[time-nuts] Fwd: HP5061B Ion Current

John Miles john at miles.io
Tue Mar 21 20:41:29 EDT 2017

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.

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