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Model 5065A
Circuit Diagrams, Theory, and Maintenance
i.
Remove the A11 Temperature Regulator circuit
board and replace A11R5 and A11R6 with the new R5 and
R6 calibration resistors.
j .
Install new Power Supply Regulator Assembly
supplied with replacement RVFR Assembly.
k.
Locate the twisted pair of black and red wires
from the RVFR Assembly. Solder the black wire to pin 1
of socket XA8 and the red wire to pin 1 of socket XA4.
I.
After the A12 RVFR Assembly has been replaced
the instrument should be turned on and warmed up for at
least four hours before following the LOOP ALIGNMENT
PROCEDURE in paragraphs 5-19 through 5-31.
If the A1 synthesizer thumbwheel set
ting are changed or service is performed
on A14, allow 1 minute of recovery time
before attempting to place in the con
tinuous operation mode.
BUFFER AMPLIFIER ASSEMBLY A13 THEORY
This assembly has two buffer amplifier circuits which
deliver 1 volt (into 50 ohms), 5 MHz outputs. One out
put goes to A1 Synthesizer Assembly and the other out
put to front and rear 5 MHz output jacks.
R1 provides a 50-ohm input at J1. Buffer amplifier stage
Q2 amplifies the input 5 MHz signal for a 1-volt, 5 MHz
output at J3. Buffer Amplifier stages Q1 and Q2 provide a
1-volt, 5 MHz output at J4 for the rear 5 MHz output and at
J2 for the front panel 5 MHz output. Additionally, Q3 out
put is rectified by CR2 and filtered by C11, R17, and C12
for a dc output to the 5 MHz position of the CIRCUIT
CHECK meter. Bias voltage for all three amplifying stages
is provided by Zener Diode CR1. Selected capacitances
C7 and C8 provide tuning for T1 and T2 respectively. The
+20 volt supply is decoupled by L1 and C1.
A13 MAINTENANCE
NORMAL OPERATION
b.
Output at J3 is approximately 3V peak-to-peak
into an open circuit.
c.
Output at J4 and J2 is 1V rms into a 50 ohm load.
d.
Output at C2 is approximately 90 to 120/u a for
operation of front panel meter.
No adjustments are provided.
ASSEMBLY REPLACEMENT
No adjustments are needed after repair or replacement —
of this assembly.
NOTE
a.
Input signal is 1V rms.
8-58
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