[time-nuts] Re: James Miller/Brooks Shera 10 MHz GPSDO

[David G. McGaw]

I have one of the double oven 10811s and there is no tuning hole in the 
inner case.  One would have to remove the flex-circuit outer oven 
heating element and open the inner case to get to the tuning cap.

I do not find a schematic of the Brooks Shera board that uses an 
AD1861.  If there is one, perhaps we could rework the circuit to have 
bipolar output.

David N1HAC

On 9/1/22 3:36 AM, Mervyn Thomas via time-nuts wrote:
> Dan,
>
> As a last resort I would attempt to disassemble the osc.  What 
> concerns me is the picture of the osc. shown in the article you gave 
> is not my version osc. so I'm pretty sure there would be no tuneable 
> cap inside mine??  Will keep the group posted on results.
>
> Merv
>
> On 30/08/2022 8:25 pm, Dan Kemppainen via time-nuts wrote:
>> I found this helpful long ago...
>> https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.realhamradio.com%2FGPS-oven-journey.htm&data=05%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7C4cec14fbc44e4985d4c608da8c548d5d%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C637976592033788783%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=atgiKtTy8I1x3y5Lm71YavmLdGeQ84dBgfyi1%2FCXjwM%3D&reserved=0 
>>
>>
>> I think you would only need to go part way in to get to the 
>> adjustment screw.
>>
>> The double oven was used in some equipment spec'd for cold climate 
>> operation. It helped speed warmup or some such issue. People have 
>> used the outer oven to help stabilize the temperature, although from 
>> what I understand that was not the original intention.
>>
>> Let us know what you find!
>>
>> Dan
>>
>>
>> On 8/30/2022 3:31 AM, time-nuts-request at lists.febo.com wrote:
>>> Unfortunately the HP 10811's I have are in a completely enclosed can 
>>> - no holes to poke anything through. To get at any tuning capacitor 
>>> would probably entail taking the insides out of the can.
>>>
>>> The oscillators like mine must have been fairly rare as I am unable 
>>> to find anything via Google.  They have 2 main power leads coming 
>>> out of the can with 6 pin female connectors to connect to the power 
>>> Power Board which is out of an HP Z3801 GPSDO and 2 thin coaxes with 
>>> SMB connectors on the end - one marked as 10MHz and the other as EFC.
>>>
>>> Regards,  Merv
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