[time-nuts] Re: Oncore UT+

[Bob kb8tq]

Hi

The original Oncore modules are all a bit past their practical “use by” 
date. Even if you *can* find one, issues are likely to crop up. Better to
shop around for one of the modern drop in replacement parts. 

The disadvantage of this approach is that the price of one of the modern
parts might be a signifiant fraction of the cost ( < $100 delivered)  of an 
eBay GPSDO. 

Bob

> On Nov 15, 2022, at 6:28 AM, alan bain via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Hello all,
> 
> I'm sure I'm not a time nut. But in the beginning I had an HP5245L and its
> oven oscillator defined 10MHz in my corner of the world. Unfortunately one
> day the oven heater stopped working.  And sadly HP didn't include an oven
> temp stable indicator. So things started to go wrong when aligning a
> spectrum analyser (somewhere in the GHz region where that 10MHz had been
> multiplied up a lot).  As one might expect crystals designed to be stable
> at 70 degrees C have a large temp-co at room temp.
> 
> A kind loan of an off air (Drotiwich) standard and HP53131A enabled some
> element of normality to be obtained (and the oven fault to be found and
> fixed) - interesting to see the HP200 style thermistor limited  oscillator
> followed by envelope detector used as a temperature controller!  But of
> course I was curious as to how the various oven oscillators in test gear I
> owned actually behaved (such is the danger of having done a PhD in
> stochastic processes). It's nice also to find non-Gaussian noise processes
> cropping up along with the two sample variance.
> 
> A better reference was clearly needed. To convince myself I don't need a
> Caesium standard I decided I needed a GPSDO.  I've been modifying one of
> those Lucent RTFG-u REF-0 boxes following Peter Garde's excellent
> instructions (because it looked fun).  All was going well until i found my
> Motorola Oncore module believed to be a UT+ when bought was in fact a GT+
> and didn't provide some of the T-RAIM messages the HP needs (the GT+ is a
> navigation receiver).
> 
> There's not much info around on these modules (probably because they are
> ancient) - and at the moment no UT+ listed anywhere in the UK for sale; so
> wondering if anyone knows about the differences - are they firmware or
> hardware?  There's a firmware upload option in the WinOncore software - but
> I haven't been able to find any archives of the actual firmware.
> 
> Alan
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