[time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

[Orin Eman]

FWIW Re: the relays.  I worked through the Omron discontinuation notices
for the first relay (I figure the original was a G5Y series, not GSY as in
the manual) and it looks like the G6K series, easily available at Mouser
and about $4 each would work, though you'd have to use a DPDT.

The other two relays are cute little TO5 relays from Teledyne - 412 or 712
series, 12V coil.  The 712-12 will cost $35 at Mouser.  Ouch.

>From reading the paper and the Basic program, the _critical_ part of the
circuit is getting the delays with the outputs swapped exactly the same as
the delays with the outputs unswapped.  A non-trivial task since the traces
are all 50 ohm stripline.  (Or so the manual says - a picture of both sides
of the original PCB would help immensely in determining how critical the
layout is.)

(Phase differences due to the splitters are eliminated by taking a reading
with the outputs unswapped, then with the outputs swapped.  Taking half the
sum of these two readings eliminates the phase error due to the splitter.
At least that's what the Basic program does; the description in the paper
is slightly different, but the equation simplifies to the same thing.)