[time-nuts] 5370A

[John Miles]

> I plan on doing the A3/A4 adjustments. I just don't know where I'm
> going to get a pulse generator or the fancy scope with the 1GHz
> sampling plugin. Not the type of equipment on your average test bench.

You won't need any exotic gear for the DAC voltage adjustments or the A3/A4
input assembly adjustments, which is what comes first in the manual.  As I
recall the scope is only used for symmetry adjustments in that section of
the manual, so the risetime is not all that important as long as it will
give you a stable trigger.

You can skip the pulse-response adjustment unless you have reason to suspect
a specific problem.  Watch for the pots that this step calls for, and don't
center them at the beginning of the alignment process when the manual tells
you to.  As I recall there are various typos in the manual, so watch out for
that too. :)  In general, the 5370 alignment instructions are crap by HP's
usual standards, so *be careful*.  Read and understand everything before
doing anything.

The A18 DAC adjustments should actually be done first IMHO.  Don't worry if
the test limit voltages are not achievable -- they aren't, on any 'B' model
I've ever aligned -- as long as they are symmetrical.  For example, +/- 1.9
volts is OK, instead of the +/- 2.2 volts called for in some versions of the
manual.

If you don't have an 8082A pulse generator and a fast scope, you will want
to stop there, and not mess with A19/A20.  Likewise you probably do not need
to align the A21 multiplier (which is the only step that requires a spectrum
analyzer) if you don't have reason to suspect a problem with it.  I believe
some people have found that the standard-deviation floor can be improved by
realigning A21 but I haven't done that myself.

The instructions that call for a 1 GHz sampling scope don't actually need a
sampling scope; they can be followed with a Tek 2467-class scope as well.
But again, the front-end work should be doable with a good 100 MHz+ model,
and the rest should not be attempted without an 8082A pulse generator.

The nasty thing about aligning a 5370 is the fact that the steps generally
begin with setting all the pots and trimmers to a fixed position, usually
midpoint.  Ordinarily it's best not to disturb the alignment of a stage
that's already in tolerance, but they don't give you that option with the
5370, and you may get pretty far before you discover that your test
equipment such as the pulse generator is not up to the task.  When they call
for an 8082A in the A19/A20 section, they *mean* an 8082A, and you don't
want to get halfway into that procedure before you realize that.

-- john, KE5FX