[time-nuts] Re: info on the 10811 used in the HP5071A {External}

[Jim Muehlberg]

I've got a 10811-60101 (1982 SerNo) (No A/B/D/E suffix) kicking around 
the lab from a scrapped HP8673B that I thought was broken when I 
measured it's phase noise: (Top Trace).

10 MHz Oscillators

I found this:


Curious as to why HP would put an "unspecified" oscillator into one of 
their signal generators!? (esp Phase Noise!)

Jim

On 2023-08-30 8:11 PM, Richard (Rick) Karlquist via time-nuts wrote:
> I had forgotten the details.  The schematic is indeed changed
> because the trimmer is now in series with the varactor.  That
> is definitely something I would do; I never approved of the
> trimmer being in parallel with the varactor.  And the MVAM125
> is one of my favorites.  Definitely, I am the one to get
> credit or blame for this :-).  It must have "just worked"
> as I like to say, because I never heard about it again.
>
> OTOH, I have never seen a complete 10811 schematic with this
> circuit.  I still don't remember having to modify the PCB/flex
> circuit for this.  I am thinking they just kluged it onto the
> regular one.  We would want to manufacture standard 10811's
> from which ones intended for the 5071A could be selected.  Then
> they would be modified with the circuit you showed.  There is
> probably a drawing somewhere showing where to cut traces and
> how to install jumpers to complete the rework.  Almost any
> section of the 5071A, beginning with the CBT is total rocket
> science compared to the tuning rework; and we only sold something
> like 10 a month in those days.
>
> I didn't know about the "wavy" ("Belleville") washers, but I
> totally approve.  That sounds like something Len Cutler
> would have insisted on (if so, good for him).
>
> Rick N6RK
>
> On 8/30/2023 1:40 PM, Corby Dawson via time-nuts wrote:
>> Here is an old post showing the schematic changes required for the 10811
>> oscillator modified to the 05071-60219.
>>
>> https://febo.com/pipermail/time-nuts_lists.febo.com/2018-January/090824.h 
>>
>> tml
>>
>> Cheers,
>>
>> Corby
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-- 

Jim Muehlberg
Senior Engineer

National Radio Astronomy Observatory
ngVLA Local Oscillator Lead

1180 Boxwood Estates Rd B-111
Charlottesville, VA 22903-4602
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C 434.422.2017