Opinion about HP 8903a Analyzer

[bear]

Ahhh, I see.

The main diff is lower noise floor in the analyzer, and balanced input... plus the onboard filter switches...

...which means different boards.

And, although I have not checked the manuals, I would be somewhat surprised if the E model used the same components as the B, but I suppose it is possible... older ICs get hard to source for new production.

_-_-bear

[bear]

Fwiw, and fyi, and pending any time to *actually do anything* I am acquiring some additional *boards* for the 8903A presently. Assuming I can get those that are doing the right stuff functional, then it may be possible to socket the ICs, look at the noise sources, improve the local regulation (hey there may be a real use for SMT? ) and try some newer ultra low distortion opamps in the holes...

yikes! another big project... phew.

(yeah, but I could be the 8903A hero?)

_-_-bear

[klewis]

@ Bear,
looking forward to what your results

[bear]

Looks like I have to print the entire manual to see what is going on, trying to look at this as an on screen pdf is fruitless.

_-_-bear

[Gavinator68]

How is the improvement of the 8903A coming along? Any progress?

Cheers

[bear]

Improvement? Ha! I have to get the first one I got off epay working!!
Thought I had it when I fixed an intermittent in the power supply - not!

I got one for parts cheap too... no time.



_-_-bear

[Gavinator68]

I just got mine from fedex this am and although it is an "A", i also got the K18 upgrade option from Tucker as well so it really is a "B" in an "A" chassis. Now I have a new input board, not that there was anything wrong with the original, but the new one upgrades the "A" to the "B" with differential inputs. So I got the "A" in great condition, the upgrade kit, and all three brand new HP bound manuals for 400.00 delivered.

Merry Christmas and Happy New Year to me!!!!

Cheers

[6L6]

Originally Posted by SY

Distortion analyzers are nice as an adjunct to a good soundcard/interface. If you don't have the latter, I'd get that before the analyzer;

Could you mention or link some examples? This is one of those things that people almost always talk about in generalities, and I am interested in actually getting something for the workbench -- I honestly have no idea what you guys are talking about.

The distortion analyzer will then allow you to visually examine the residual as well as use the spectrum analyzer to further break it down. A useful combination of reasonably inexpensive instruments gives you a lot of measurement power.

So would an older distortion analyzer, like the HP 339A, be useful?

And does any or all of this stuff measure IM distortion?

[bear]

There are some threads on soundcards here... I need a new one myself.

The better new ones no only do 24bit/192kHz. but they do it nicely with low residual noise and meet the max spec. But honestly even an average modern 24/192 card is probably going to be pretty good unless ur getting really into some cutting edge low distortion designs...

So you take ur signal, be it from the analyzer output (it has one) or direct from the DUT, and build a "signal conditioning" box so you don't fry the input of your soundcard (limited voltage input range) and then run a FFT type software to get a graph of the amplitude vs. frequency, that shows your fundamental and all the harmonics.

IM is two tone.

Some analyzers come with two tone testing.

I personally do not know if the 339A or similar is really terribly useful for this. However, with a Cordell Distortion Magnifier box, it well could be pretty darn good. (that is documented either here and/or online)

Crazy stuff...

[klewis]

The last 50 pages of low distortion audio range oscillator have dug pretty deeply into capabilities and significant modifications-improvements of the 339. It's in the equip & tool sub-catagory