Operating instructions

ACCEPTANCE TESTING
5-21
(20) Check that the deviation reading on the UUT drops by approximately half, i.e. to 37.5 kHz.
(functional check).
(21) Press [Deemph] to switch the de-emphasis filter off and then [Return], [Scope/Bar],
[Bar Chart], [Return], to switch the oscilloscope off.
(22) Remove the splitter and Modulation meter and connect the RF signal generator directly to
the UUT antenna input.
(23) 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.)
(24) Note the voltage reading on the DVM connected to the DEMOD OUT socket of the UUT
(Reading 1).
(25) Switch the RF signal generator modulation off and note the reading on the DVM
(Reading 2).
(26) Calculate the residual FM as shown below and check that it indicates 35 Hz or less
(functional check only).
(Reading 2 ÷ Reading 1 )
× 5000