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

[David]

The AD1861 is very similar to the PCM61.  Both have plus and minus 3
volt output range.  They may be effectively interchangeable. 

Dave WA8YWQ 

On 2022-09-01 14:52, David G. McGaw via time-nuts wrote:

> 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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