[time-nuts] Rare HP clock
cfharris at erols.com
Mon Oct 3 13:04:03 EDT 2016
I have one of those, only in light gray.
It works quite nicely, though it is obscenely loud!
It has a divider network that takes 100KHz from a
companion reference unit, and divides it down to 1KHz,
that it uses to drive a stepper motor used as a synchronous
motor. The motor drives the mechanical counter mechanism.
Because the motor is being driven with a single phase
1KHz signal, you have to give its shaft a spin to start
There is a little crank driven synchro generator that
is used to insert a phase difference into the 100KHz
reference signal that serves to shift the edge of the
It is built into a cast aluminum chassis, that is sealed
with O-rings, and even has a humidity monitor to show
the condition of the air in the unit.
The biggest issues I can see with it are the strong
1KHz audio note, the condition of the ball bearings
that support the motor shaft, the little herd of
wet tantalum capacitors in its circuitry, and the
internal nicad pack that keeps it live during short
The mechanical counter probably needs some cleaning
and lubrication at this point.
Dave M wrote:
> It's Ebay item 351861979923
> Dave M
> KA2WEU--- via time-nuts wrote:
>> I can not find the item on EBAY , Ulrich
>> In a message dated 10/3/2016 11:51:24 A.M. Eastern Daylight Time,
>> jn6wfo at gmail.com writes:
>> According to my -hp- catalogs it was available only in rack-mount
>> form, not in a cabinet. That suggests it was being marketed to a
>> specific small group so it may indeed have been manufactured in
>> small quantities.
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