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Model 5065A
Circuit Diagrams, Theory, and Maintenance
6)
Adjust Oscilloscope for a pattern similar to
Figure 5-2.
If waveform looks like Fig
ure 5-1, phase and/or amplitude are mis-
adjusted.
Perform Loop Alignment, Para
graphs 5-19 through 5-31.
If waveforms
look like Figure 5-2 in shape and
not
necessarily in amplitude, continue to next
step.
7) Adjust A3R3 and A3R11 fully ccw, then ad
just cw Vi turn until the oscilloscope pattern
just splits.
Readjust A3R3 and A3R11 cw
slightly to where the pattern is similar to
Figure 5-2. Splitting is observed at the lower
right and left ends of the waveform.
8)
Remove oscilloscope connections and replace
top cover.
Set OSC. FREQ. ADJ. FINE to
250 and set FUNCTION switch to OPERate.
9)
Press LOGIC RESET pushbutton.
CONTIN
UOUS OPERATION light will come on and
stay on.
Figure 5-1. A8TP3 Waveform at 200 x 10-'° and
Phase Misadjusted
Figure 5-2. A8TP3 Waveform at 200 x 10'° and
Phase Correct
Table 5-2. In-Cabinet Performance Check
1. CIRCUIT CHECK METER CHECK
The circuit checks below involve setting the front
panel CIRCUIT CHECK switch to all its positions
and observing the corresponding indication on
CIRCUIT CHECK meter. Switch positions and nor
mal indications are listed in Table 5-3. Perform the
circuit checks as follows: Set CIRCUIT CHECK
switch to all its positions. CIRCUIT CHECK meter
indications should be as in Table 5-3.
2. OUTPUT FREQUENCIES
Place instrument in operation (CONTINUOUS
OPERATION light on, ALARM light off).
Connect 5 MHz from a Primary Frequency Standard
as an external time base to an Electronic Counter.
Connect the Counter to each of the following OUT
PUTS of the instrument under test:
FRONT PANEL
1 MHz
5 MHz
100 kHz
REAR PANEL
1 MHz
5 MHz
100 kHz
Counter should display the correct frequency, plus
or minus the inherent 1-count error of the Counter.
3. OUTPUT VOLTAGES
Place instrument in operation (CONTINUOUS
OPERATION light on, ALARM light off).
Connect an RMSVoltmeterthrougha50-ohm Feed-
thru to front panel 5 MHz, 1 MHz, 100 kHz, rear panel
5 MHz, 1 MHz, and 100 kHz output jacks. Voltmeter
should indicate between 1.0 and 1.5 Vrms for each
frequency checked. Connect the same outputs to
the vertical channel of an Oscilloscope. Oscillo
scope display should be a clean sine wave.
4. HARMONIC DISTORTION CHECK
Harmonic distortion in the 5 MHz, 1 MHz, and 100
kHz output signals should be at least 40 dB down
from the 1 Vrms output. To perform this check, a
Spectrum Analyzer is tuned to the fundamental fre
quency and an amplitude reference is established.
The output frequency spectrum is then investigated
to determine fundamental-to-sideband amplitude
relationship at harmonic points of the fundamental.
Set instrument to normal operation mode
TINUOUS OPERATION light on).
Connect equipment shown in Figure 5-3.
CON-
5-2
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