[time-nuts] Re: Austron 1250A ADEV Hump

[Tom Van Baak]

Yes, monitor oven current. Or watch AC power consumption with those 
plug-in watt meter adapters. Or tape a thermometer to the oscillator, 
looking for telltale clues.

Back in the 90's when I entered the world of used test equipment my 
first purchase was a hp 5245L, the model I remembered using in Physics 
lab in the 70's. So for a time that was my only instrument and it had 
all those accurate nixie digits and the cylindrical ovenized oscillator 
inside.

That thrill lasted until I found a Systron Donner nixie frequency 
counter, also with an ovenized timebase. I made one measure the other 
and vice versa, taking data with pencil and paper, and noticed slow 
cycling in both sets of readings. So which counter was right and which 
had a problem? No way to tell from the data.

It made a big impression on me that when I owned one trusted hp 
instrument I was on top of the world, but when I had two such 
instruments, they disagreed, and worse yet, there was unwanted 
variation. You've all probably been through this.

Those times were pre-GPS and I hadn't jumped into Loran-C or WWV / WWVB 
yet either. I didn't think to follow schematics or monitor voltages and 
power. Instead my solution was ... to get yet another oscillator. And 
you all know how that bad habit turned out for me.

Jim, if it's the oscillator, please do a teardown of the repair. If you 
give up, I have a spare Austron 1250A oscillator here for you.

/tvb