[time-nuts] Input filter for data logger

Neil neil at g4dbn.uk
Sun Nov 19 18:19:27 EST 2017

I have four MV89As.  Two are excellent and run at a case temp around 
43C/110F.  One tends to jump frequency when you move it, it also sits 
around 43C/110F  though. The final one has a broken temp controller.  
Mounted inside a large block of expanded polstyrene insulation, it 
reached 92C/198F before I realised something was not right.

The best MV89A has been running continuously for 18 months and has 
drifted LF by 1.2ppb in that time, compared with two GPSDOs and the 
GB3MHZ GPS-locked beacon on 1296.830MHz

The two bad ones were cheap and were still soldered to bits of hacksawed 


On 19/11/2017 22:56, Angus wrote:
> On Sun, 19 Nov 2017 16:10:54 -0500, you wrote:
>>> The MV89 is a beast of an OCXO and uses more power at warm-up than any
>>> other
>>> I know of. But it is spec'ed ~1W for steady state. Which means the
>>> outside of the OCXO should be about hand-warm. If it's too hot, then
>>> the heater circuit is probably broken and running at full-throttle.
>> If so, I think something is not OK with my MV89. It is probably 110
>> degrees or so.
> They do run hot, so if that's 110 DegF and not DegC it's OK (depending
> on ambient...) The data sheet says 4.2W at 25 DegC.
> BTW if anyone is thinking of visiting www.morion.com.ru this might not
> be a good day - when I tried earlier the AV claimed it was infected
> and the script blocker went nuts, so they did seem to have got
> infected by something.

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