[time-nuts] Re: Oscilloquartz 8663-XS stability problem

[Dan Rae]

On 10/27/2023 7:15 AM, Brian K via time-nuts wrote:
> I recently constructed a homebrew 10MHz distribution amp.
> It has provision for both an external 10MHz source such as a GPSDO or an internal OCXO.
> For the internal OCXO I chose a used Oscilloquartz 8663-XS from China.

Brian, Sorry to say I'm pretty sure you have a faulty OCXO.  I have used 
several of those and the control voltage to reach 10 MHz is usually 
around 5V, which can be easily achieved from the Reference V output, 
which is around 8V.  It looks to me like there is a fault in the 
oscillator circuit inside the inner oven.  Total control range should be 
at least 2 Hz either side of nominal.  I have one in my Shera GPSDO and 
over more than two years the control voltage has crept up very slowly 
due to ageing and shows a very slight diurnal variation due to room 
temperature changes.

And there's no trimmer inside, the solder blob was presumably when they 
filled it with whatever inert gas they used at manufacture.

Dan