[time-nuts] LPRO-101 BITE (~lock) Signal Always Low

Wayne Holder wayne.holder at gmail.com
Tue Mar 22 23:36:45 EDT 2016


The signal on pin 9 starts at about 7.2 volts then slowly increments up to
14.5 volts over a period of about 138 seconds.  It then seems to stay stuck
at 14.5 volts and only repeats the cycle if I power down,w wait and then
power back on.

Wayne

On Tue, Mar 22, 2016 at 3:23 PM, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
>
> I’ve always found that pin 9 (EFC monitor) gave you a pretty good idea of
> the lock status.
>
> Bob
>
> > On Mar 22, 2016, at 8:43 AM, Wayne (gmail) <wayne.holder at gmail.com>
> wrote:
> >
> > The BITE signal is the only way to to know if it has a lock...
> >
> > Wayne
> >
> >> On Mar 22, 2016, at 4:37 AM, Bob Camp <kb8tq at n1k.org> wrote:
> >>
> >> Hi
> >>
> >> There are probably a dozen or more things that contribute to the BITE
> output. It could be
> >> a regulator out of range. It also could be the VCXO nearing tune limit.
> If the unit locks up and
> >> seems to work, I’d ignore it and move on.
> >>
> >> Bob
> >>
> >>> On Mar 21, 2016, at 9:42 PM, Wayne Holder <wayne.holder at gmail.com>
> wrote:
> >>>
> >>> I have a surplus LPRO-101 that seems to power up OK.  The power draw
> starts
> >>> at 1.7 Amps and then, after a few minutes, drops down to 600 mA, or so
> and,
> >>> after this startup, the output shows a 10.000 MHz signal thats 's
> >>> accurately as I can measure it.  The lamp voltage is 6.2 volts, which
> seems
> >>> within spec.  However, the BITE signal that's supposed to indicate lock
> >>> with a LOW level is always LOW and never changes.  The docs say that
> BITE
> >>> signal should start at a HIGH level to indicate no lock and then drop
> to a
> >>> LOW when lock is obtained.  So, this behavior seems all wrong.
> >>>
> >>> I opened the case and observed the purple glow of the lamp and probed
> >>> around IC U401, which buffers the BITE signal, and saw the same signal
> LOW
> >>> level.  U401 is getting 5 volt power and the inputs to the AND gate
> used as
> >>> a buffer for the BITE signal match what I'd expect.  But, lacking a
> proper
> >>> schematic, I'm not sure how to trace this back to the problem.  Has
> anyone
> >>> ever seen a symptom like this with an LPRO101?
> >>>
> >>> Wayne
> >>> _______________________________________________
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