ACCEPTANCE TESTING
5-27
(14) Set the RF signal generator modulation rate to 10 kHz and the UUT AF Filter to 50 kHz LP.
Check that the deviation level indicated on the UUT is within ± 7.5% ± UUT resolution of
the deviation indicated on the Modulation meter.
(15) Refer to Results table 5-32 on page 5-47. On the UUT select an AF filter of 0.3 to 3.4 kHz
and an IF filter of 3 kHz.
(16) Set the external Modulation meter bandwidth to 50 Hz to 15 kHz.
(17) Set the RF signal generator modulation rate to 1 kHz and set 250 Hz deviation.
(18) Check that the deviation level indicated on the UUT is within ±5% ± UUT resolution of the
deviation indicated on the Modulation meter..
(19) On the UUT select an IF filter of 30 kHz . Set the RF signal generator to provide a deviation
of 10 kHz and check that the deviation level indicated on the UUT is within ±5% ± UUT
resolution of the deviation indicated on the Modulation meter.
(20) On the UUT select an IF filter of 300 kHz. Set the RF signal generator to provide a
deviation of 50 kHz and check that the deviation level indicated on the UUT is within ±5% ±
UUT resolution of the deviation indicated on the Modulation meter. Repeat at 75 kHz.
(21) Refer to Results table 5-33 on page 5-48. Select the UUT demodulation oscilloscope by
pressing [Return], [Scope/Bar], [Scope]. Using the oscilloscope horizontal and vertical soft
keys select a vertical scale of 25 kHz/div and a horizontal scale of 200 µs/div.
(22) Adjust the deviation level from the RF signal generator until the 1 kHz trace on the
oscilloscope occupies the full six deviations.
(23) Check that the deviation indicated on the external Modulation meter is between 67.5 and
82.5 kHz.
(24) Adjust the deviation level from the RF signal generator until the external Modulation meter
reads 75.0 kHz deviation. Leave all settings unaltered while carrying out step 25.
(25) Refer to Results table 5-34 on page 5-48. Connect the DEMOD OUT socket on the rear of
the UUT to the DVM. Set the DVM to monitor Volts AC and check that the level indicated
is between 4.77 V and 5.83 V.
(26) Set the RF signal generator modulation rate to 2 kHz.
(27) On the UUT press [Return], [Mod Meter], [Deemph] to switch de-emphasis on.
(28) Check that the deviation reading on the UUT drops by approximately half, i.e. to 37.5 kHz.
(functional check).
(29) Press [Deemph] to switch the de-emphasis filter off and then [Return], [Scope/Bar],
[Bar Chart], [Return], to switch the oscilloscope off.
(30) Remove the splitter and Modulation meter and connect the RF signal generator directly to
the UUT antenna input.
(31) Refer to Results table 5-35 on page 5-48. Set the RF signal generator to provide a signal of
300 MHz at 6 dBm with 5 kHz deviation at 1 kHz modulation rate.
(32) On the UUT select the 0.3 to 3.4 kHz AF filter and the 30 kHz IF filter.
(33) On the UUT switch distortion measurement ON and check that the distortion reading
indicates less than 2%.
(34) Set the UUT to [Tx FREQ] 300 MHz and set the RF signal generator to provide a signal of
300 MHz with 5 kHz deviation at 1 kHz modulation rate. (The 2041 should be set to low
noise mode.)
(35) Note the voltage reading on the DVM connected to the DEMOD OUT socket of the UUT
(Reading 1).
(36) Switch the RF signal generator modulation off and note the reading on the DVM
(Reading 2).
(37) Calculate the residual FM as shown below and check that it indicates 35 Hz or less
(functional check only).
(Reading 2 ÷ Reading 1 )
× 5000
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