0 These tiny collectable 1960s transistor sets seem to be available on
ebay all the time.


1 First and foremost kudus to Wumpus who has posted an online pictorial
on how to use modern zinc air hearing aid batteries in an SR-H436 ruby.

http://www.oldradioworld.de/srh436.htm

2. Based on this site, I tried using some hardware I had on hand and
found that a perfect spacer was easy to make with #6 brass hardwa a
6-32 machine screw, eight thin flat washers, one hex nut. #6 sized
brass is easy to machine: i.e. cutting down the screw length using
dikes , and a steel 6-32 hexnut can be used as a die to clean up the
threads on the brass screw after trimming it to length.

3. After a few successive trimmings of the screw, my spacer ended up
(the assembled screw, washers, nut) to an overall length of .457".

4. My spacer does have the screwtip sticking out past the nut like it
does in the Wumpus pictures. Instead the screw is recessed down inside
the hexnut, so that the nut (instead of the screwtip) contacts the
radio. Using more or fewer washers allows having the nut extend just
slightly past the tip of the screw.

5 Using 675 (i.e. blue) hearing aid batteries I do not need the paper
tubes which Wumpus shows. I just cut a strip about 5" long of gray duck
tape .200" wide and wrapped it around the stack of washers on the
spacer until that the diameter of spacer roughly equaled that of the
batteries, this leaves the screwhead and hexnut extending out of the
tape so they are not covered by the tape like the washers are.

6. I use no covering around the batteries (Wumpus used a paper tube)
because the stack of two batteries and the spacer holds tight in the
radio, and does not ever lose electrical contact as the radio is
jostled. The longest part of battery replacement is unscrewing the
radio cover with a disme, after that it takes 10 seconds to swap
batteries.

7. The discontinued Eveready 640 size alkaline cells have a mAh rating
of 325 and costed $5 each at Radio Shack.

8. #675 zinc airs are $36 including shipping for a case of sixty
Toshibas at www.microbattery.com/. And these are rated at 651 mAh !

9. A couple hours ago my tiny SR-H436 picked up 20 listenable stations
during the daytime, a dozen loud and clear, with good selectivity, very
nice performer.

oops, sorry guys. I accidently posted in the wrong group, my mistake....