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

Bob Camp kb8tq at n1k.org
Wed Mar 23 07:01:03 EDT 2016


Hi

Which strongly suggests that the BITE line is telling the truth. The unit is not in lock
and it’s broke. If you have the gear, you can verify this by running the tune input up and
down and seeing if the output varies by about 0.02 Hz or not. 

Bob

> On Mar 22, 2016, at 11:36 PM, Wayne Holder <wayne.holder at gmail.com> wrote:
> 
> 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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