AT&T Bell System 138A Description And Use

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BELL SYSTEM PRACTICES
AT&TCo Standard
SECTION 634-200-450
Issue 1, July 1975
138A TEST SET
DESCRIPTION AND USE
1.
GENERAL
2.
PRECAUTIONS
3. DESCRIPTION
4. USE
5. MAINTENANCE
1.
GENERAL
CONTENTS
PAGE
2
3
s
1.01
This section covers the description and use
of the 138A test set.
1.02
This portable, battery-operated test set is a
precision tone generator for use in fault
locating and pair identification. This test set
generates the same 577.5 Hz signal as the KS-14t03 L6
breakdown test set and at approximately the same
output level. The 138A test set is particularly
useful in toning operations where noise or power
influence is a problem. When other tones are
difficult to detect, the 577 .5 Hz tone will be heard
if it is filtered at the pick-up point. The 1097 A
filter, provided separately, is tuned precisely to
577 .5 Hz and provides a very narrowband rejection
to all other interfering signals.
1.03
The 138A test set is designed to be used in
conjunction with the 147C amplifier, 1097 A
filter, 105D exploring coil, or 513A probe.
2. PRECAUTIONS
2.01
Caution must be exercised when making tests
so that contact is not made with any high
voltage lines.
2.02
Exercise care to protect the test set from
water damage as it is NOT waterproof.
© American Telephone and Telegraph Company, 1975
Printed in U.S.A.
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