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

[Jim Muehlberg]

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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