Hi If the coil form really is plain old cardboard. I wonder what the impact of humidity is? With the heat rise and all the packing, it’s going to be a pretty indirect effect. It might be an issue on a unit that had been stored powered off for a number of years. Straight cardboard *is* an issue on RF coils in humidity.
Bob > On Nov 27, 2017, at 12:34 PM, [email protected] wrote: > > Made some measurements on a 5065A optical unit. > > -There are 3 layers in the magnetic shield. > -There is about 1/8" of insulation between the > outer and middle, and between the middle and inner shields. > -The C-field winding is wound on a cardboard form that > fits tightly into the inner shield. > -There is almost 1/2" of foamed insulation between the C-field > winding and the cell and oven forms and windings. > > Per Poul-Hennings data a 3.25 deg C change of the outer shield > will result in a 1 deg C change in the C-field coil. > > This equates to a 3.4X10-14 frequency shift when not using > active current drive. > > If the outer shield is actively held to plus/minus 1 deg C then > the shift will be held within plus/minus 1.05X10-14 as long as > the ambient temperature stays within the regulating range of the > PC liquid cooler. > > Cheers, > > Corby > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
