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

Bob Camp kb8tq at n1k.org
Tue Mar 22 18:23:31 EDT 2016


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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