[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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