Re: OT: HP70843B 12 GHz BERT info needed

Jim Ford

Hi, Ed.

I'm forwarding your message to another Ed I know who may know something
about this beast. I envy you for finding it!


------ Original Message ------
From: "Ed Breya via Groups.Io" <>
Sent: 7/21/2018 10:53:01 AM
Subject: [TekScopes] OT: HP70843B 12 GHz BERT info needed

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 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

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

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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