DEC RK05 Emergency Retract Batteries

Robert Adamson bob at
Tue Mar 15 15:08:58 CDT 2016

Interestingly(?) both my RK05 and RK05J had an assembly of 3, not 4, 2/3rd
AA NiCd cells for retract, completely decayed of course. I replaced them
with 3 discrete tagged NiMh AA cells (plenty of headroom) soldered and
shrinkwrapped. They work fine, lots of retract force. The clip which holds
them is shaped for only 3 cells so it seems as though there were at least 2
variants. I read the circuit diagram and could see that it would make little
difference whether it was NiCd or NiMh (or for that matter 3 or 4 cells). I
think DEC were a bit overgenerous with the trickle current (though IIRC
NiCds were rather leakier back then).

> From: tony duell <ard at>
> The DEC RK07 (and I assume RK06) used 8 1/2 AA cells in a pack (like
> 2 RK05 retract batteries in series). When I replaced those, I used 2 of
> the cordless telephone batteries (that have been recommended for
> the RK05) in series.
> -tony

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