LA75693M
No.0250-8/9
V21.V22 VIF input resistance, Input capacitance [Ri, Ci]
(1) Referring to the input impedance Test Circuit, measure Ri and Ci with an impedance analyzer.
V23.V24 APC pull-in range [fpu, fpl]
(1) Internal AGC
(2) fp = 39MHz to 51MHz CW ; 10mVrms
(3) Adjust the SG signal frequency to be higher than fp = 45.75MHz to bring the PLL to unlocked state.
Note; The PLL is assumed to be in unlocked state when a beat signal appears at test point A.
(4) When the SG signal frequency is lowered, the PLL is brought to locked state again. …… f1
(5) Lower the SG signal frequency to bring the PLL to unlocked state.
(6) When the SG signal frequency is raised, the PLL is brought to locked state again. …… f2
(7) Calculate as follows:
fpu = f1 - 45.75MHz
fpl = f2 - 45.75MHz
V25. AFT tolerance frequency 1 [
Fa1]
(1) Internal AGC
(2) SG1:43.75MHz to 47.75MHz variable CW 10mVrmns
(3) Adjust the SG1 signal frequency so that the AFT output DC voltage (test point B) becomes 2.5V; that SG1 signal
frequency is f1.
(4) External AGC (Adjust the V17.)
(5) Apply 9V to the IFAGC (pin 17) and then pick up the VCO oscillation frequency from the GND, etc.; that
frequency is f2.
(6) Calculate as follows: AFT tolerance frequency
Fa1 = f2 - f1 (kHz)
V26.V27 VCO Maximum variable range (U, L) [dfu, dfl]
(1) Apply the VCC voltage to the external AGC, IF AGC (pin 17).
(2) Pick up the VCO oscillation frequency from the VIDEO output (A), GND, etc. and adjust the VCO coil so that the
frequency becomes 45.75MHz.
(3) fl is taken as the frequency when 1V is applied to the APC pin (pin 9). In the same manner, fu is taken as the
frequency when 5V is applied to the APC pin (pin 9).
dfu = fu - 45.75MHz
dfl = fl - 45.75MHz
V28. VCO control sensitivity [
β]
(1) Apply the VCC voltage to the external AGC, IF AGC (pin 17).
(2) Pick up the VCO oscillation frequency from the VIDEO output (A), GND, etc. and adjust the VCO coil so that the
frequency becomes 45.75MHz.
(3) f1 is taken as the frequency when 2.8V is applied to the APC pin (pin 9). In the same manner, f2 is taken as the
frequency when 3.0V is applied to the APC pin (pin 9).
)
mV
kHz
(
400
1
f
2
f
=
β
S1. 4.5MHz output level [Vsout]
(1) Internal AGC (V17 = VCC)
(2) fs = 4.5MHz NO MOD Vi = 10mVrms
(3) Measure the output level at test point E. ……Vsout
Note 1) Unless otherwise specified for VIF test, apply the VCC voltage to the IF AGC and adjust the VCO coil so that
oscillation occurs at 45.7MHz.
Note 2) Unless otherwise specified, leave the SW1 turned ON.