Equiping a test/repair bench

[mb91w126]

So, I would like to begin to learn how modify , align. test etc, 10,11,12 meter radios.

What tools and instruments do I need ?
I'm trolling through some threads and picked up that a Tektronix 465B scope
w/ 2 100k probes is sufficient, along with a mfj259 antenna anylizer.

any suggestions for training DVD's / Youtube videos??


adTHANKSvance for all your suggestions!

 

[AudioShockwav]

See if you can pick up a copy of Lou Franklins Book called Understanding and Repairing CB radios For the Professional Technician.
It is a good source of info, even if it is a bit dated, the basic information is very good and written in a very easy to understand format.
Read,Read,Read.

73
Jeff

 

[TonyV225]

Im with Jeff here on this, Lou Franklin has some really great and cool reads that vare easy to understand. If you find something that is a bit hard to understand then reread it and I gaurantee it will come to you. Also I would pick up a copy of his first or simple to understand beginners book "The Screwdriver Experts Guide" read this short easy to understand book and then hit the "Understanding And Understanding" CB Radio book.

You will not be sorry I have them both and got them after I had dabbled in repairs and still found them interesting and informative. His first book mentioned above he explains parts and differences between part numbers along with showing some really cool tricks that I still use to this day when I dont have certain tools or equipment infront of me.


You can usually get these books in a set which is cool because you have them all in one order and ready to go as you finish one its on to the next. Another simple and cool read is "The Rado Hackers Guide" I also have this book cant remember the author but its really cool how they show things and explain them along with showing cool simple little mods.

 

[mb91w126]

Thanks!
books ordered.

 

[Beetle]

A couple of years at a tech school would sure help in learning the correct use of each piece of equipment (for a properly equipped bench you'll need a LOT more than a scope and a 259B). Don't forget the periodic requirement for instrument calibration also.

 

[mb91w126]

Thanks Beetle, good advise.
I found a frequency counter, now off to find modulation and watt meters.

any other items anyone can think of would help.
Thanks!

 

[Captain Kilowatt]

You know, over the years many people have asked the very same question that mb91w126 has asked and I usually don't respond to them based on personal feelings. Now that Beetle has taken the words out of my mouth I shall state my agreement with that. Having been there and done that myself I can attest that that is the best advice one could ever get. Taking a legit course will make sure you have a good foundation to build upon and like anything else if the foundation is weak so shall be anything build upon it. Learning "what" and "how" is fine but unless you know the "why" then it is the same thing as memorizing the answers to an exam. You may be able to ace it but you don't really know the stuff. Lord knows there are enough amateur extra licensees that prove that today. I should not have gone there. Too late to take it back now.

 

[Robb]

1) For modulation, don't bother with a meter. They aren't really accurate. An O-scope with a passive/inductive homemade RF pickup is absolutely the BEST way to measure accurate modulation. Seeing the waveform is really accurate. The passive/inductive homemade RF pickup can be built from scrap parts or for a mere couple of dollars if you must.

2) As far as watt meters go; I use the Autek WM-1. Pretty accurate at a fair price point. You can sometimes find them used - too. This meter can gauge the settings for a 10m/11m radio for PEP in the low scale range. This make adjusting the SSB mode ALC control as well as setting AM dead key with reasonable accuracy.

3) DMM's like the Fluke is most accurate; but others like Sinometer or Craftsman (I use these two) are OK too. Get/make some clip-on leads so that you don't cause shorts when poking around and testing hot gear. A must.

4) A dummy load like the MFJ-250X sells for ~$70 and can handle up to 3kw. But a Goldline 100w dummy load can be put in a gallon paint can filled with mineral oil and still take 1.5kw - and cost 1/3 of that - if bought used.

5) A fine signal generator is a must. This won't be cheap. I've tried, as I am a cheap Ham. Settled on a Hp 8656B for less than $300 and a real bargain if you can find one like that at that price point. Really; an important piece of gear - IMO.

6) The SINAD meter (Signal, Noise, and Distortion Analyzer/meter) can be used with the purchase of this simple desktop/laptop computer program below. Used for receiver alignment in conjunction with a signal generator. Only $39 if you let them know you are a Ham w/call sign when buying. Just need a simple audio cable (1/8" to 1/8" phone plug/~6ft long) from a computer store; then hook it into your LINE input of the sound card and then the speaker output jack on the radio being serviced.

http://comtekk.us/sinad.htm

7) A frequency counter is necessary too; I would not use the antenna analyzer as a reference for doing alignments. Probably damage it. Some of those Chinese counters sold on eBay aren't all that bad and sell for around ~$100/new. A local Ham uses one and he likes it; seems to be fairly accurate from the results I heard. However, they are only as accurate as the room temperature when using it (temp +/- will affect its accuracy to some degree) and just how well it was aligned at the factory. I have and use a Protek (Chinese) and a Hp. The counter you should look for should have a 8 or 9 place display, as it needs to be able to read down to 10hz/min. Those cheap add-on freq counters used for 10m and CB radios just won't cut it either; just not enough accuracy or places/resolution. You will need some clip-on leads terminated with a BNC connector for it too.

 

[Beetle]

Digital meters/test equipment are not necessarily any more ACCURATE than their analog counterparts. They are, however, a good deal more PRECISE. And that's not hairsplitting: accuracy and precision are values that are related, but they are not the same.

I couldn't help but laughing when I read "Sinometer" as a brand name. I'd never heard of it, but "Sino-" is a prefix (combining form) that means "China". So I casually predicted it would be a Chinese product, looked up "Sinometer.com", and there it was!

