AT&T Bell System Plant Series Adjustment Procedure page 2

SECTION 024- 120-500
The ungrounded supply conductor should be
connected to terminal 20.
Caution: In making these measurements
care should be taken to avoid contact with
live terminals. Disconnect supply voltage
before changing terminal connections.
Electron Tube Tests
2.04
These tests will verify that the condition
of the electron tubes is satisfactory for
operation in the amplifier.
2.05
Apparatus:
1- KS-15560 or KS-15750 Tube Tester
2.06
Procedure:
(1) Test each tube in accordance with the in-
formation given in Section 100-635-101 or
100-636-101 as appropriate.
(2) Discard any tubes that fail to meet the
requirements.
Caution:
If
the amplifier has been operat-
ing, the tubes mag be too hot to handle
safely. Use asbestos gloves or ·tube pulling
tool for removing a tube.
Gain and Gain-Frequency Tests
2.07
Gain tests on the KS-16575-Ll amplifier
require care due to the amount of gain
which will be encountered. The use of shielded
connecting cords is specified. This should aid
materially in avoiding errors due to stray coup-
ling between input and output circuits when
measuring gain.
2.08
Gain is usually measured using 600-ohm
measuring sets and the 600-ohm input and
the output circuit of the amplifier which has a
600-ohm internal output impedance. If the low-
impedance "600-ohm" output is used the gain
will measure approximately 6 db higher; if the
16-ohm output is used the_ gain will measure
approximaiely 10 db lower . The tests of am-
plifier gain and gain-frequency characteristics
are made with the amplifier operating at an out-
put level of +20 dbm (0.1 watt).
2.09
Apparatus: The following equipment is
required for these tests:
1-21A Transmission Measuring Set
Page 2
2 - W3AE Shielded Cord or equivalent
equipped with a 241A plug
2~10
The 21A TMS contains an oscillator and
a power measuring system . Other oscil-
lators and measuring sets may be used provided
they have or can be arranged with additional
equipment so as to have the accuracy, frequency
range and power handling capability of the
21A TMS. In all such cases an attenuator such
as the 5A should be employed between the
source of testing power and the amplifier. The
oscillator and transmission measuring set should
be connected together, and the oscillator ad-
justed until a reading of O dbm is obtained on
the measuring set; this should be done at each
test frequency listed in Table 1.
If
any adjust-
ment of oscillator output is required to obtain a
reading of
O
dbm on the transmission measuring
set the same adjustment must be made when the
amplifier is tested.
AMPLIFIER
I
I
OSCILLATOR : POWER
I METER
I
_ 21A TMS
Fig. 1 - Gain and Gain-Frequency
Testing Arrangement
2.11
Procedure: Energize the amplifier and the
transmissoin measuring set and adjust
the oscillator for an output of -40 dbm at 1000
cycles. Connect the oscillator to the 600-ohm
input circuit ( terminals 3 and 4) of the am-
plifier. (See Fig .
1.)
Adjust the measuring set
power meter for an input level of +20 dbm and
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