[time-nuts] HP 106B quartz frequency standard...the story so far

John Miles jmiles at pop.net
Sat Aug 8 17:29:36 UTC 2009


If it's an older germanium PNP pass transistor then yes, rest assured, it is
leaky and needs to be replaced with a modern silicon part.  Germanium power
transistors don't age well.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of WB6BNQ
> Sent: Saturday, August 08, 2009 5:07 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] HP 106B quartz frequency standard...the story
> so far
>
>
>
>
> And one more request, please measure and tell me what the values are for
> the base of the pass element and any driver transistor connections.
>
> Also, it may be that the power supply is really a current source for
> charging the batteries.  The power supply and the instrument may need
> the batteries to work correctly.  Hp was famous for this type of circuit
> topology.
>
> Bill....WB6BNQ
>
> Hi Jim,
>
> YES, please email me the schematics.
>
> thank you
>
> Bill....WB6BNQ
> wb6bnq at cox.net
>
> Jim Palfreyman wrote:
>
> > OK folks, I've rechecked the voltages and here's the details.
> >
> > Firstly, changing the oven temperature screw was a mistake. Read a
> > previous thread to see why I did it. It was logical given my
> > experience with 10811 ovens. I've owned up to it and begged
> > forgiveness from the great Flying Spaghetti Monster. It never answered
> > so it must have made me do it. Please drop that now. :-)
> >
> > When I first powered the unit up it had bad and leaking NiCd batteries
> > and made a horrible sound. I removed those and I presume something was
> > damaged.
> >
> > The "input" voltage to the 2N1701 is normal (according to the front
> > panel meter) and is close to 26V. The "output" voltage is 25V and not
> > 18V as the manual says. I have the manual now and anyone (with more
> > experience than me on old fashioned power supplies) who wants to
> > comment I am happy to email the circuit diagram and eagerly await
> > comment!!!
> >
> > Jim
> >
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