TROUBLESHOOTING AND REPAIR
RF LEVEL/AM
RF LEVEL ADJUSTMENTS 6D-10.
The Output Section adjustments listed below are covered in the following paragraphs:
• Modulation Control PCA, A11
R23, Level DAC Offset Adjustment
R8, AM DAC Offset Adjustment
R28, Detector Offset/Linearity Adjustment
R10, AM Depth Adjustment
R20, RF Level Adjustment
R71, External Modulation Level Indicator Adjustment
R99, Sum Loop Steer Gain Adjustment
• Premodulator PCA, A10
R51, C7, AM Bandwidth Adjustment
• Output PCA, A8
R96, Q16 Bias Adjustment
R1, Q9 Bias Adjustment
R72, Het Mixer Level Adjustment
R10, Het Gain Adjustment
C201, Gain Flatness Adjustment
R82, R101, and R102 are related to FM performance and are discussed under the
heading "Alignment of FM PCA (A14)" in Section 6E.
Any adjustment can be made independently unless it is noted that it interacts with
another adjustment. Interdependent adjustments must be done in the sequence
presented. If more than one adjustment is necessary, do them in the sequence
presented.
Mod Control PCA Level DAC Offset Adjustment, R23 6D-11.
TEST EQUIPMENT:
•
DVM
REMARKS:
The level DAC offset adjustment is normally required only when U4 or any associated
components are replaced.
CAUTION
This adjustment directly affects the output level and should not be made
indiscriminately.
PROCEDURE:
The level DAC offset, R23, is adjusted for 0 ±0.5 mV at TP7 with the RF OUTPUT
off.
6D-10
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