend has. Sit down with that material and get a good look. Secret CB is pretty much representative of an entire cottage industry of cheat books that are of little use teaching you anything about CB theory.

You haven't told us if you received your set from Lou Franklin. It's been some time now. He's very prompt with his kits, so you should have them by now.

You're asking a lot of questions, but so far you haven't told us what you now have in test equipment, radios from your friend, or service litterature. You learn hands-on. Get a simple 23 or 40 channel am set that's well documented with litterature you can easily find and stumble your way around it. That's what some of are here for. I don't see you working with the resources you already have even if it's just a power supply and a multimeter.

Get moving Brett.

 

[BrettL]

I am moving as fast as I can. I have my oscilloscope, power supply, dummy load, ect. As far as the test equipment you mentioned I have been looking for them. Everything you mentioned at the time I could find all over the place and on ebay. Im currently bidding on a signal generator right now. Hope to be highest bidder. It has been tough trying to obtain these test equipments . Vendors are wanting practically new prices for them. I have also been looking for the 5128 and the 9150.

Sorry I did take a few steps back by purchasing some amateur radio stuff. I will get back on track.

Still looking for a BK cb test panel , universal test center, station monitor, ect.. I will try much harder this time. Hope someone puts more of this on ebay. I did by some plastic precision tools and some test leads, clips and such...Many other new tools. So back to the test equipment. I am on it I promise.

 

[k3cfc]

When i bought my B&K test they were on close out but new. this was in 1980.dummy loads are ok but a real antenna will tell the story. BTW B&K go for good money because the 1020 & 1040 are rock solid. mine looks like the day i took them out of the box.

 

[BrettL]

Im in the works of getting a BK-e200d solid state signal generator. I have been trying to find a Universal Test Center Tenma 72-9150 or 5128.

I was looking at a Tenma 72-5085 but not sure how dependable they are. Also I'm looking for the same BK 1040 test panel you have.

A few weeks ago there were multiples of all these test equipments on ebay and now there are none. The ones I do find are a little risky and shipping costs as much as the test equipments.

I'm patiently waiting. If you decide to sell then PM me.

 

[Dawn]

The E200d is quite a remarkable little analog gen for the money. Certainly better then anything else in it's price class or several times more. It is quite stable, but one thing about it is how remarkable flat the output is across the main bands and the accuracy of the attenuator. This is not a simple attenuator as found in similar hobby and low cost service generators. It's a bonafide T pad swichable step attenuator for the output. The upper level decade attenuator controls the gain on the oscillator output and then feeds the low level step attenuator. No "pulling" on the frequency when using the steps. Hooked up to a rf millivoltmeter across a 50 ohm termination, from the lowest to the highest fundamental band, level varies less then +/- 1db. It also is remarkably well shielded inside for a generator of it's class and has a metered output for both RF and Mod. I've repaired a few of these and problems are often quite simple. No modulation audio is the most common. Often realigning the 400 hz pot will cause it to restart. That was solved by a factory mod in later units. Good idea to do it anyways and then retune the mod frequency to 1khz instead of 400hz which has become the standard mod frequency. Another problem that's simple is the dial doesn't track the frequency. The reduction veneer has grease that's by now getting hard. That tightness causes the set screw in the fiber shaft coupler to get loose. A little naptha will clean out the hardended grease and use some moly lube for the next 40 years. Use a frequency counter to reset the dial and retighten the hex set screw with a little locktight. In some cases, some idiot has fried the input of the attenuator with a transmitter. Not really a big problem as you can disassemble the shielded step attenuator easily and replace the first two resistors. The front panel uses a once common amphenol microphone connector for the output. It's easily replaced with a bulkhead mount BNC. You can usually find plenty of them on Ebay cheap. Some people add a tap from the shielded oscillator compartment to a double shielded jack somewhere on the chassis to provide a counter output. There's several direct mods, but one using a fet as a source follower is probably the best. You really don't need it on a CB as it's channelized. Once the crystals or PLL is set, just keep the frequency centered for max output. The BK2040 PLL CB generator is a huge unit and really unnecessary at the price they go for. You can usually by a lab grade, synthesizer generator for what a working one goes for. It does have one nice feature though. It has a noise generator that's built inside the attenuator. That's an unusual feature only found in a few CB gens where otherwise and external pulse generator would be combined in a T connector in a lab setup. You'd only need that if the radio has a tunable noise blanker. It also just has a fixed 455kc output. That's great for AM sets or lower IF's if it's double conversion. You still would need a gen like an e200d to troubleshoot or provide a signal source for around 9-11 mhz where most SSB sets use a crystal filter. The BK-2040 doesn't have that ability. It also has a hidden little speaker for a crystal callibrator. You won't even have to worry about using that nowadays with a cheap frequency counter.

