OT: HP70843B 12 GHz BERT info needed

Ed Breya

I posted this in the hpagilent group a while back, but no one seems to have info. That group seems pretty quiet lately, and I don't see indications that it's moved to groups.io yet. Since it's mostly the same folks in both groups, I thought I'd put it here for a bit where there's more traffic, and hope for some more visibility. Sorry that it's not Tek stuff, but it is highly related to fast pulse generators, which are near and dear to our hearts.

Anyway, here goes - it may be fun and useful to talk (some more) about fast pulsing technology, and GaAs devices, etc. I'd appreciate any info on this unit or its guts.

"I just picked up this beast for cheap, figuring there would be some fun microwave goodies inside. It seems to be a fairly obscure unit, with no info on the guts, and barely any about the unit itself. I found an operating and programming manual, and that's it. I've already parted it out and found lots of interesting stuff, including the four main source output modules, rated for tr and tf of about 30 pSec. These should be good for fast pulse generator work, but not unless I can figure out how to power them up and activate the control lines. The outputs apparently can run up to 12 GHz (or Gb/sec) data rate, up to a couple volts swing on 50 ohms. They appear to be some type of GaAs amplifier, so could be complicated making the biasing all work out right without any info or some reverse engineering of the support circuitry.

Does anyone know of any technical info on the innards? This is from the era of "No User Serviceable Parts Inside," and no manuals about the insides.

My plan is to put some of the sections back together enough to trace out the supply connections, and power up the pieces and see if I can get some of the items operational. I realize it would have been cool to use it in its complete form with lots of capability, but it would have taken lots of effort and more stuff to cable it up to a 70004 display, and maybe some SW, just to see if it worked. I'll be satisfied if I can get the output modules figured out and working. There's also a bunch of other microwave parts, and lots of EL-series "modern" high-speed ECL parts all over the place.

The SMPS is big - over 400W out I'd say, and I plan to use the whole carcass as a big multi-output supply after I figure out the modules and such. It has heavy -5.2V and -2 V, handy for ECL work, besides the usual +5V and +/-15V. There's room to add other supplies where the high speed pulse guts were, and plenty of cooling - six 3" fans pull air from one side, through the guts, and out the other side. Two are for the PS, and the others for the working guts up front."

That's what I wrote before. I've been studying it more and have some interesting observations that I'll report on later.


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