Charles, The OCXO has always been pretty warm to the touch. Except now, it is barely warm. I tried the antenna first with a card sized Symmetricon GPSDO and it locked up OK. I have a small uBlox GPS that gives the signal levels of the satellites it sees. I need to hook that up and check. The Antenna is a Leica AT503 up 40 feet on a Rohn 25G tower. It is on top and seems to have a pretty good view of the sky. It is fed 12 volts from a wall wart power supply through a Pasternack bias Tee. I couldn't find any info on the AT503 but I took it apart and the preamp has a 7808 voltage regulator in it, so I think 12 volts should work alright. The cable is LMR400 from an actual HP cable intended to work with GPS. I have a lot of checking to do before I can narrow things down.
On Tue, Feb 2, 2016 at 1:06 PM, Charles Steinmetz <[email protected]> wrote: > John wrote: > > I am now thinking it may be an OCXO outer oven failure. It normally >> runs quite warm. But now, it seems it may be body temperature or maybe a >> little less. The 10811 is different to a stock one but, is the outer oven >> voltage the same? I would think the inner oven should keep it warm enough >> to achieve lock and hold it. The outer oven is mostly to make the inner >> oven's job easier. >> > > Typically, the outer oven of a DO 10811 is on a thermostat. It receives > power only when the OCXO is warming up from cold, and is switched off when > the inner oven gets close to its operating temperature. So, the outside of > the OCXO package is warm during warmup from cold, then less warm during > normal operation. If the outer oven does not heat, for any reason, the > inner oven will eventually (~30 min.) get the crystal to operating > temperature and it will work normally after that. > > The symptoms you have described all suggest very strongly that something > is wrong with the antenna feed to the 3801: > > -- bad antenna location (needs to be outdoors with a clear view of at > least the southern half of the sky, assuming you are in the Northern > hemisphere) > > -- bad antenna > > -- no DC power reaching antenna > > -- bad antenna cable > > -- bad antenna cable connector(s) > > It's possible something is wrong with the 3801, but if it worked properly > when it was taken out of service, it is *much* more likely that the problem > is one of the items listed above. > > Best regards, > > Charles > > > _______________________________________________ > 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.
