[time-nuts] Re: HP 10811A unusual appearance

[Brooke Clarke]

Hi Tom:

Interesting comment about flex circuits. Fig 2 in the HPJ article 1981-03 shows components on the flex. I see flex 
circuits in a lot of  military hardware but they are used to replace cables, not hold circuit elements.  For example:
PSC-2 Digital Communications Terminal (DCT)
https://prc68.com/I/Images/PSC2-13b.jpg

-- 
Have Fun,

Brooke Clarke
https://www.PRC68.com
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.

-------- Original Message --------
> Hi Adrian, Rick, Bob,
>
> The "flex" board is a thin ribbon-like PCB. It's shown in the manual [1] and described in the HPJ article [2], pages 
> 26-28.
>
> Jack Kusters (1937-2012) -- of SC-cut, 10811, 5071A, and GPSDO SmartClock fame -- once told me the flex board seemed 
> clever at first but was prone to fail when used in instruments on [military] aircraft due to prolonged exposure to 
> vibration. Or something like that. I'm not sure if that anecdote is related to the question here. I too would like to 
> see a tear-down of the two oscillators mentioned.
>
> /tvb
>
> [1] 10811A/B Oscillator Operating & Service Manual:
>
> http://hparchive.com/Manuals/HP-10811AB-Manual.pdf
> http://leapsecond.com/museum/10811a/10811a.pdf
>
> [2] Hewlett Packard Journal, March 1981:
>
> https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1981-03.pdf
> https://archive.org/details/Hewlett-Packard_Journal_Vol._32_No._3_1981-03_Hewlett-Packard
>
>
> On 8/24/2022 1:24 PM, Adrian Godwin wrote:
>> If it's not too off-topic, what is a 'sculptured' flex circuit ?
>> The 10811 I've taken apart has a 2D-shaped and folded flex circuit that I'd consider 'conventional' - does a 
>> sculptured one have some integral 3D shaping ?
>>
>>
>> On Wed, Aug 24, 2022 at 7:46 PM Bob kb8tq via time-nuts <time-nuts at lists.febo.com <mailto:time-nuts at lists.febo.com>> 
>> wrote:
>>
>> Â Â Â  Hi
>>
>> Â Â Â  I should have access to the supply dump some time in November.
>> Â Â Â  My take was that they started off with a more exotic PCB approach
>> Â Â Â  early on and simplified things a few years later. If I remember
>> Â Â Â  correctly
>> Â Â Â  the solder mask changed a bit at the change over as well.
>>
>> Â Â Â  Bob
>>
>> Â Â Â  > On Aug 24, 2022, at 6:13 AM, Matt Huszagh <huszaghmatt at gmail.com
>> Â Â Â  <mailto:huszaghmatt at gmail.com>> wrote:
>> Â Â Â  >
>> Â Â Â  > Bob kb8tq <kb8tq at n1k.org <mailto:kb8tq at n1k.org>> writes:
>> Â Â Â  >
>>     >> There are at least two *very* different 10811 PCB’s out in the wild
>>     >> in quantity. I don’t have access to the “stockpile” right now
>>     so I can’t
>> Â Â Â  >> say how the one in the picture compares to the commonly seen
>> Â Â Â  >> varieties.
>> Â Â Â  >
>> Â Â Â  > If you do get access at some point and it's not too much trouble to
>> Â Â Â  > check, I'd be interested to know more about this. Do you know
>> Â Â Â  the reason
>> Â Â Â  > for having two versions? Is it simply that one was an earlier
>> Â Â Â  design and
>> Â Â Â  > the other replaced it?
>> Â Â Â  >
>> Â Â Â  > Thanks
>> Â Â Â  > Matt
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