Frequency Adjustment; S-Meter Adjustment - Icom IC-720A Instruction Manual

9-2-2 P.B.T. FREQUENCY ADJUSTMENT
Connect the input terminals of the frequency counter across
the check point at R24 and ground of the IF Unit, and per-
form the following adjustments.
(a) Turn R19 fully counterclockwise.
(b) Place the set in receive in the USB or LSB, and turn the
P.B.TUNE Control fully clockwise. Adjust coil L7 for
a frequency of 19.7633MHz.
before click OFF), and set the mode to AM. Adjust
R115 for 19.7567MHz, then set the mode to USB or
LSB, and adjust R114 for 19.7597MHz.
Р.В.Т. Frequency and IF Gain Adjustment
R167 AM IF GAIN Adj.
PESE
R76 IF GAIN ШИНА
с ШЕ"
L7 (b)
R14 (f)
R13 (e)
R24 =
Connect frequency counter...
ұс
А
+
9-2-3 RECEIVER IF GAIN ADJUSTMENT
With the receive frequency set to 14MHz, mode to USB,
AGC fast, RF GAIN fully clockwise, P.B.T. in the center
Position, connect the signal generator to the antenna con-
пестог. MAKE SURE THAT THE SET IS IN THE RECEI-
VE MODE! IF NOT, THE GENERATOR WILL ВЕ
DAMAGED!
(a) Adjust the signal generator frequency to the receive
frequency (so that a beat note is heard) and set the
signal generator output to 20dBuy, and adjust the AF
GAIN control to obtain about 2 volts for ОдВ reference
on the AC millivoltmeter connected across the speaker.
(b) Turn off the signal generator output and the AC milli-
voltmeter reading should drop 30dB. If not 30dB,
adjust R76 in the IF unit to reach that.
(c) When the optional AM Filter is installed adjust R167
receiver (or S-meter reading) with the P.B.T. OFF and
with it ON and centered.
9-2-4 S-METER ADJUSTMENT
Set controls and connect the signal generator the same as
9-2-3.
йүз Е
ракот У
—32—
19.7600MHz.
R115 (c)
Бл. 2-2. сй (с)
(а) Тит off the signal generator output, and adjust R83
on the MAIN unit to indicate the "0" point on the
scale.
(b) Adjust the signal generator frequency to the receive
frequency and set the output to 629Ви, and adjust
R79 for full scale.
(с) Decrease the signal generator output to 224Ви, and
adjust R81 for S-9.
S-Meter Adjustment
R83
Adjust for 0 point
R79
Adjust for Full Scale
R81
Adjust for S-9