More precisely the active EFC range is +1.25 to +3.75V with an absolute minimum of 0V and an absolute max of +5V.
At least this is the range that the pseudo differential AD7714 ADC inputs monitoring the EFC are configured for. Bruce > On 16 April 2017 at 14:57 Bruce Griffiths <bruce.griffi...@xtra.co.nz> wrote: > > > 0 to +5V dc max, however only the 0 to 2.5V range appears measurable by > the AD7714 ADC on the PCB. > > Increasing the EFC voltage decreases the capacitance in series with the > crystal requiring an increase in the inductance exhibited by the crystal > hence requiring a lower oscillator frequency. > > Bruce > > > > > > On 16 April 2017 at 13:01 Larry McDavid <lmcda...@lmceng.com> wrote: > > > > The units now available on eBay have various types of D-Subminiature > > connectors and can be on either side of the board. I will have to > > wait > > until my unit arrives to see what I get. It should be possible, if > > necessary, to remove the connector and replace it with a more > > convenient > > D-Submin connector on the desired side of the board. > > > > I did not originally note the additional zip'd info available from > > that > > eBay website but now have those files. Thanks for that link. > > > > So far, I have not seen any spec for the EFC voltage and polarities > > used > > in the "Integrated PWB." Anyone know that? > > > > The "full instrument" version also available now on eBay is a > > complete > > GPSDO but at $130 plus $80 shipping. I really don't need yet another > > GPSDO but would use the integrated PWB assembly for a low ADEV > > free-running 10 MHz source. I have a HP 10811D for that now but will > > evaluate this new unit for performance. > > > > Anyone have experience doing this and know the EFC requirements? > > > > Larry > > > > On 4/15/2017 4:01 PM, Richard (Rick) Karlquist wrote: > > > > > > > > > > It's been 20 years, but I will try to recap what I remember > > > about this connector. I believe there were 3 customers, > > > and one of them required the DB connector with coax inserts > > > for reasons of backward compatibility. I think this > > > vendor was Motorola. We did not actually use the coax > > > inserts, but left them blank and ran the RF, etc on > > > ordinary pins. I believe you can make an ordinary male > > > DB-25 mate with these insert versions by clipping off some > > > of the pins that would be blocked by the female insert > > > version. I vaguely remember that the other 2 vendors > > > used gender changers or something. There might have > > > an issue with the mating plane location being different > > > for different customers. > > > > > > I am sure that time-nuts, being talented at repurposing, > > > will be able to think about this problem and come up with > > > a simple solution to interfacing with these boards. > > > No need to buy insert type connectors. I never had > > > any trouble making cables that connected to these units > > > using plain vanilla DB25's. > > > > > > Rick N6RK > > > > > > On 4/15/2017 10:42 AM, Larry McDavid wrote: > > > > > > > > > > > > > > Ok, so a standard DB 25-pin socket-contact connector > > > > will mate with the > > > > on-board connector with the center hole and missing > > > > pins. That's good! > > > > > > > > I now notice a comment on your webpages about this > > > > device in which you > > > > mention a schematic. Do you have a schematic of this > > > > board? If so, can > > > > you point to it or send me a copy. > > > > > > > > I was unaware of the complete packaged unit on eBay; > > > > thanks for that. > > > > > > > > Another poster mentioned the wiring of the connector on > > > > the full > > > > instrument version power connector; is that pin-out and > > > > spec available? > > > > > > > > Larry > > > > > > > > On 4/15/2017 5:05 AM, Tom Van Baak wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I purchased one of these HP E1938 OCXO > > > > > > recently on eBay but have not > > > > > > yet > > > > > > received it. > > > > > > > > > > > > Is that special D-Submin connector a > > > > > > receptacle-shell, pin contact > > > > > > version? Will a standard plug-shell, socket > > > > > > contact 25-pin D-Submin > > > > > > fit it? > > > > > > > > > > > > > > > > > > > > > > Hi, > > > > > > > > > > I'll cc the group here since we may get some > > > > > useful comments. > > > > > > > > > > I'm not exactly sure what you mean. The E1938A > > > > > oscillators that I've > > > > > seen and tested look like this: > > > > > > > > > > http://www.leapsecond.com/museum/e1938a/ > > > > > > > > > > And those can be interfaced with a simple D-sub > > > > > DB25 connector on the > > > > > PCB. For connections, see that page, or any > > > > > number of postings about > > > > > the E1938 in the time-nuts archives. > > > > > > > > > > Note that on eBay there are at least three > > > > > variations of E1938A > > > > > oscillator. The item#'s below are just random > > > > > search picks (I have no > > > > > affiliation with any buyers or sellers) and I > > > > > also know not all > > > > > surplus refurbished surplus recycled surplus > > > > > stuff works. But we do > > > > > this because when they did work, they are > > > > > sometimes totally amazing. > > > > > > > > > > 1) There's the bare "puck" alone, as in > > > > > http://www.ebay.com/itm/290829077542 -- and I > > > > > have no idea where one > > > > > would start with that item since all the support > > > > > circuitry on the PCB > > > > > would have to be re-created by hand. > > > > > > > > > > 2) There's the integrated PCB assembly, as in > > > > > http://www.ebay.com/itm/181043193416 -- which is > > > > > more like what I > > > > > tested. > > > > > > > > > > 3) There's the full instrument version, as in > > > > > http://www.ebay.com/itm/171293069062 -- which is > > > > > most likely to work, > > > > > or be less hacked up, or dented, or salvaged, or > > > > > rusted. It even has > > > > > all the connectors and power supplies, and GPS, > > > > > etc. > > > > > > > > > > If any other time nuts have experience with each > > > > > of these methods to > > > > > obtain a E1938 oscillator, please let us know. > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > 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. > > > > > > > > > > > > > > > > > > -- > > Best wishes, > > > > Larry McDavid W6FUB > > Anaheim, California (SE of Los Angeles, near Disneyland) > > > > _______________________________________________ > > 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.