Teletype 28 - 3.13 Contact Timing Measurements (To Zero Test Set)

ISS 8, SECTION 573-118-700TC
3.13 Contact Timing Measurements (To Zero Test Set)
The following
tests require the use of a Teletype signal distortion test set. They should be made
after the contact assemblies have been adjusted as instructed on the preceding pages. Where re-
quirements are not met, designated adjustments must be refined, and/or related lengths may
have
to be changed to meet timing requirements.
Tests on 600 operation per minute units or lower should be made with the perforator or reper-
forator and the test set operating at 600 opm. Tests on 900 opm units used on the automatic
send-receive (ASR) set should be made with the test set operating at 600 opm and using keyboard
transmission. Tests on 1200 opm units should be made with the reperforator operating at 1200
opm and the test set equipped with a two-cycle scale and operating at 600 opm.
Observations are to be made of a neon trace on the graduated disc of a test set. Trace will
have tendency to "jump"; that is, it will not be steady enough to be accurately measured. Varia-
tion may be as high as ten divisions on scale. Minimum signal length is measured between latest
start and earliest end of all traces. Maximum signal length is measured between earliest
start and latest end of all traces.
ONE-CYCLE SCALE
To Zero Test Set
VARIATION
EARLIEST START
SCALE
ZERO MARK
NEON TRACE
Connect neon
trace to no. 1 code reading contact (rearmost). With unit receiving LETTERS
code combination, observe and note point ~t which trace ends. Traces will jump as described
above; note earliest end of traces. Repeat for remaining contacts. Of all traces observed,
choose one that starts the latest. Set "start-zero" mark of scale at latest start of chosen
trace. Record earliest end of chosen trace for future adjustment references.
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