[R-390] OA2 replacement

[Tim Shoppa]

>> I've had several OA2's (not the militarized/ruggedized, just the
>> plain jane ones) go bad in rigs over the years.  Generally they
>> intermittently fail to strike a glow and soon after outright fail to
>> glow/regulate.

> I guess the radioactive source that gets them started just goes dead
> after too many years.

Maybe.  Do all OA2's have Krypton-85 in them?  The ones that did
go bad were generally the ones that came with the Heathkits
(mostly from the late 60's/early 70's), and
they did have some warning about Krypton-85 on the side of the tube.

Looking it up, Krypton-85 has a half-life of 11 years... which
is about how old these OA2's were when they died.

Maybe the early/mid-70's OA2's have marginal quantities of
Krypton-85 in them to begin with and go bad after a decade
or two?

I have a sizable stock of OA2WA's and none of them say
anything about Krypton-85 on them.  Does this mean they
predate labeling requirements, or maybe they have some
other means of ensuring they strike?

Tim.