Fluke 6080A - Page 170

TROUBLESHOOTING AND REPAIR
FREQUENCY SYNTHESIS
Table 6C-10. A12 Sum Loop PCA RF Section DC Bias Voltages
Table 6C-11. A12 Sum Loop PCA Test Points
6C-40
LOCATION
Q1 collector
Q2 collector
U7 output
U8 output
Q5 collector
Q6 collector
Q8 collector
Q9 collector
Q10 collector
Q11 collector
CIRCUIT
U1 LO amplifier
U1 LO amplifier
U1 RF amplifier
U1 RF amplifier
IF1 amplifier
IF1 amplifier
FM amplifier
IF2 amplifier
IF2 amplifier
ECL/TTL buffer
VOLTS DC
+9.8
+4.9
+4.7
+4.7
+9.5
+3.5
+9.8
+6.4
+8.5
+1.0
TEST
POINT
TP1
TP2
TP3
TP4
TP5
TP6
TP7
TP8
TP9
TP10
TP11
TP12
TP13
TP14
TP15
SIGNAL
TYPE
DC+audio
audio
DC+audio
DC+audio
DC+audio
N/A
TTL
TTL
DC+audio
N/A
N/A
RF*
RF*
RF*
Ground
RANGE
± 4V
0 to 3.0V RMS
0 to 26.0V
± .8V
± 150 mV
TYPICAL
0V
0V
15V
0V
0V
SIGNAL DESCRIPTION
Loop amp low frequency output
SUMAUDIO buffer amplifier output
Sum Loop VCO steering voltage
Sum Loop VCO phase lock voltage
Phase detector voltage
This test point is an input for sum loop test and alignment.
TTL high, low
TTL high, low
± 4V
TTL high
TTL high
0V
Loop disabling one-shot output signal
Acquisition oscillator switching signal
Filtered loop amp LF output
This test point is shorted to ground for sum loop test and alignment.
This test point is shorted to ground for sum loop test and alignment.
-20 to -28 dBm
480-1056 MHz
2 to -4 dBm
576-968 MHz
-13 dBm
80 MHz
-24 dBm
600 MHz
+2 dBm
696 MHz
-13 dBm
80 MHz
Buffered Sum Loop VCO signal
Amplified Coarse Loop VCO signal
Buffered FM oscillator signal
* RF Levels are approximate and are measured using a 500-ohm probe with a spectrum analyzer.