[time-nuts] New NTBW50AA

Bob Camp lists at rtty.us
Tue Sep 10 07:30:21 EDT 2013


Hi

Your temperature plots look like mine. I suspect the other unit has a broken temperature detection chip. I've seen that happen on TBolts.

Bob

On Sep 9, 2013, at 10:44 PM, Arthur Dent <golgarfrincham at yahoo.com> wrote:

> I have a slightly earlier version, or a close cousin, of the NTBW50AA that 
> I modified and I've posted photos of it on this list before: 
> http://i906.photobucket.com/albums/ac262/rjb1998/NTPB15AA05.jpg
> 
> The LH plot from the NTBW50AA by quartz55 doesn't look quite right. Here 
> is a LH plot from my NTPB15AA  unit with most of the scale factors set the 
> same as the scale factor in the plot from the NTBW50AA to make it easier 
> to compare. 
> http://i906.photobucket.com/albums/ac262/rjb1998/NTPB15A_zps19b3bd33.jpg
> 
> If you look at the temp plot from my unit it has small steps and is what I'd 
> expect to see. The plot from the NTBW50AA looks like it has some smaller 
> steps but it looks like it hits a limit at 36.750 and doesn't go beyond that 
> value, which isn't right. It looks like a higher order bit is being turned on 
> and off randomly causing the large apparent jump in temp, which 
> probably isn't really happening because some of the other traces would 
> be affected by any real jump that large. You could just ignore it because it 
> would probably only have an effect during carryover. 
> 
> The NTBW50AA oscillator  probably hasn't settled down yet because the 
> DAC voltage is changing a lot more than mine and the 10Mhz doesn't look 
> anywhere near as stable. The design of the 2 units appears nearly identical 
> so I'd expect similar performance. Also the OSC ADEV at 10000 tau isn't close 
> to what mine appears to be. That may improve after the unit has been on
> for a month or so but the temp plot just doesn't look right so the sensor may
> be bad.
> 
> -Arthur 
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