John makes a good point about the ionizer filament has anyone done a 'slow start' system for the Ionizer filament?
I.e. Limit the inrush current as is done for expensive high power transmitting tubes? > On Mar 21, 2017, at 9:44 PM, Donald E. Pauly <[email protected]> wrote: > > It looks like that there is about 10% hysteresis on the cesium trip > off/on. That may not be enough to prevent cycling on and off. I may > not have made it clear but instability in the +3,500 voltage makes a > big difference in the threshold ion current required for activation. > If it fades it can require a 10 uA smaller ion current to activate > cesium. > > ---------- Forwarded message ---------- > From: John Miles <[email protected]> > Date: Tue, Mar 21, 2017 at 5:41 PM > Subject: Re: [time-nuts] Fwd: HP5061B Ion Current > To: Discussion of precise time and frequency measurement > <[email protected]>, [email protected] > > > That's some very nice work, Donald. Looking back, I have junked one > or two Cs tubes that might have been usable if I'd thought through the > problem of high ion pump current as you and KB7APQ seem to have done. > > Another good reason to raise the lockout threshold would be to cut > down on the repetitive ionizer filament cycling that the tube will > otherwise undergo when you first fire up the oven. That phenomenon > always makes me reeeeally nervous. > > -- john, KE5FX > Miles Design LLC > >> -snip- >> When we overrode the cesium lockout at 29 μA or so of ion current, we >> needed only minor front panel adjustments for beam current of 20 μA. >> (We shorted across A15 R-4.) Our last ion current before power supply >> modifications at risen to 39 uA. Beam current has been stable. >> > _______________________________________________ > 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.
