AT&T Bell System Plant Series Description And Application Manual

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BELL SYSTEM PRACTICES
Plant Series
SECTION 100-629- 101
Issue 1, April, 1958
AT&TCo Standard
KS-15840, LIST 1 MICROMHOS METER CALIBRATOR
DESCRIPTION AND APPLICATION
1. GENERAL
1.01
This section describes the KS-15840,
List 1 micromhos meter calibrator. It is a
small portable unit for checking the accuracy
of the micromhos meter of any KS-type tube
tester of Hickok Electrical Instrument Company
origin.
1.02
The calibrator has been designed to re-
place Western Electric Company opera-
tional standard electron tubes which were used
to check the micromhos meter indications of the
KS tube testers:
1.03
The calibrator does not provide a check
of the accuracy of the micromhos meter
by itself. It does check that the various meter
shunt arrangements provide consistent indica-
tions on the meter and that the tester is func-
tioning properly to indicate the test results on
the meter. It also provides a check of some of
the principal overlapping scale points on the vari-
ous scales. The check of functional operation is
essentially what was accomplished by the op-
erational standard tubes. It will not eliminate
other maintenance tests specified for KS testers
in their respective Bell System Practices.
2.
DESCRIPTION
General
2.01
The KS-15840, List 1 m.icromhos meter
calibrator is self-contained in a small
case for portable use. It is equipped with
a rubber-covered cord and a 5-pin male plug
for connecting to the set to be tested. The over_,
all dimensions of the calibrator are 6¼ inches
long by 3¾ inches wide by 2½ inches high. The
weight is 1 pound 10 ounces.
2.02 The front panel (Fig. 1) contains a
calibrated ac iron-vane voltmeter with
controls consisting of a 2-position slide-switch
designated RANGE and a potentiometer marked
METER ADJUST. Brief operating instructions
also appear on the front p~nel.
Hi 3000
Lo6000
METER
0
ADJUST
R
0
:i
EQ
Lo60Q
SET SELECTORS JR 0300-0
FOR 3000-6000 POSITION
SET FIL. SW ON 35 V
@
@
FOR 600 POSITION SET FILSW ON 20V
@KS-15840,LI SER.NO
@)
Fig. 1 - Micromhos Meter Calibrator,
Panel Layout
2.03
The rear of the case has a label which
contains more detailed operating instruc-
tions and a table of requirements.
2.04 It is important that the calibrator be used
in a horizontal position on a firm and level
surface because the voltmeter is calibrated for
an accuracy of +0.25 per cent, and because the
meter is somewhat sensitive to position.
Circuit Description
2.05
The circuit used in the KS-15840, List 1
calibrator is designed to simulate a tube
being tested in a KS tube tester. This is accom-
plished through an ac voltage and appropriate
values of resistance which simulate plate im-
pedance. The micromhos meter readings thus
obtained can be compared with ideal require-
ments. This circuit is essentially the same as
that used by the supplier to check the KS tube
testers.
2.06
Fig. 2 is a schematic circuit of the cali-
brator. Two of the leads from the plug
are bridged across the 1000-ohm potentiometer
©
American Telephone and TeleKraph Company, 1958
Printed in U.S.A.
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