User's Manual

43
RF Section
 Check the lock of the oscillator on the whole operating range (87 - 108MHz).
 If the synthesised frequency is not correct, try to correct it by means of the capacitive trimmer of the
OSC1 reference.
 Verify the signal-to-noise ration (CCIR) of the oscillator, which should be >73dB on the whole band.
 Verify the output level by the J9 (RF OUT) connector, higher than 24.5dBm on the whole band.
 Verify that the final stage is switched off when the PLL of the oscillator unlocks.
Modulation Section
 Disable the emphasis (from the display).
 Insert the JP1 jumper (so to have an input impedance of 600Ω).
 Insert the JP2 jumper to enable the limitation circuit.
 Provide a 400Hz, 2.2Vpp banalced signal to the MONO input.
 Adjust R1 in order to have an amplitude of 3.2Vpp on TP1 (on which the oscilloscope is connected).
 Adjust R21 to obtain a deviation of ±75kHz.
 Adjust R81 to obtain the indication of the nominal deviation on the display.
 Double the level of the input signal (4.4Vpp) and check that the modulation increase is no more than 1dB.
Audio Section
 With modulation analyser and audio signal on the MONO input at 2.2Vpp, verify the frequency response
from 30 to 15kHz without emphasis. Correct any deviation from the nominal range by acting on LP1 and
LP2.
 Insert the JP4 jumper (50µs) and enable the emphasis from the display. Check the frequency response.
 Insert the JP3 jumper (25+50µs) as well and check again the frequency response.
 Verify the frequency response of the MPX input from 30 to 100kHz, calibrating R2 for the nominal
deviation with 2.2Vpp signal amplitude.
 Verify the frequency response of the SCA1 and SCA2 inputs from 50k to 100kHz, calibrating R3 and
R4 for the nominal deviation (±7.5kHz) with 2.2Vpp signal amplitude.
General
 Verify the remote switch-off function by short-circuiting pin 5 of J5 to ground.