Power Line Noise Infecting Instruments?

It's a 3582A and this is just the first hit I found on the model; haven't had time to read it through the spec yet. Got *way* too many boat anchors here; not even sure how many SAs I have in total.

Nope. All the stuff I keep is all single-purpose, stand-alone, dedicated kit (and none of that menu-driven crap, neither).

Nice. However, that's an FFT based low frequency spectrum analyzer. I can't seem to find the specs, but found it in the 1980 HP Test and Measurement book. Say nice things about me and I'll scan the pages for you if I can find my document scanner.

I stole this from somewhere:

The HP 3582A is a High-Resolution, Low-Frequency Dual Channel Spectrum Analyzer. The measuring bandwidth of the Model 3582A can be as narrow as 0.02 Hz in a 5-Hz frequency span anywhere in the 0.02-Hz-to-25.5-kHz range, and on the 0-to-l-Hz frequency span the bandwidth can be as narrow as 0.004 Hz. The instrument's dynamic range is more than 70 dB with full-scale ranges of +30 dBV down to -50 dBV ( + 30 V rms to 3 mV rms).

The Model 3582A Spectrum Analyzer uses digital processing with the fast Fourier transform (FFT) to derive a complete 256-line spectrum from just one input record, an especially important capability in an analyzer with very narrow band widths. For example, using the 0-1-Hz frequency span, Model 3582A takes 250 seconds to obtain a single time record from which it derives a spectrum with 0.004-Hz resolution. A swept-frequency spectrum analyzer would take over 100 times as long to obtain a spectrum with that resolution.

Looks good for vibration analysis and audio. No tracking generator. Manual is dated 1978. Selling price on eBay runs $200 to $1300:

Well, if you have any more spare spectrum analyzers laying around, just send them to the address below.

Ok, bad guess. Looking at the front panel at: The banana jacks are the Ch A and Ch B inputs.

Quick reference guide:

I never say anything *but* nice things about you, Jeff. I'm your biggest fan. Honest!

Sounds about right.

Wow. Well, if I ever need to examine a half-Herz signal to within 0.004 Hz resolution, I'll know which piece of equipment to use. Problem is I'm kind of thinking that'll never happen. In fact I can't even think why anyone would want to do that. But I have a hunch you're about to disabuse me of my ignorance on the matter.

Thanks, I'll check it out. But I have to say it's making a really effective door-stop right now and I have no plans to re-purpose it.

Done. See: I had a problem scanning it. The original is in a hard bound book format. It's impossible to flatten the page near the binding unless I tear apart the book or break the binding, which I'm not going to do. Using a camera photo didn't seem any better. Bug me if there's some part you can't read.

This SA was DOA when plugged in, which I view as a plus, since I'm hoping it's just a problem in the PSU section which I can sort out without needing a schematic. But I'm rarely if ever that lucky, so I'll save a copy of your scanning efforts (for which ta muchly) in the event it's something less straightforward.

Unless you are balanced using a Balan, chances are huge that you are measuring common mode noise between line and neutral by connecting between line and ground.

Care to share setup and results?

cheers Tony.

A new LED bulb caused the problem. All is well since I removed it. Would be interesting to know why a LED bulb would cause such a thing. I suspect some of you engineers would know it.

I got myself one of these:

which I can hook up to an analogue scope to examine how clean the power supply is. It's a damn sight cheaper than buying even more dedicated gear!

If it's anything like the CFL bulbs (currently being slowly discontinued here in Britain) it won't be the LEDs themselves but the driver circuitry the manufacturers incorporate inside the bulb housing. Ultra-cheap and nasty Chinese quality junk prone to partial if not complete failure.

I have had a lot of failures of a particular type of 12V LED. One recently only lasted 3 months. In every case the fault seems to be with the LED matrix and not the constant current controller.

Part of the array goes dark while another part gets over-bright. Then a different part gets dark and another part lights up brighter. It continues flickering like this for a few days before it dies completely.

The LED array is probably four (I would need to look again to be sure) strings of several LEDs in series in each string with all the strings in parallel. The LEDs are on a ceramic substrate covered in phosphor gel. I suspect bond wire detachment resulting from thermal stress.

The electronics board is very nicely made.

John

Ditto. Heavy, all the machined shielding.