Hi So, when do they go up for sale? :)
( = If and when they do, I’m still shopping for one) Bob > On Nov 16, 2017, at 3:58 PM, <cdel...@juno.com> <cdel...@juno.com> wrote: > > HP5065A C-field mods and optical unit mods > > In addition to the power supply mods: > -removed AC components > -power now supplied with an external DC lab grade low noise > highly regulated supply. > -temperature coefficient of +20 Volt supply adjusted to be > below 1PPM/deg C > See: https://www.febo.com/pipermail/time-nuts/2017-August/106634.html > > > I've now installed the improved C-field circuit that has > less than +- 1PPM variation per degree C. > > The optical unit has been installed into a sealed enclosure > that has been purged with dry Nitrogen. This eliminates > any Barometric pressure effects and also eliminates > drift caused by Helium permeation. > > Tests at this point show a very nice long term stability. > > Last mod will use a small PC closed loop liquid cooler to > keep the outside of the sealed enclosure at a constant temperature > essentially making it a double oven. > > > I'm also working on: > > An active temp compensation scheme to add to the > active barometric compensation I outlined earlier. > See: https://www.febo.com/pipermail/time-nuts/2016-May/097829.html > > And a passive optical unit temperature compensation using a > thermistor/resistor > arrangement. > > PIX shows the sealed optical unit installed into a slightly taller > chassis. (The 5065C ?) > > Cheers! > > Corby<5065crs.jpg>_______________________________________________ > 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.