[time-nuts] LPRO testing

iovane at inwind.it iovane at inwind.it
Sun Jan 20 17:50:40 EST 2013


Further, the strangest case I had to deal with was a correct voltage sweep at 
the monitor output but wrong voltage at the varactor: the issue was a leaking 
capacitor between the above voltage rail and ground, namely C406.

Antonio I8IOV

>
>lists at rtty.us wrote:
>
>>The main questions on the lockup sweep is going to be:
>>
>>1) does it make it to / past the right frequency? 
>>2) how soon after it does get there, does it lock up?
>
>It crosses the right frequency a few times until lockup, in both directions.
>According to my experience, typical lockup time for a healthy unit is 3.5min.
>
>>3) if it doesn't lock up, does it do something odd as it sweeps past the 
>right frequency?
>
>It may get stuck at either end of the sweep span. Normally the sweept 
voltage 
>(as available at the voltage monitor output) should vary between about 0.5V 
and 
>12.5V and vice-versa. If it reaches 0V or about 14V then one of the voltage 
>comparator circuits failed, and the unit gets stuck. 0.5V and 12.5V are 
preset 
>thresholds for the voltage comparators. I happened to come across both 
cases, 
>and the failing components were 100K resistors.
>
>Antonio I8IOV



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