I don't currently have a way to accurately measure the frequency of the output, but my assumption is that oscillator is running, but not locked. I did some more poking around and found that the crystal volts monitor (pin 9) starts low (around 4 volts) and then slowly rises as the unit runs. It rises to about 14 volts and then stops. So, this may be a similar problem to what you described. However, lacking proper schematics, I'm not sure where to look next.
Wayne On Tue, Mar 22, 2016 at 8:43 AM, iovane--- via time-nuts <[email protected] > wrote: > Wayne, > > are you sure your LPRO actually locks? You say you have measured 10.000 MHz > but you don't mention the other decimals. Some years ago I characterized > some > LPROs of mine, and from my notebook I take that, on one sample for > instance, > prior to lock the frequency swept up and down between (about) 9.999860 and > 10.000230. Such a span was rather typical among units. A faulty unit of > mine > remained stuck at the upper limit without reversing the sweep. This was > due to > a faulty resistor in one of the two (upper) voltage comparator circuits. > Anyway > I don't know if this would affect the BITE, but I suggest you to check the > other decimals. > > Antonio I8IOV > > > > >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 <[email protected]> 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 <[email protected]> > 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 > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
