Richard Knoppow wrote:
Not exactly boatanchor but pretty old. I obtained a
Hickok 890A transistor tester recently. I can find nothing
whatever about it on the web. Does anyone have a handbook or
know much about them? In particular I want to know what sort
of battery was used. It has clips for five batteries, three
are obviously for C cells but the other is evidently for a
high voltage battery of some sort. Its nearly the size of a
size-D cell but its not. I can get some action from the
calibration adjustment from two 9V batteries in series. I
think the original must have been either a 12.5 or perhaps
22.5 volt cell. If anyone can help it would be greatly
appreciated. I have posted to the test equipment list but my
posts don't seem to show up there.

It's most probably a mercury battery, either the 8.4 or 12.something
variety. As such, it's probably used as a voltage reference and replacing
it with an unregulated alkaline battery will be bad.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."