In article ,
"Richard Knoppow" wrote:

Thanks for the reply. It might be but I tried it with a
single 9V battery and it did not seem to be enough. Two
batteries in series allowed the cal adjustment to work but I
don't want to just put 18V on it without knowing what the
actual required voltage is. I found a manual at a pay-for
site but its nearly as much as I payed for the tester.

Richard-

There is a 22.5 volt battery about the size of an AA cell, except it is
square instead of round. I used one to convert the flash in an old film
camera from two AA Cells to one 22.5 volt battery plus a similar-size
electrolytic capacitor, as a "BC" flash system. With AA cells, the
flash was not reliable. With the BC system, it never failed to fire.

I'll look through my collection of manual links for the 890. The first
one I checked had an 870, with about 30 pages scanned as individual GIF
images:

http://www.ko4bb.com/cgi-bin/manuals...Sorted/2_Misc_
Test_Equip/Hickok/870

Fred
K4DII