HP Signal Generators on E*bay

out..

Be aware that the knob on the A33250 is used to increment/decrement the selected parameter (frequency or amplitude) digitally. You can select the digit in the display that it modifies, so for example you can step in 1 MHz steps, 100kHz steps, ... 1Hz steps, ... 0.001Hz steps... (I think it goes that low...) It's not the same as an old- fashioned knob controlling a variable capacitor or resistor with "infinite" resolution. That's not to say it's inferior; it's just different and takes a bit of getting used to if you haven't used other equipment that operates similarly. But all my HP/Agilent gear works about the same in this regard. Note: if you select the amplitude display in dBm, the knob modifies dBm. If you select the amplitude in volts, the knob modifies volts. Though the 3325 lacks a knob, it does let you modify digits. In the "modify" group of four buttons, you can go up and down by pressing an ^ or v button, and select which digit to modify by pressing the < or > button. The effect is the similar to using the knob--sometimes more convenient, sometimes less.

Though the HP3325A is a good generator, it does have some limits. I recall wanting to use it to in essence divide a frequency down for a digital application; I could set up two 3325A generators running from the same reference and select output frequencies in the ratio I wanted. But I discovered that the jitter or phase noise of the outputs relative to each other was not terribly good. I have the impression that the 33250 uses a direct digital synthesis scheme, which should have much better phase noise.

Cheers, Tom

You certainly make the Wavetek generators sound like boat anchors. Big. Heavy.. Worn out... And gets tossed overboard. :P

D from BC British Columbia Canada.

Don't forget to add concrete, so no one can drag them back to the surface. :(

--
Service to my country? Been there, Done that, and I\'ve got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

I confess to getting a lot of use out of a couple of old Wavetek 145 Pulse/Function generators that I picked up for about $50 each. They have lots of useful inputs, outputs, and knob controls and lots of output amplitude and DC offset adjustment, and they take up a lot less bench space than HP3325s (which I also have). I've cycled a half dozen

145s through my lab. They often have one of the output transistors shorted, but that's an easy repair job. Just don't expect low distortion or particularly fast rise and fall times. Many pieces of older test gear, including HP, will be in need of some lube and contact cleaning work. Caig Lube seems about the best product for that. Paul Mathews

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I'd like to add that recently for HP 3325A: Price E*bay Item number $407 190198690637 $259 320216764947 Active 200200995997

I'm guessing basic supply and demand. I haven't looked at generators, but I occasionally watch oscilloscopes on the bay.

It seems there's always a preferred "scope du jour" that has been dumped on the market in large quantities by military or industrial outlets. If that particular scope meets your needs, you're in luck, because the flood of them has made them a good value.

Maybe you're seeing the same thing for generators.

Tom

$250

With a DDS eval board, do you get a stand-along instrument that's rugged, has full front-panel control of all functions, can output 10V into 50 ohms, looks like a good clean 50 ohms source, has accurate output amplitude control done in a way that the signal quality isn't degraded at low output amplitudes, whose output can include a DC offset, whose output can float up to 40 volts from ground, can output sine, square or triangle, outputs a sync pulse with settable phase relative to the output waveform, can do frequency sweeps without any additional software, ... Need I go on??

I suspect it's more a supply-vs-demand-vs-perceived-value thing. Though old, the 3325 is still a decent, reliable generator. Given a choice between a free HP3325 and a free AD9852 eval board I'd for sure pick the HP3325, because my vision would be to use it as a general purpose instrument on my bench. Given a choice between a free HP3325 and a free Agilent PSG, I'd for sure pick the PSG, not just because it's a lot more expensive instrument, but also because it generates signals more in line with what I use on a regular basis. Get the generator that fits your budget AND does the work you want reliably enough for your application.

Cheers, Tom

I confess to getting a lot of use out of a couple of old Wavetek 145 Pulse/Function generators that I picked up for about $50 each. They have lots of useful inputs, outputs, and knob controls and lots of output amplitude and DC offset adjustment, and they take up a lot less bench space than HP3325s (which I also have). I've cycled a half dozen

145s through my lab. They often have one of the output transistors shorted, but that's an easy repair job. Just don't expect low distortion or particularly fast rise and fall times. Many pieces of older test gear, including HP, will be in need of some lube and contact cleaning work. Caig Lube seems about the best product for that. Paul Mathews

I've the 20MHz, 30Vpp 145 and the 164 that'll do 20Vpp to 30MHz. UK wise the Wavetek stuff seems as hard to come by as rocking horse s*** and although I paid about $90 each I've found 'em indispensable and worth every penny. Horses for courses, I'm not wanting frequency and amplitude precision in the ppm area, or rise times any better than 20nS, or crappy GPIB, or plasma displays, or networking, or internet connectivity or any of the other 'must have' fluff that people seem to want to pay lots of money for. At the moment they're earning their keep simulating frequency dither on a particular 50Hz site generator. Yep, oodles and oodles of knobs to twiddle and switches to switch. Took about 10 minutes to set up and tweak. Hate to think of trying to key that lot into some expensive digital units.

"scope du jour" :)

D from BC British Columbia Canada.

$250

Cool.. :) Thanks for clarifying the DDS performance. I might get a AD9852 Eval board someday.

D from BC British Columbia Canada.