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

Tom Miller tmiller11147 at verizon.net
Tue Mar 22 02:06:09 EDT 2016


----- Original Message ----- 
From: "Wayne Holder" <wayne.holder at gmail.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Monday, March 21, 2016 9:42 PM
Subject: [time-nuts] LPRO-101 BITE (~lock) Signal Always Low


>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
> _______________________________________________

Does it need a pull up resistor?




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