A friend says his Tracor 527A works fine with a 10MHz Ref input even though it doesn't have the divide by 2 circuit from the addendum to the 527E manual applied. I'm puzzled by this - I can't quite see how the reference input circuit can produce a 5MHz output when fed with 10MHz (unless his reference source has a large 5MHz sub-harmonic). Am I missing something here? On a related note, the schematic for the divide by 2 circuit in the front of the 527E manual shows a 4R7 resistor from the base of the 2N3904 to ground - this just feels all wrong!! Has anyone built this and did they change the resistor to (e.g. 47R or 4K7)? Thanks Dave

Yes, does indeed look like it should be 4K7! -----Original Message----- From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of David C. Partridge Sent: 25 June 2017 18:50 To: 'Discussion of precise time and frequency measurement' Subject: [time-nuts] Tracor 527A and 10MHz reference input A friend says his Tracor 527A works fine with a 10MHz Ref input even though it doesn't have the divide by 2 circuit from the addendum to the 527E manual applied. I'm puzzled by this - I can't quite see how the reference input circuit can produce a 5MHz output when fed with 10MHz (unless his reference source has a large 5MHz sub-harmonic). Am I missing something here? On a related note, the schematic for the divide by 2 circuit in the front of the 527E manual shows a 4R7 resistor from the base of the 2N3904 to ground - this just feels all wrong!! Has anyone built this and did they change the resistor to (e.g. 47R or 4K7)? Thanks Dave _______________________________________________ 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.

Dave will guess you are sub sampling the 10 Mhz ref. Yes it should be 4.7K. Not sure why but old military gear resistors were like that. Circa 1942 at least in schematics I have seen. Regards Paul WB8TSL On Sun, Jun 25, 2017 at 2:25 PM, David C. Partridge < david.partridge@perdrix.co.uk> wrote: > Yes, does indeed look like it should be 4K7! > > -----Original Message----- > From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of David C. > Partridge > Sent: 25 June 2017 18:50 > To: 'Discussion of precise time and frequency measurement' > Subject: [time-nuts] Tracor 527A and 10MHz reference input > > A friend says his Tracor 527A works fine with a 10MHz Ref input even > though it doesn't have the divide by 2 circuit from the addendum to the > 527E manual applied. > > I'm puzzled by this - I can't quite see how the reference input circuit > can produce a 5MHz output when fed with 10MHz (unless his reference source > has a large 5MHz sub-harmonic). > > Am I missing something here? > > On a related note, the schematic for the divide by 2 circuit in the front > of the 527E manual shows a 4R7 resistor from the base of the 2N3904 to > ground - this just feels all wrong!! Has anyone built this and did they > change the resistor to (e.g. 47R or 4K7)? > > Thanks > Dave > > > > > _______________________________________________ > 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. >

I will add the information that my 527A is totally deaf when fed with 10MHz sine wave from my t hunderbolt (no 5MHz output from input stage). D. -----Original Message----- From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of paul swed Sent: 25 June 2017 20:36 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Tracor 527A and 10MHz reference input Dave will guess you are sub sampling the 10 Mhz ref. Yes it should be 4.7K. Not sure why but old military gear resistors were like that. Circa 1942 at least in schematics I have seen. Regards Paul WB8TSL On Sun, Jun 25, 2017 at 2:25 PM, David C. Partridge < david.partridge@perdrix.co.uk> wrote: > Yes, does indeed look like it should be 4K7! > > -----Original Message----- > From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of David C. > Partridge > Sent: 25 June 2017 18:50 > To: 'Discussion of precise time and frequency measurement' > Subject: [time-nuts] Tracor 527A and 10MHz reference input > > A friend says his Tracor 527A works fine with a 10MHz Ref input even > though it doesn't have the divide by 2 circuit from the addendum to > the 527E manual applied. > > I'm puzzled by this - I can't quite see how the reference input > circuit can produce a 5MHz output when fed with 10MHz (unless his > reference source has a large 5MHz sub-harmonic). > > Am I missing something here? > > On a related note, the schematic for the divide by 2 circuit in the > front of the 527E manual shows a 4R7 resistor from the base of the > 2N3904 to ground - this just feels all wrong!! Has anyone built this > and did they change the resistor to (e.g. 47R or 4K7)? > > Thanks > Dave > > > > > _______________________________________________ > 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. > _______________________________________________ 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.