[time-nuts] HP E1938
Bruce Griffiths
bruce.griffiths at xtra.co.nz
Sun Apr 16 02:57:11 UTC 2017
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 <lmcdavid at 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 at 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 at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
More information about the Time-nuts_lists.febo.com
mailing list