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Test Equipment

riverrat373

riverrat373

Active Member
I'm trying to build up my electronics bench equipment and need a little advice.I basically want to work on building tube amps,diy speaker building and minor repairs on vintage solid state equipment. So far I have: frequency counter, rf signal generator, a true rms digital multimeter, vacuum tube voltmeter, variable dc power supply, variable isolation transformer, digital soldering station and a basic tube tester.

I would like to add an audio generator and an oscilloscope. Since I'm working on a budget I have buy my equipment a little at a time! Should I buy the audio generator first or the oscilloscope?
 
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Ocilloscope! You can hook up to it's internal Square wave generator to fire it up, and learn what the settings do.

The audio generator was a very hard purchase for me, and there's not as much info on these floating around. You need one with low distortion, and best I can tell these are expensive lab models. A "normal" function generators is no good for this. I couldn't find much to meet this demand. Best I could do was one with only somewhat fair distortion levels.

This one"



http://www.parts-express.com/pe/showdetl.cfm?Partnumber=390-620



390-620_L.jpg
 
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I use my scope more the the generator . Does you RF generator have an audio band you could use ?



Barney
 
That audio generator has been made by several companies in several countries forever. I have two of them; an Elenco made in Taiwan I bought new from CS Electronics in ~1990, and an original Japanese Goldwood I got on the 'bay. These are good generators; pretty low distortion sine, good looking square too, if you go for such navel gazing. You can find creampuff ones on ebay for maybe $25-50.

I would get one of these, and another DVM or two. The best are the large-chassis Flukes. I got two 27s and a 73 on the 'bay for peanuts, and they all agree to three decimal places. Having several meters is a godsend for testing, since you can hook them up to all the critical circuit nodes with gator clips and not have to be poking around in high voltage with probes.

I hardly ever even get out my 'scope nowadays. The ear is a better test of that stuff.

Aloha,

Poinz
AudioTropic
 
Poindexter said:
That audio generator has been made by several companies in several countries forever. I have two of them; an Elenco made in Taiwan I bought new from CS Electronics in ~1990, and an original Japanese Goldwood I got on the 'bay. These are good generators; pretty low distortion sine, good looking square too, if you go for such navel gazing. You can find creampuff ones on ebay for maybe $25-50.

I would get one of these, and another DVM or two. The best are the large-chassis Flukes. I got two 27s and a 73 on the 'bay for peanuts, and they all agree to three decimal places. Having several meters is a godsend for testing, since you can hook them up to all the critical circuit nodes with gator clips and not have to be poking around in high voltage with probes.

I hardly ever even get out my 'scope nowadays. The ear is a better test of that stuff.

Aloha,

Poinz
AudioTropic
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That audio generator has been made by several companies
Click to expand...

Looks real similar to the LEADER I picked up on ebay for chump change..http://www.audiokarma.org/forums/showpost.php?p=2625406&postcount=8
http://www.audiokarma.org/forums/showpost.php?p=2623784&postcount=1
 
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Oerets said:
I use my scope more the the generator . Does you RF generator have an audio band you could use ?



Barney
Click to expand...

No, unfortunately! That would also save me bench space. The rf generator I have is the brother to the audio generator that Wmacky has a picture of. I picked it up on Ebay for $35.00 and it is in mint condition. I have not seen the companion audio generator for some time now.
 
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There are oscillators and generators. Sometimes the terms are interchanged. To me an oscillator provides a low distortion sine wave. Function generators start out as a square wave and then use some form of filtering to give a sine wave with distortion of at least 1%. I have an HP 204C oscillator that I use occasionally when I need to go below 10Hz. It's distortion is low enough for most work, and usually costs under $100. If you're working with tubes then you may want to consider a tube based oscillator, the HP200. Check this out HP200. I use a 20 year old Loftech, TS-1 test set. The latest version is sold by Parts Express. TS-1

Working on a tight budget? You can build an oscillator for $10-$15. See the attached app note from Linear Technology. I built it and it works great. If you have a computer there's free software to create sinewaves through a sound card.

If you have a generator then you need a scope. The Tektronix 4xx series are my favorite, but they're getting pretty old. There are also USB based oscilloscopes. If you go completely computer based be very careful with ground loops.
 

