[ARC5] Tuning box

[Neil]

> On it, in yellow, it says "6V AC  R-31  Tested"

> What's an R-31?

6V may be a date code, viz. June 22.
AC may be a year code, viz. 1942 as follows:
A=1st decade (1940-1949). Begins with AA=1940, so
AC=1942.
R-31 may be the Quality Control inspector's identifier code.

Letters A-Z for days 1-26 carries the advantage that only a
single wheel is necessary on the stamp. In this system, other
characters are necessary for days 27-31.
A similar advantage applies in the case of a two-character
year code such as AA-AJ. Additionally, the use of a two
character year code allows the stamp maker to sell the same
model of stamp for decades, the year being indecipherable
to all but the purchaser.

73 de Neil ZL1ANM