[time-nuts] Re: HP 115BR Clock 60 Hz output option

[Jeremy Nichols]

Early HP (and other?) frequency standards generated frequency sub-multiples
using either regenerative or phantastron dividers. Regenerative dividers
are used primarily because they are NOT self starting. If anything
interrupts the circuit, the outputs stop, signaling the operator that the
clock is now in error.

Phantastron divide-by-10 circuits work by summing pulses, the circuit being
constructed so that 10 pulses into the phantastron yields one pulse out.
The circuits typically contain adjustable elements allowing the operator to
‘tune’ the circuit for 9, 10, or 11 pulses. It would be easy (he says!) to
modify such a circuit to sum 6 pulses instead of 10, before triggering an
output pulse. That would get you 60 Hz instead of 100 Hz, for example.



On Tue, Mar 7, 2023 at 9:20 AM John Vendely via time-nuts <
time-nuts at lists.febo.com> wrote:

> Hi Jeremy,
>
> Thanks for the reply.  If nothing else, I'm curious to see how HP
> accomplished the 60 cycle output option.  Though trivial today,
> synthesizing 60 cycles from the frequencies available in the 115BR
> wasn't so convenient back then, given the primarily analog and
> rudimentary digital methods available at the time...
>
> 73,
>
> John K9WT
>
> On 3/6/2023 7:24 PM, Jeremy Nichols via time-nuts wrote:
> > Sorry I can’t contribute here. My 113AR does not have a 60 Hz output
> > option, which could be convenient for running a standard clock. The
> outputs
> > of my 113AR are half a volt, approximately. A 60 mV output does sound on
> > the low side.
> >
> > Possibly tvb (Tom Van Baak) will see your message and respond. He has a
> 115
> > and probably the manual too, although I don’t know if his 115 has the
> > option of a 60 Hz output.
> >
> > Jeremy
> > N6WFO
> >
> >
> >
> > On Mon, Mar 6, 2023 at 4:22 AM John Vendely via time-nuts <
> > time-nuts at lists.febo.com> wrote:
> >
> >> The HP 115BR clock was available with an optional 60 Hz output. The
> >> service manual mentions the option but provides no schematic. My 115BR
> >> has the 60 Hz output option (a front-panel placard reads "Specif. H08
> >> 115R), and after running it for over 30 years, I'm finally getting
> >> around to using it to drive a synchronous motor clock via a small
> >> class-D power amp and step-up transformer. However, the 60 Hz output
> >> level is very low, around 60 mV p-p, and somewhat distorted.  I doubt HP
> >> designed it that way.  Before going to the trouble of
> >> reverse-engineering it, I thought I'd check to see if anyone has seen a
> >> schematic or other information on this option?
> >>
> >> Many Thanks,
> >>
> >> John
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-- 
Jeremy Nichols
Sent from my iPad 6.