[ARC5] SCR-274-N Transmitter Dial Accuracy

[Michael Tauson]

The military version Type K transmitter was specified as having a
frequency precision of .03% of the dial reading.  The ATA and
A.R.C.-built SCR-274-N transmitters met this specification.  Then came
contract 1470-NY-41 and Western Electric.  The first 350 transmitters
sent to the Army's Aircraft Radio Labs at Wright Field fell into three
groups, those that met the .03% spec, those that fell outside that
spec but were within .04%, and those that failed even that.  The
latter two groups formed the majority of the equipment.  Western
Electric apparently was unable to make tuning components consistant
with the design requirements.  As a result, A.R.C. requested and got a
variance for WE that allowed the .04% radios so long as they were
tagged as such.

Apparently, WE continued to have problems since I have a BC-696-A,
serial number 29387, originally purchased for parts but with the
following legend on the dial: "Caution.  Do not rely on dial
calibration for a frequency setting closer than four hundredths per
cent."  I might well get another somewhere and restore this one simply
due to that marking.

Note that the ARC-5 transmitters were able to hold the .03% dial
reading specification.

This wasn't the only time "the big company that had to help poor
little A.R.C. out" messed up but rather serves as an example of a
company that believed its own PR too much.  I wonder how the
audiophools would react to knowing their god, Western Electric, wasn't
so perfect after all.

BEst regards,

Michael, WH7HG