Buying used equipment...

Discussion in 'General Electronics Chat' started by thakid87, Nov 5, 2009.

  1. thakid87

    Thread Starter Active Member

    May 23, 2009
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    Hello.

    I am looking into buying a few used equipments, power supply, function generator, oscilloscope, etc.

    However, I am broke college student and want to stick to used, because its cheaper. I was curious if I should stick to certain makes or if it would really matter?

    Any advice?

    Thanks.
     
  2. bill l

    Member

    Oct 11, 2009
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    87 was a good year......

    anyway,

    this is what i have been doing.

    1st - craigslist. occasionally, you can find gear that way. i picked up a tek 2246a scope for less than a hundred.

    2nd - ebay. not to buy, but do a search in the test equipment category and reduce search to local auctions. this will provide you with local sellers that are most likely liquidation houses. if you can do basic repair and have some known standards, you can get the "broken" stuff cheaper that way. doing this got me a fluke 8012a, a fluke 8600a, a hp 3311 function generator and a wavetek model 23 digital synthesized generator that still needs a 7 dollar op amp chip to be fully functional. all that for less than 60 bucks.

    3rd - pawn shops, but they typically want an arm and a leg for a used peice of crap.

    other than that, that is all i can offer.

    bill
     
  3. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    I was able to put together my measurement equipment set over a 5-10 year period by looking for inexpensive buys on ebay and other places. It takes perseverance, luck, and lots of research to find out what things are worth. You also have to set a limit for what to spend on one particular item and if you don't get the first five you see, wait patiently for the next one.

    As Bill mentioned, if you are willing to track down documentation and fix broken equipment, this can be a great way of acquiring some nice stuff.

    As to brand names of equipment, that's up to you. I tend to favor HP equipment, but any of the major names produce good stuff.
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    You guys are missing a big bet, HamCons. Hams are the weirdest group in the world, they will tell you every flaw, every improvement, and then dicker ruthlessly. Some of the most honest guys in the world IMO, and they do have good stuff.
     
  5. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
    2,040
    287
    Check with your local amateur radio flea markets and such. There's usually some good equipment at bargain basement prices...or free!


    Take advantage of being a broke college student! Having to "roll your own" is great training for being a resourceful engineer!

    Eric
     
  6. bill l

    Member

    Oct 11, 2009
    30
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    yes, forgot the hamfests.
     
  7. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
    2,040
    287
    From the Opus of Amateur Radio Knowledge and Lore: :D

    O, Silly Scope
    Sooner or later, you’re going to want an oscilloscope in your ham shack. Having an oscilloscope in your ham shack is like walking into an operating room with a stethoscope around your neck. Even if you don’t have a clue what it does, it makes you look qualified for something.
    Oscilloscopes always look cool, and it seems the older and less useful they are, the cooler they look. Every B-grade science fiction movie ever made had an oscilloscope in it, loaded with lots of knobs that didn’t seem to do anything. An oscilloscope was the traditional busy box for mad scientists.
    Now, making the transition from mad scientist to competent electronics troubleshooter isn’t as hard as it seems, and it’s well worth the effort.
    An oscilloscope is nothing more than a graph that shows the relationship between two things that change. Most often those two things are voltage and time.
    A voltmeter is most useful for measuring things that stay put, while an oscilloscope is most useful for measuring things that move around a lot. You can also use an oscilloscope for things that don’t move around, but it’s usually a bit of overkill for that, unless you already need a ‘scope for looking at things that do move around anyway.
    Now, in order to get those moving-around voltages from your patient on the operating table...er...workbench into your cool-looking oscilloscope, you need a thing called a probe. Like your voltmeter, this is one place you don’t want to skimp. Get the best scope probes you can afford. You’ll want at least two of them: one a direct 1:1 probe, and a compensated 10:1 probe.
    Now, if you have an oscilloscope that was manufactured some time after the Baroque era, it probably has usable triggering as well as fairly decent time and amplitude calibration. But don’t count on it.
    Unless you’re made of money, most likely your first oscilloscope will be a vintage product, containing a fair number of vacuum tubes in addition to the main CATHODE RAY TUBE display. It will weigh somewhat more than a 1956 Thunderbird, but slightly less than a Buick Roadmaster of the same year. Fortunately, these usually come on a cart with “wheels,” which were another invention that came along a few years later, as a product enhancement.
    After you bring your “new” oscilloscope into your shack, you will want to turn it on and let it warm up and stabilize, a process that can take anywhere from a half hour to a week.


    Eric
     
  8. jgessling

    Active Member

    Jul 31, 2009
    74
    14
    I second the motion regarding ham markets. Or just plain regular flea markets, it depends on your location. I'm in northern California and have accumulated several pieces of equipment over the last few years, not all are working yet, but enough to keep me going. Last weekend was the last for the year of the Livermore Area Radio Klub market, there were a couple nice pieces there, didn't ask the price, but as another poster pointed out, these sellers are as honest as can be.

    As we hunker down for the winter I wonder are there any other online sales besides epay? There used to be vintage.org marketplace but it's defunct, any others?

    Regards, Jim

    p.s. one great deal that I got is a fancy Tektronix DMM for $33. The seller wanted more but I showed him that was what I had in my pocket so the deal was made.
     
  9. bill l

    Member

    Oct 11, 2009
    30
    0
    i'll tell you that i have always loved using scopes. i currently have two teks, a 2246a 100mhz 2 channel, (i call it 2 because even though it has 4, only two are adjustable), and a tek type 422 15mhz. out of the two, i use the 422 the most.
     
  10. thakid87

    Thread Starter Active Member

    May 23, 2009
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  11. bill l

    Member

    Oct 11, 2009
    30
    0
    0-20v with 3a max output....to low for me.

    i use an atx power supply from an old desktop for my 12 volt needs for the moment.
     
  12. thakid87

    Thread Starter Active Member

    May 23, 2009
    122
    0
    Hmmm. Now I got something else to think about. If I'm going to spend money on this stuff, what would be a decent enough range to go for?

    0-30VDC? And 5 amps? More?

    Should I invest in a double output power supply?

    The last post put some doubt in my mind...
     
  13. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    I bought an HP E3615A on ebay a number of years ago for $100 delivered (I was the only bidder). It was in new condition and I think it was an outstanding deal. It is the most used piece of equipment on my bench next to my Fluke DMM. I have other power supplies, such as another HP supply that can put out 10 A at 60 V, and I need it occasionally when 3 A isn't enough current.

    If you plan on building circuitry, I'd recommend the typical 5 volt, ±20 volt triple output type of supply, as you can supply both analog and digital circuitry.

    I prefer supplies that are both constant voltage and constant current, which is why I don't have the triple output kind. However, a nice supply that can do both types of operations is the B&K 9130, but it's pretty pricey for a hobbyist.
     
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