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Telechron Rotor Date Codes

Trying to determine Telechron rotor date codes has been pretty tricky.  I think we have it pretty much figured out.  This should allow clock owners to estimate the date of their clocks assuming they have the original Telechron rotor.

It appears that Telechron used at least 5 different date code algorithms from the 1920’s until the 1990’s.

1. From approx. late 1920’s until 1933:

Date code was simply Month (1-2 digits),Year (2 digits) (ex: 6 30 = June 1930)

The most common rotors from this era were the Brass bodied B-2’s.

2. From approx. 1933 to 1940:

Date code was Year (1 digit), Month (1-2 digits) (ex: 510 = October, 1935)

The most common rotors in the era were F’s, H-3’s with brass faces and B-2’s)

3. From 1941 to 1949:

Date code was Year (1 digits), Month (1-2 digits) (ex: 35 = May 1943)

(Note: No way to differentiate #2 from #3’s decade unless you know the style of rotor, hence the reason Telechron migrated to #4 below)

4. From 1950 to 1990:

Date code was Year (1 digit), Month (1-2 digits), Decade (1 digit) (ex: 8115 = November 1958)

5. From approx. 1990 to the end of Telechron production

Date code was 4 digits starting with 9 (ex: 9007).  My theory was that Telechron abandoned the date codes and went with production lot numbers. (ie 007 being the production lot ID within this era)

The most common rotors within this era were aluminum body S, H-3 and B-13’s

Now let’s date some sample rotors:

This one is easy.  October 1932:

This style is too late to be Feb. 1931 so it must be Feb 1941:

F rotors are pretty early so this one must be June 1936:

Transition to the 3 Digit code must make this one May 1954: (although some post 1950’s rotors can have 4 digit codes if the months are Oct, Nov, Dec)

We can’t pinpoint the date on this one with the 9XXX code but we can estimate it was one of Telechron’s last production lots sometime after 1988: