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

[Bob Camp]

Hi

The 10811 on that plot would go in the “broken” pile if I was doing a sort. I suspect there is something
wrong with it internally. Just what …. who knows.

Bob

> On Sep 1, 2023, at 9:19 AM, Jim Muehlberg via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> One day, I'll figure out the attachment protocol on this list!...
> 
> PN plot and manual section attached, I hope.
> 
> Jim
> 
> On 2023-08-31 10:13 AM, Jim Muehlberg via time-nuts wrote:
>> 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
> P 434.296.0270
> C 434.422.2017
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