This 10 MHz unit has a 5th pin that I can't find any documentation about. There have been posts in the past that have also indicated its use is unknown. Looking at the base, the four connections in the corners are known quantities. (ground, EFC, 10 MHz out and + supply) No. 5 is midway along one side. I thought it may be a reference supply for the EFC pin- with a 12.03 volt supply the unknown pin measures at 2.803 volts-which is usefully above the required EFC voltage ( ~2.4 volts) to bring it on frequency. But does anyone have some hard data on this 'unknown' pin? DaveB, NZ

Hi Pin 5 is the EFC reference pin. It may (or may not) have a voltage on it. If there is a voltage on it, it’s a voltage that the original OEM customer found useful. It may (or may not) have a series resistor to match up with an OEM specified trim pot. Bob > On Nov 27, 2016, at 2:04 AM, Dave Brown <tractorb@ihug.co.nz> wrote: > > This 10 MHz unit has a 5th pin that I can't find any documentation about. There have been posts in the past that have also indicated its use is unknown. Looking at the base, the four connections in the corners are known quantities. (ground, EFC, 10 MHz out and + supply) No. 5 is midway along one side. > I thought it may be a reference supply for the EFC pin- with a 12.03 volt supply the unknown pin measures at 2.803 volts-which is usefully above the required EFC voltage ( ~2.4 volts) to bring it on frequency. > But does anyone have some hard data on this 'unknown' pin? > DaveB, NZ > > > _______________________________________________ > 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.

Thanks for confirming my suspicions, Bob. I'm using a 10k 10 turn pot across the regulated 12v supply at present to feed the EFC but I'll change to using pin 5. DaveB, NZ ----- Original Message ----- From: "Bob Camp" <kb8tq@n1k.org> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Monday, November 28, 2016 3:17 AM Subject: Re: [time-nuts] Trimble 65256 OCXO > Hi > > Pin 5 is the EFC reference pin. It may (or may not) have a voltage on it. > If there is a > voltage on it, it’s a voltage that the original OEM customer found useful. > It may (or may not) > have a series resistor to match up with an OEM specified trim pot. > > Bob > >> On Nov 27, 2016, at 2:04 AM, Dave Brown <tractorb@ihug.co.nz> wrote: >> >> This 10 MHz unit has a 5th pin that I can't find any documentation about. >> There have been posts in the past that have also indicated its use is >> unknown. Looking at the base, the four connections in the corners are >> known quantities. (ground, EFC, 10 MHz out and + supply) No. 5 is midway >> along one side. >> I thought it may be a reference supply for the EFC pin- with a 12.03 volt >> supply the unknown pin measures at 2.803 volts-which is usefully above >> the required EFC voltage ( ~2.4 volts) to bring it on frequency. >> But does anyone have some hard data on this 'unknown' pin? >> DaveB, NZ >> >> >> _______________________________________________ >> 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. > > _______________________________________________ > 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.