Acoustical Manufacturing Co. QUAD MULTIPLEX DECODER Instruction Book - Page 9

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Notes:
Each unit is fully aligned at the factory before despatch and alignment should not be required on
installation. Should subsequent re-alignment become necessary the following procedure should be
followed.
The decoder must be aligned with the printed board securely in position inside its cover. Access
to the unit is through the cover holes.
The 67 Kc/s adjustment given in paragraph (2) must be correct even if no 67 Kc/s sub-carrier is
present in local transmissions. The meter used must respond to 67 Kc/s.
The 19 Kc/s pilot tone must be accurate in frequency (± 2 c/s) and modulation level (8-10%)
from the signal generator. The modulation level of the left or right tones (400-1000 c/s) should be
20-30% .
The FM tuner should be exactly in tune during alignment.
(1)
Connect the decoder to a Quad 22 and two
power amplifiers in the normal way but
leave the FM tuner signal and HT/LT
leads disconnected. Switch the Quad 22
to STEREO-RADIO and run for 30
minutes to allow the decoder to reach
operating temperature.
(2)
Switch
Quad
22
Apply an accurate 67 Kc/s signal of
between 1 and 3 volts to the decoder input.
Page 8

ALIGNMENT PROCEDURE

to
2-MON-RADIO.
Short-circuit L2 pin 1 to chassis. Connect
AC meter (lOmV full-scale) to either
decoder output. Adjust L3 for minimum
output. Remove L2 short-circuit.
(3)
Switch Quad 22 off. Connect Quad FM
tuner to decoder.
STEREO-RADIO. Tune carefully to sig­
nal generator modulated by 19 Kc/s pilot.
Detune
L4,
adjust
maximum DC (1O-15V) across R9.
Switch Quad 22 to
L 1
then L4 for