The only portion of the device with possibly significant variability is the VCO. If the design does not take care of the VCO variability, for the capture range of the PLL; things may not work.
If the device had a Phase-Frequency detector, instead of a phase detector, the capture range would not be a problem. Phase detectors are OK, when an acquisition aid is available or when the PLL closed loop BW is much larger than the max phase rate a start up. I am surprised to hear that such kind of sloppy design was allowed to be released. When I worked at Rockwell-Collins, such thing would have been a big No-No! Regards, Francesco -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on Behalf Of Javier Herrero Sent: Sunday, September 27, 2009 9:23 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 4046 variations (was EPE GPS....) Margina design? ;) Better said, very poor design. Does not sound very good that same part, same lot code, sometimes work here but not there, sometimes does not work at all... Extending it a bit... sometimes will work at a given temperature, sometimes will not at a given other. Regards, Javier Robert Atkinson escribió: > The old King Radio (then Bendix-King now part of Honeywell) Silver crown aircraft radios used 4046's in some of the synthesisers. The one in the VHF com had a different King part number to that in the ADF (MF direction finder). While trouble shooting we tried an ADF chip in a VHF (didn't have the VHF part in stock). It sort of worked but was slow to lock-up at the ends of the frequency range. Ordered some of the correct parts, both ADF and VHF. They all had the same manufacturer's part number and date code but different King numbers overstamped. Appaently the selected then at the factory for low noise (ADF) or wide pull-in (VHF). > > Robert G8RPI. > > --- On Sun, 27/9/09, Joe McElvenney <xi...@btinternet.com> wrote: > >> From: Joe McElvenney <xi...@btinternet.com> >> Subject: [time-nuts] Egg on Face (was EPE - GPS Frequency Reference Project) >> To: "Time Nuts Digest" <time-nuts@febo.com> >> Date: Sunday, 27 September, 2009, 11:00 AM >> Hi, >> >>> There's a subtle difference between 3rd phase detectors >> in the 74HC4046A >>> (Philips/NXP, ON, TI) and the 74HC4046 (Fairchild, NS) >>> The 3rd Phase detector in the 74HC4046A works as the >> designer intended >>> in the GPSDO circuit, the 3rd phase detector in the >> 74HC4046 does not. >> >>> The 74HC4046 uses an RS flipflop for the 3rd phase >> detector and requires >>> narrow pulses on the R and S inputs. >>> The 74HC4046A uses extra internal gates to ensure that >> only narrow >>> pulses are seen by the RS flipflop in the 3rd phase >> detector. >> >>> Bruce >> You are perfectly correct. I hadn't noticed that there was >> a 74HC4046A >> fitted to the board in the article but just a plain >> 74HC4046 shown in >> the parts list. However, it is something to watch out for >> as this will >> be a popular project among those, like myself, who do not >> need to slice >> time quite so finely. >> >> >> Cheers - Joe G3LLV >> >> _______________________________________________ >> 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. > > -- ------------------------------------------------------------------------ Javier Herrero EMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17A FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com _______________________________________________ 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. E-mail message checked by Spyware Doctor (6.1.0.447) Database version: 6.13350 http://www.pctools.com/en/spyware-doctor-antivirus/ E-mail message checked by Spyware Doctor (6.1.0.447) Database version: 6.13350 http://www.pctools.com/en/spyware-doctor-antivirus/ _______________________________________________ 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.