I am listening and learning. Great point on the HV supplies. When I look at the supplies I believe they are soldered cans. Is that correct?
Further had not thought about the ionizer. Skips pictures of the CBT tube clearly shows a popped ionizer. There are two oven controllers AC or the DC version. I would strongly believe the DC is quite easy to control through a FET and monostable. But this approach simply prevents multiple trips if the ION pump is re-cycling. AC maybe a bit harder. Have to actually look. On Frankenstein I built a DC controller not realizing HP used DC in later models so on that unit its very easy to do a soft start ramp. Regards Paul WB8TSL On Wed, Mar 22, 2017 at 9:33 AM, Scott McGrath <[email protected]> wrote: > 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. > _______________________________________________ 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.
