[time-nuts] 10811 warmup

[Jack Hudler]

http://www.hpl.hp.com/techreports/1999/HPL-1999-6.pdf

See page 2

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf
Of Rick Karlquist
Sent: Sunday, January 21, 2007 9:40 PM
To: Discussion of precise time and frequency measurement
Cc: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 10811 warmup

The oscillator is derived from a conventional Colpitts
circuit, with a capacitor from base to emitter, a
capacitor from collector to emitter, and the crystal
(in parallel resonance mode acting as an inductor) from
the collector to the base.  This is referred to as a
Pierce oscillator.

The desired mode of oscillation is mode C.  However, mode
B (with high tempco) has more gain, and a means for
preventing mode B oscillation is necessary.  There is
a network with 2 capacitors and 2 inductors (IIRC) from the
base to the emitter.  At 10 MHz, this looks capacitive
and serves as the capacitor in the conventional circuit.
At 10.9 MHz (IIRC) where mode B is, this network looks
like some other impedance, which in any event, does not
permit oscillation.

The crystal goes from the base to ground in conjunction with
the EFC circuit, however "ground" is the very low input
impedance of a common base amplifier.  The collector of the
transistor is RF grounded.  Thus the crystal is effectively
from collector to base.

The grounded base amplifier reduces far out phase noise as
taught in Burgoon's patent.

I can assure you that Burgoon knew exactly what he was doing
and even if it looks bizarre, there is very solid engineering
behind it.

Rick Karlquist N6RK


Normand Martel wrote:
> It's bizarre..
>
> The oscillator is some kind of Colpitts but with coils
> instead of capacitors in the feedback path.
>
> (i don't call it a Hartley, bcause Hartley's use a
> SINGLE tapped inductor.)
>
> 73 de Normand VE2UM
>
> --- Dr Bruce Griffiths <bruce.griffiths at xtra.co.nz>
> wrote:
>
>> Hal Murray wrote:
>> >> Is it okay to power up the main assembly once it
>> is removed from the
>> >> outer shell / insulation?
>> >>
>> >
>> > Lots of info here:
>> >
>>
> http://www.hparchive.com/Manuals/HP-10811AB-Manual.pdf
>> >
>> > I think I saw a warning about that, but maybe it
>> was something else.
>> >
>> >
>> >
>> It is OK to power up the oscillator and output
>> amplifier, but the oven
>> circuit should not be powered up.
>>
>> Bruce
>>
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