Hi Everyone, I'm going to try to calibrate my LPRO 101 to a GPS 1pps signal. Does anyone know what "one turn clockwise" of the c field adjustment pot will do to the signal in terms of ppb ? Thanks, Alan

Hi Alan, Just did this. Less than 0.005 Hz. To really fine tune it, you need to used the C-field adjustment pin. This circuit is simple. A Linear Technology LT1236 precision 5V regulator and a 10 K linear 20+ turn pot. You can get a sample of the chip free from Linear Technology. Circuit LPRO power voltage -----LT1236---- POT---- GND | |____ >CFIELD PIN GND On the adjustment, you tweak it and wait about 10 minutes to see what it does. Then tweak again. Do this with the LPRO in its enclosure after it has run at least a day. Regards, Brian On 8/16/2013 13:41, Alan Kamrowski II wrote: > Hi Everyone, > > > > I'm going to try to calibrate my LPRO 101 to a GPS 1pps signal. > > > > Does anyone know what "one turn clockwise" of the c field adjustment pot > will do to the signal in terms of ppb ? > > > > Thanks, > > > > Alan > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.2242 / Virus Database: 3211/6082 - Release Date: 08/16/13 > > ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2242 / Virus Database: 3211/6082 - Release Date: 08/16/13

Hi Brian, >Just did this. Less than 0.005 Hz. Thank you - was clockwise 0.005 higher or lower? My Rb is about 0.000731284 fast according to my estimate. >To really fine tune it, you need to used the C-field adjustment pin. >This circuit is simple. A Linear Technology LT1236 precision 5V regulator and a >10 K linear 20+ turn pot. You can get a sample of the chip free from Linear Technology. It is connected to a RFTGm-II-Rb control board which already supplies the C-field adj pin... I may try to get a matching gps and feed it in to see if it will discipline. >Do this with the LPRO in its enclosure after it has run at least a day. I can only get to the adjustment hole outside of the enclosure, but I've tried to put it in the same thermal condition it would be normally. It is sitting on top of a heat sink with a fan on it and the temp seems about the same it as usually is so hopefully this will not affect it. Thanks, Alan