[time-nuts] 5061A Problem Child

Charles P. Steinmetz charles_steinmetz at lavabit.com
Wed Jun 16 03:05:06 UTC 2010

Joe wrote:

>Short of fabricating a 'phase detector', how can I prove that the A3 unit is
>functioning in my 'problem child' unit.  If I have to fabricate a 'phase
>detector', how easy (or difficult) is that?

I have no idea how much phase modulation there is supposed to be.  If 
it is substantial, you might get a crude qualitative idea by looking 
with a stably-triggered 'scope at a scale where there are, say, 10 
cycles per cm (~100 cycles across the screen).  If the signal at the 
right of the screen is fuzzy (cycles run together) while at the left 
it is sharp (cycles clear and distinct), you have phase 
modulation.  Turning the mod off should make the signal look sharp at 
both ends.

If you are lucky enough that the modulation is sufficient to show up 
this way, you can compare the two units to see if the progression 
from sharp to fuzzy looks about the same from one to the other.

I like Didier's suggestion of the FM tuner, but the phase modulation 
will need to be substantial to detect it that way.

Best regards,


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