 

[Robb]

Digital meters/test equipment are not necessarily any more ACCURATE than their analog counterparts. They are, however, a good deal more PRECISE. And that's not hairsplitting: accuracy and precision are values that are related, but they are not the same.

I couldn't help but laughing when I read "Sinometer" as a brand name. I'd never heard of it, but "Sino-" is a prefix (combining form) that means "China". So I casually predicted it would be a Chinese product, looked up "Sinometer.com", and there it was!

I thought the same thing. HALTED/HSC Electronics in Santa Clara CA sold me the meter and told me I would be pleased with it and backed it up 100%.

Bought some precision resistors of various values (low, med, and high) to test it out, and the resistance was spot on. It can test electrolytic caps and transistor hfE too. Not a bad meter for the price point. Model VC9808.

 

[cjruger]

See if you can pick up a copy of Lou Franklins Book called Understanding and Repairing CB radios For the Professional Technician.
It is a good source of info, even if it is a bit dated, the basic information is very good and written in a very easy to understand format.
Read,Read,Read.

73
Jeff

Wow. That book is not cheep !!

 

[Radio Tech]

Lou's book goes for rediculas prices on ebay. The book is now back in print but is in a spiral binder and is close to the original price as before. At least the last time I checked over a month ago.

Just want to comment on beetle and captain kilowatt. Having all the fancy and latest equipment want make you a tech. Understanding how a circuit works it what makes it. The most expensive gear I have is my IFR 1200s service monitor. Over 9 grand new at the time. Most of my stuff is dated but works fine. The newest piece of equipment I own is my OWON DSO (digital storage oscilloscope). The only reason I bought it is because I am now learning pic programming. Rest of my scopes are old. Have like 7 of them.

A lot of stuff you can build yourself. Plus learn while building.

 

[Robb]

Nothing like having experience in order to learn something. Nothing like getting your hands greasy when changing the oil in your car for the first time. No one can get anything done unless the effort is made. Even if one makes mistakes, so long as they can be honest from those mistakes can one gain something back.

The books are helpful; but there still must be effort made to make that book knowledge practical. Some repairs can be learned through finding common faults known to certain models online if you dig; but this isn't always reliable nor definitive.

CB Tricks is a fantastic site for info to work on radios. Schematics and Service Manuals for a lot of radios both old and new can be found there. The very best site there is for gobs of radio tech info - IMO. Defpom is another very useful site. Otherwise, you can go broke buying SAM'S Photofact manuals and they really aren't any better than CB Tricks. Read some of the schematics and service manuals and dig deep. If any questions need answering, you cannot do better than this site! Lots of seasoned tekkies here.

If someone is going to learn to align a radio; then they must consider taking it at single steps at a time. Check your work. Then ask questions - like on a forum like this. Getting familiar with all of the electronic components inside the radio and what they do/how they behave is a very important first step. What is a diode; what does it do and how do they differ? How does an electrolytic capacitor and a ceramic capacitor differ? What is the difference between a MOSFET and a bipolar transistor? Medication? lol! Learn at a rate that is fun for you, as it will be.

Not everyone that is into radio as a hobby wants to learn the alignment aspect. Same goes for repair. Learning how to fix them will come far slower than learning how to align them. Fixing a radio can be easier to do while aligning it, as you will find a portion that won't align if it is broke. You will know where the problem area is to some degree. But then; that is where the fun begins. If you can call it fun. You are now faced with learning and knowing more than you did before; can you do it?

It all comes back to motivation. Do you feel angered and frustrated when so many of the tech gadgets bought over the years go belly up and there isn't any remedy for you? Laptop broken? Power supply went poof? LCD monitor lasted only 2 years? Got a nice radio for a song and now you think you can fix it? Can you get there? It's junk if it stays busted; and a new found tool if you can get it to work again.

It will take time to understand the test gear controls and even more time to understand how to apply it. There are LOTS of YouTube videos for using test equipment; so there is help. Start out small and only do what you have the tools for; make notes as you go along. A wattmeter, DMM, RF pickup, dummy load, cables for the counter and the DMM, and a freq counter is the place to start at. About ~$300 for the stuff if you hunt and choose carefully. Doing receive alignment is a bit more costly and can be a bit complicated. Just start out small. Getting real familiar with just one radio to begin with translates well to other radios; however SSB radios are more complicated than AM-only radios.

Get a junk radio and see if you can fix it; that way you aren't out anything. They can be had for little money. If you fix it, you might feel like King Kong - but you are not. Not yet; but give yourself some credit for getting your feet wet. If you didn't fix it will end just up in the junk drawer and a sore spot for frustration the next time you look at it.

Aligning a radio takes patience and learning a skill. I give a lot of credit for those who have the years of experience doing it day in and out. Even those who are trying to learn it. Experience along with persistence and patience - one will find out - is everything in working with electronics . . .

 

[mb91w126]

I want to thank all those who responded and relate that I have read each post for comprehension and understand the messages within.

The advise on the text's, classes, and equipment is spot on.

My first book arrived today along with a few disposable radios.
The scope, counter and generator have been identified and other components will be trickling in over the next few weeks.

Your support is very much appreciated.

 

[2FB327]

Thanks Robb

Thanks for taking the time to answer the post, it's very helpful to me.
I'm on that road of building a bench and trying to learn.

Questions: Freq counter hookup, I have been reading some service manuals and it calls for the use of a freq counter.
I have had the kind that plug into the back of the radio, but what would you recomend and how do you hook it to the radio?