The Tenma 72-5085/Metex 9150 is very dependable. It's sister that was never marketed by Tenma, the 9160 was unstable at the highest 10mhz range of the function generator that sacrificed the lowest range to use the same switch positions, otherwise they are near identical. Early 9160's came with a true reading RMS DMM section for AC that found it's way in later production 9150/5085's anyways. Nothing to be concerned about. The earlier Metex 9140.Tenma 72-1005 was an earlier model that near identical except the counter only goes to 150mhz and the DMM is not autoranging. The autoranging ones in the later models are kind of slow anyway. If you're comfortable using a fixed range DMM, it's much faster. Unless you have a reason to go above 2M, the counter's 150mhz limitation is sufficient. A cheap prescaler kit from one of the kit companies can extend the range with sufficient accuracy for amateur use. Another difference is the 9150/72-5085 that goes up to 2.4ghz has a TCXO for higher stability whereas the 1005/9140 doesn't. I wouldn't pay more then $75 for the earlier 1005 and no more then $150 for the 9150/72-5085 providing the function generator's veneer isn't damaged as I've mentioned earlier.

 

[BrettL]

The books I mentioned above I ordered . I take them to work and read them on lunch breaks and read a little bit before bed time most nights. I must say the spiral back versus the paperback is not better. It may be better so it can lay flat while you work on a radio but the holes where punched too close to the edge of the pages causing them to get weak and fall out. A new comer as myself the book is teaching me what things are doing inside a radio. Better than a website telling me to jump c142 to r23. Put 150 pf across .......etc. It's slowly painting a picture of what's going on inside.

 

[Dawn]

Nothing like picking up a working,simple, crystal controlled, channelized rig for a few bucks that nobody wants and cheap SAM's off Ebay for it. Work your way through the transmitter and receiver chains to get a feel for what's going on. See what the oscillator sections look like on your scope, compare the working voltages with the docs, get a feel for working through a circuit from base to collector and see the stage gain. Nothing to lose and you get hands on experience. Nobody ever learned to troubleshoot a radio just by reading a book. You have to roll up your sleeves and smoke a few semi's with probe slips and lots of "oh *****'s" where you end up figuring out the mess you made. Like the old line about having to break some eggs to make mayo. Work your way up to a 23 channel crystal mixing set to and then an early PLL unit. You probably have the pll chip book too with the set. Download data sheets on commonly used chips and semis and verify the data states and inputs and outputs on those units.

If you did the above and learned something along with the book, you probably will know more then 95% of the so-called cb techs that hang a shingle and butcher people's radios every day using cheat books and BS upgrades like magical capacitors, fancy knobs, and blue LED's.

 

[JayMojave]

Hello Dawn and all other Distinguished radio Enthusiast's: yeah and all the rest.... (humor)

GOOD GOING Dawn, great advice from a obviously experienced bench repair technician. Playing with a cheap radio to sharpen your skills and get a feel for what the radio does, that's a good call. Book smarts is a good thing to have but hands on like you said builds the Tech.

On Soap Box...

I have to take a poke at the Academic World here referring to some of the Electronics Books out since the 1960's and so on. As many books are filled with PHD goof ball material that only advanced studies need to be exposed to.

And the removal of Industrials Arts Classes in the Junior and High Schools to make room for more hand waving (nothing to support getting a job) Academic gobble-dy-gook that is supported by the education groups that support the Honor Societies, and other special Academic only functions. While the Industrial Arts (the shops) are left out. A bad call from the Academic inclined hand waving do nothing school leaders and administrators. Thats why its costs almost 100 dollars an hour to call a Plumber or Electrician.

Ok off soap box...

Jay in the Great Mojave Desert

 

[LoyalServant]

If you did the above and learned something along with the book, you probably will know more then 95% of the so-called cb techs that hang a shingle and butcher people's radios every day using cheat books and BS upgrades like magical capacitors, fancy knobs, and blue LED's.

Aww man but those blue leds with the horribly designed PWMs are cool!

But the audiophools love them some speshul capacitators, big schottky diodes and 10 gauge wire at the dc input jacks of their radio! it helps the volts get thru!

 

[JETDRIVER]

trouble shooting info cb radios and ham

hello Brett, hope you get to see this. i suggest you track down the B&K 1040 Service master manual
this not only has all the details on connection and how to test using all the functions,
but it has one of the best troubleshooting sections for cb radio you will find. these units however were built before 40 channel was introduced but the manual still gives a really great description on radios and finding problems.
Also hunt the internet and download magazines like ELEMENTARY ELECTRONICS and search thru the editions they have a really great BASIC ELECTRONICS section that also covers radios and a large coverage
of cb radios from valve to pll.
there are also heaps of other magazines available online from those days with heaps of information.
The internet is full of info it just takes some time finding what you want besides SECRET CB there is S9
magazine also. it just takes time searching and getting the right info, dont forget to look at ham radio also
for info and projects, there are an incredible number of very smart people who are hams both amateur and professional engineers.