Instruction manual

TM 11-6625-3017-14
(2) Connect the voltmeter to the OUTPUT terminals.
(3) Turn the DE-EMPHASIS switch to 75
µ
sec, the
Function switch to DEV+ and the MAX MOD FREQ
to 200 kHz.
(4) Set the signal source frequency to 100 Hz and
adjust its output level to give a suitable reference
deflection on the output voltmeter.
(5) Vary the signal source frequency, keeping the
output level constant, and check that the response
relative to the 100 Hz reference is within
±
1 dB of:
-3 dB at 2. 1 kHz.
-16.9 dB at 15 kHz.
(6) Repeat step (5) with the DE-EMPHASIS switch set
to 50
µ
sec and check that the response is within L.
dB of:
-3 dB at 3. 15 kHz.
-16.9 dB at 22.5 kHz.
5.4.7 Range attenuator
Test equipment: j and k
(1) Connect the signal source as in step (1) of
Sect. 5.4.6.
(2) Connect the voltmeter to monitor the signal source
output.
(3) Turn the DEV RANGE switch to 5 kHz and the DE-
EMPHASIS switch to OFF.
(4) Set the signal source frequency to 1 kHz and adjust
its output to give full-scale deflection on the TF
2300A meter.
(5) Turn the DEV RANGE switch to 15 kHz. Increase
the signal source output by 10 dB and note that the
meter reads within 1l% of full-scale.
(6) Repeat step (5) for the 50, 150 and 500 kHz
deviation ranges.
(7) Switch off the TF 2300A, remove the test
equipment and reconnect the yellow lead to the
discriminator output.
5.4.8 A.M. and l.f. response
Test equipment: j and k
(1) On the a. m. detector unit (All) disconnect the links
from pins 17 and 18. Then connect the signal
source between pins 18 and 10 (earth).
(2) Turn the % A. M. RANGE switch to 100% and the
Function switch to A. M. PEAK.
(3) Connect one voltmeter across the OUTPUT
terminals and another to monitor the signal source
output.
(4) Set the signal source frequency to 10 kHz and its
output to give a reading of 100% on the TF 2300A
meter. Note the reference level on the output
voltmeter.
(5) Vary the signal source frequency, keeping the level
constant, between 30 Hz and 50 kHz and note that
the reading on the output voltmeter is flat to within
±
0. 25 dB of the reference level.
(6) Switch off the TF 2300A, remove the test
equipment and replace the link between A11 pins
17 and 18.
5.4.9 Discriminator trigger
Test equipment: a
(1) With the modulation meter switched off disconnect
the lead from pin 2 on the discriminator unit (A5)
and connect the multimeter to the collector of A5Q2
(or Q3).
(2) Switch on and adjust A5RVl to a point where the
circuit is at change of state, i.e. multimeter either
reads 0 V or 15 V. When the potentiometer is
adjusted the voltage will jump either to 15 V or 0 V
from the original reading. Set to a position just
before it jumps.
(3) Transfer the meter to pin 7 (i. e. test point adjacent
to RV1). Note the voltage and decrease it by 0.5 V
by rotating RV1 counter-clockwise. Check that the
output waveform at the output terminals of the
instrument is free from spurious pulses. Switch off
the TF 2300A and reconnect pin 2.
5-7