Re: (ET) Elec-trak serial numbers

[Larry Chace <RLC1 etnainstruments com>]

At present, I have 85 ET serial and model numbers, thanks to those 
who have sent them along.  I've arranged the spreadsheet in order by 
machine type and would like to risk making a few comments and 
guestimates.

I've compared the decoded construction dates with the corresponding 
years'calendars.  The only non-weekday, non-holiday dates that appear 
are 12 October 1970 (Columbus Day, perhaps not a GE holiday?), 13 
June 1971 (a Sunday), and 4 March 1972 (a Saturday).  That makes me 
feel confident about the dates, with the proviso that there might 
have been a bit of overtime.

I've guessed that the "sequence" number is a simple running count for 
each machine type, starting at 001 and advancing, but with the 
thousands' digit being dropped (it can probably be inferred from the 
date portion).  Using that assumption, here is a breakdown of each 
machine type, showing the first and last entries from the 
spreadsheet.  I've also shown the first instance of each of the 
sub-types.  Where it is "obvious" that the sequence numbers have 
wrapped around, I've indicated what I think the actual sequence 
number would be.

08BA  DR04 799  1972 APR 04  #799
08BA  DR06 905  1972 APR 06  #905  (#905)

10CA  ER16 829  1972 MAY 16  #829
10CA  FR06 572  1972 JUN 06  #572  (#1572)

12AA  JN18 114  1970 SEP 18  #114
12BA  DP06 449  1971 APR 06  #449  (#1449)
12CA  FP22 038  1971 JUN 22  #038  (#2038)
12EA  MP13 726  1971 DEC 13  #726  (#3726)
12HA  FR02 594  1972 JUN 02  #594  (#4594)
12JD  ES23 436  1973 MAY 23  #436  (#6436)

14AA  LS12 449  1973 NOV 12  #449
14AA  CT28 797  1974 MAR 28  #797  (#797)

15AA  AN07 672  1970 JAN 07  #672
15BA  JN14 595  1970 SEP 14  #595  (#3595)
15CB  LN16 835  1970 NOV 16  #835  (#3835)  (yes, CB)
15CA  LN19 926  1970 NOV 19  #926  (#3926)  (yes, CA)
15DA  CP08 473  1971 MAR 08  #473  (#5473)
15EA  JP13 348  1971 JUN 13  #348  (#6348)
15GA  JR25 639  1972 SEP 25  #639  (#7639)
15HA  AS02 113  1973 JAN 02  #113  (#8113)

16AA  JS17 089  1973 SEP 17  #089
16RD  AT18 678  1974 JAN 18  #678  (#678)

20AA  DP20 045  1971 APR 20  #045
20BA  EP14 685  1971 MAY 14  #685
20CA  BR23 905  1972 FEB 23  #905
20DA  KR12 704  1972 OCT 12  #704  (#2704)
20FA  KS18 896  1973 OCT 18  #896  (#3896)

I5AA  FP18 025  1971 JUN 18  #025  ("25" is the I-5 in my spreadsheet)
I5BA  LR13 252  1972 NOV 13  #252  (perhaps #1252???)
I5CA  AS09 738  1973 JAN 09  #738
I5CA  BS28 987  1973 FEB 28  #987

Adding up the final sequence number for each  model, we'd have a 
total of 23,384 machines.  From 7 January 1970 until 28 March 1974 
(the first and last dates in the spreadsheet), there were about 1058 
working days, for a very rough average of 23 machines per day.

Of course, there were certainly additional machines before the 
"oldest" or after  the "youngest" in the spreadsheet, so the total 
number of machines is greater than 23,384 and the average production 
is *probably* higher then 23 per day.

Except for the 15CB and 15CA entries, all of the others show an 
"increase" in the suffix letters that advances with time.  It guess 
it is possible that GE found some "CA" parts left-over after starting 
the "CB" machines and went back for a small run of "CA".

An additional wrinkle in all of this is the possibility that some 
machines were reconditioned and, possibly, given a new serial number 
at that time.  Jim Coates mentioned to me the idea that the "Rx" 
suffices indicated reconditioned machines, and in fact there seems to 
be a consistency with the second letter of those suffices and the 
first letter of the normal model designations.  For example, E14RC, 
RD, RH, and RJ, could correspond to reconditioned E12AA, DA, HA, and 
JA machines.  The spreadsheet contains only a single "R" machine 
(16RD, and its sequence number is not "obviously" inconsistent with 
the other 2 E16 entries.

Any or all of the above may be changed based on additional serial 
numbers that might become available!

Larry Chace, Ithaca, NY  I-5 #987