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Working on a tight budget? You can build an oscillator for $10-$15. See the attached app note from Linear Technology. I built it and it works great. If you have a computer there's free software to create sinewaves through a sound card.

If you have a generator then you need a scope. The Tektronix 4xx series are my favorite, but they're getting pretty old. There are also USB based oscilloscopes. If you go completely computer based be very careful with ground loops.[/QUOTE]

I have wondered about software based audio generators and if they work just as well. I have lots of computers(4)! I have a Dell netbook that would fit on my bench without any problem.
 
Whut he said. The scope I could do without, but I don't have an LCR meter, and I wish I did. Good ones are not cheap.

Poinz
 
For my work bench I use:
Dual ch oscilloscope
Signal tracer
Digital and analog DMM
Spectrum analyzer
Power supply
Waveform Generator
PC computer
 
For me seeing is believing. I can't work without a scope. for instance, a DVM won't show you that little burst of oscillation at the top of the waveform when an amp oscillates. that oscillation will melt you're tweeters and you may not here it.
 
d3imlay said:
For me seeing is believing. I can't work without a scope. for instance, a DVM won't show you that little burst of oscillation at the top of the waveform when an amp oscillates. that oscillation will melt you're tweeters and you may not here it.
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Agree 100%

I feel blind without an oscilloscope. The oscilloscope is for electronics like an microscope is for biology, you just cannot work well without one. Working analog electronics without an scope is like setting up a stereo without the speakers (neither headphones).

Now, If the OP has never used an scope then I would think he is a novice and should take some electronics classes. Electronics can become dangerous not only because of electrocution but explosion and fire hazard also. Many people get burn when capacitors explode trying to make or fix electronics. Even soldering can produce a solder burst and damage an eye.
 
AngelRa said:
... Electronics can become dangerous not only because of electrocution but explosion and fire hazard also...
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I am a strong advocate of safety glasses when working on electronics. Some solder in an eye 25 years ago was a valuable lesson.
 
I have way more test gear then I need in my lab. I've spent 30+ years as an engineer and a lifetime as a "collector" (pack rat) of audio and electronic gear. If you'd like some lab grade (Tektronix, HP, etc.) test gear really cheaply, PM me.
As to what you should buy first, that's a bit of a "chicken or the egg" type question. I think getting a scope and learning how to use it might be the way to go. There are some Naval electronics courses on the web that would be a good place for you to start.

riverrat373 said:
I'm trying to build up my electronics bench equipment and need a little advice.I basically want to work on building tube amps,diy speaker building and minor repairs on vintage solid state equipment. So far I have: frequency counter, rf signal generator, a true rms digital multimeter, vacuum tube voltmeter, variable dc power supply, variable isolation transformer, digital soldering station and a basic tube tester.

I would like to add an audio generator and an oscilloscope. Since I'm working on a budget I have buy my equipment a little at a time! Should I buy the audio generator first or the oscilloscope?
Click to expand...
 
An option for an oscillator is to use your PC. I found a freeware wave form generator that creates sine, square, sawtooth waves etc.

A scope is certainly a handy tool. Be sure to get the probes with the scope for they can sometimes cost as much as a scope.

Look for ham fests in your area. There are deals to be found there. I got an old Heathkit scope for $10.

'That auction site' is another option but you have to be careful. I found a 2 channel Tek scope, Tenma oscillator, HP Distortion analyzer and a couple older HP oscillators (I'm a sucker for older HP test gear). The Tenma's distortion is quite low. Usually look for surplus sellers who show the gear working (ie traces on the scope, meters deflecting).

Also look for sellers who have some kind of return policy. One of the first scopes I bought was a fancy 4 channel tek scope. In great condition with probes, manuals and all. The seller didn't pack it well and when the shipper dropped it off a 2 story building (as seems to be the custom) it crunched the corner of the scope. It still worked but the seller took it back, refunded my money and paid for the return shipping.
 
AngelRa said:
Now, If the OP has never used an scope then I would think he is a novice and should take some electronics classes. Electronics can become dangerous not only because of electrocution but explosion and fire hazard also. Many people get burn when capacitors explode trying to make or fix electronics. Even soldering can produce a solder burst and damage an eye.
Click to expand...

Good advice having a capacitor explode in your face is not fun.
 

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