Just to give back to the group, here are the connectors I chose from Digikey to make the GPS MMCX antenna included with the kit detachable for an enclosure:
1x ACX1499-ND CONN ADAPT JACK-JACK MMCX 50 OHM 1x 744-1715-ND RF CABL MMCX ML STR / ML RA 6" Cheers, Joel W0KGW On Tue, Nov 25, 2014 at 1:48 PM, S. Jackson via time-nuts < time-nuts@febo.com> wrote: > That's why I said its up to the user to decide what they want their > trade-off to be. > > For permanent installations I personally would not run the unbuffered 10MHz > output through more than about a foot of coax cable to the buffer. > > The rise/fall time of the TCXO output is slow enough (typical spec is 4ns) > to make that a lumped system rather than a reflected system. You won't see > any reflections on a foot or less of cable. > > For short-term phase noise measurements I have run that signal through 6 > feet of coax no problem, but there are quite significant reflections at > that > point so I would strongly advise against that. If I break the TCXO here on > my bench due to my own stupidity its a different situation than if the > customer has that happen in their setting.. > > bye, > Said > > > In a message dated 11/25/2014 09:34:11 Pacific Standard Time, > csteinm...@yandex.com writes: > > Said wrote: > > >The increased current for the driver will cause heating near the > >crystal in both the CMOS driver and the 3.0V LDO as the LDO has to > >convert the excess voltage into heat. This may or may not affect the > crystal. > > There would be next to no additional heating in the CMOS driver, > because there is very little voltage across it in either logic > state. And the additional power supply current is so small that the > increase in LDO dissipation will also be very low. At the extreme > worst, any such effects would be somewhere between imperceptible and > negligible. But on the other hand, if there is a possibility that a > passive filter can create a clean, 50 ohm sine wave output for free, > the potential up side is huge. > > >Adding an external buffer is so simple that I just did not think it > >would be worth it.. > > An external buffer is a fine way to go, but it would need to be very > close to the driver chip -- which is why I suggested on Sunday > building it onto a breakout card that plugs directly onto the LTE > Lite's MMCX output connector. You really don't want to run a naked > CMOS output at 10MHz much farther than that, both for the corruption > it may suffer and also for the mischief that radiation and capacitive > coupling can cause to other nearby circuitry (the LTE Lite) as the > loop gets larger than that. > > I'm not sure I see why a small additional source of heat is such a > dramatic concern with the 10MHz TCXO, but apparently not for the > 20MHz TCXO, which by accounts has an actual buffer amp that must > create comparatively massive heating. A temperature difference isn't > a problem in and of itself -- only a changing temperature creates a > problem. Whatever the dissipation situation is, it should settle > into stasis if one takes the slightest care with the thermal design. > > Best regards, > > Charles > > > > _______________________________________________ > 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.
