EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: BillWojo on July 30, 2014, 02:11:45 am
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Slowly putting together a electronics repair lab. I repair machine tools for a living so that means I do some CNC repair along with general electrical repair. Plus a lot of mechanical repairs, that has always been my strong point. Picked up a lathe for personal use and it has a DC drive with thyratron tubes, that prompted me picking up a Tektronic 465M scope to troubleshoot the drive. Last week I picked up an old Hammarlund ham radio, dead as a doorknob. Filaments light but no output. So I want to pick up a AF and RF frequency generator. After troubleshooting it I'm going to want to tune it up. Other equipment that I have is a Fluke 179 and a Simpson 260 meter, just bought a Fluke 1900A frequency counter and a Data Precision 938 cap tester. Also have a Power Designs 6050 power supply and a few meggers.
So I'm looking for a used, not expensive AF generator suitable for radio work and a RF generator. I have been reading up in the ham forums but am still a bit confused on what I really need to get. I have a lead on a HP8116A function generator but I'm not sure that it will do what I want. Plus who knows where this will lead me down the road. So what do you guys suggest?
Thanks
BillWojo
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Good memories. We studied thyratron motor controllers in my first electronics classes back in the early 70s.
It sounds like you're off to a good start with your test equipment. The HP8116A is a very nice function generator that works up to 50MHz, but it doesn't generate pure sine waves so you'll also want a stable RF frequency generator.
Since a drifting signal generator is just about worthless, I'd avoid the cheap ones.
Decent tube type RF generators include the military URM-25 (HF) and URM-26 (VHF) or the HP 606 (HF) or 608 (VHF/UHF). The analog HP8640B is good if you can find one that works, but parts are hard to find. Synthesized generators include the Wavetek 2407/3000/3001, Fluke 6080A, HP 8656B, and Marconi 2018/2019, 2018A/2019A and 2022 series.
An older communications service monitor makes a nice "everything in one box" addition to a bench, but the drawback is that they don't do any one thing as well as dedicated equipment. Examples are the Wavetek/SSI 3000, IFR-500/1000/1200, Motorola 1200/2001/2200/2500/2600 series, Cushman CE series, etc. I have a Wavetek/SSI 3000 and an IFR-1200S that I use quite often, but I do a lot of radio work.
Someone else will know more than I do about what is current from Rigol and other vendors and may have better suggestions.
Bob
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I would think a lot depends on how much money you want/have to spend, I started with an old HP 3314A for a freq gen and HP 8656A for RF. For me the ability to synch to a 10MHz reference source is important and so I got a Agilent 33519B recently.
I use it for mainly Ham work, for higher RF (2-25GHz) I use usually direct synthesisers ( e.g. from Down East Microwave, Kuhne, home brew etc) as the Ham bands are quite limited so I don't need an RF synthesiser that can cover all the bits in-between.
Here in Australia, crazy postage costs limit purchase of US second hand gear but we are getting some bargains out of Hong Kong & China if you are a bit brave.
I am a HP Agilent fan and have had a good run with their gear, I would tend to stick with them.
Edit PS Some of the mid-range Rigol stuff seems to be "behaving" nicely i.e. not a lot of quality issues and for good priced new gear my be worth a look as well.
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For your current needs I would recommend an old Marconi TF 2016 (LF to 120MHz) as it has the right balance of low cost, small size, easy maintenance and nice touchy/feely user interface and minimal frequency drift when warm.
However, if you want something newer that is synthesised then I guess the little Marconi 2022 would be a step up in performance but you lose the touchy/feely interface as it has no rotary controls.
Note: if you want to tinker inside old boatanchor valve radios I'd recommend you make a decent dc block/bleed to protect your signal generator. Something rated to 1kV would be a reasonable spec.
You could use a soundcard for an AF generator but you face the same risk of exposing it to high voltages. You could use an AF isolation transformer but I'd be tempted to try using a basic old school function generator and a decent dc block/bleed/limiter.
Obviously, with high voltage vintage gear you also need to set up your work bench to be as safe as possible and you need to be careful of earth discharge paths (through YOU) to earth via your test gear. But I guess you know this already...
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Nice suggestions but I'm not looking to spend a lot on this test gear. Doesn't make sense to invest to much for a $10 ham radio that I'm not even sure will work.
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I own a HP 8116A and the performance is terrible compared to newer models (oh well, mine was free). The one at work has the same issues. We measured up to about 3% in frequency deviation on a 10khz signal over a 24 hr span. Amplitude wasn't very stable too.
Besides that it's noisy and physicaly very long.
But for most testing purposes it wil do ok.
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Nice suggestions but I'm not looking to spend a lot on this test gear. Doesn't make sense to invest to much for a $10 ham radio that I'm not even sure will work.
If it's mainly for repairing/aligning that old Hammarlund and you've already got a scope & frequency counter, then grab an old Leader LSG-16 or similar for cheap. Or Google around and build one; it's probably even cheaper.
Yup, crap by modern standards - but it's still 10x better than anything a radio tech would've had back when that Hammarlund was built...