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Model 5065A
Circuit Diagrams, Theory, and Maintenance
c.
Connect a reference 5 MHz to INPUT A and the
5065A 5 MHz output to INPUT B.
d.
Set "Zero-Oper-Full" front panel mounted toggle
switch to "Zero". Adjust "Zero Scale" control for a zero
scale trace on recorder.
e. Set switch to "Full" and adjust "Full Scale" control
for a full scale trace on recorder.
f.
Check both "Zero" and "Full Scale" outputs and
readjust if necessary.
g. The recorder will now provide a continuous rec
ord of frequency comparison and will be automatically
reset when the recorder pen reaches zero or full-scale
position.
h. With the recorder set for 1 volt full scale and
1 in./ hr., the phase difference recorder will be 0.2 ^isec
full scale with 5 MHz inputs. See Figure 3-4 for an exam
ple of a frequency difference measurement under these
conditions.
3-19.
OPERATION WITH TIME STANDARD
OPTION 001 (or 003)
3-20.
Option 001 provides Model 5065A with a one
pulse-per-second clock output. The divider drive is an
internally connected 1 MHz signal from A6 frequency
Divider Assembly. TIME DELAY controls are located on
the A5 Assembly and can be seen with the top cover
removed. The TIME DELAY six thumbwheel switch con
trols the phase of the clock-pulse output from 1 micro
second to 1 second with respect to an external reference.
The 0-1 microsecond TIME DELAY screwdriver adjust
ment allows fine adjustment over any 1 microsecond
portion of the thumbwheel settings.
3-21.
The time standard option includes a 24 hour, LED
digital clock assembly (A19) which indicates time in
hours, minutes and seconds. The SYNC button on Divider
Assembly A5 enables the instrument to synchronize toan
external reference standard. The digital clock is set by
pressing the SET pushbutton, SLOW/FAST switch and
HOLD pushbutton (located on rear of clock).
3-22. SETTING THE CLOCK PHASE TO AN
EXTERNAL CLOCK
3-23. The phase difference between the 5065A 1-PPS
output and an external reference clock may be set to any
desired point between coincidence and 1 second by
using the following procedure. The technique used will
depend on the Model 5065A application and individual
user requirements.
3-24. Automatic Synchronization
3-25. To automatically synchronize the 1-PPS output
pulse and the internal clock drive with an external 1-PPS
reference, proceed as follows:
a.
Remove the top cover for access to TIME DELAY
controls.
b.
Rotate the 0-1 sec TIME DELAY control maxi
mum cw for minimum delay (do not overtighten).
c.
Set the TIME DELAY thumbwheel switches for
the desired time delay of the clock pulse. The thumbwheel
switches read directly. However, there is a 9-11 yusec built-
in delay in the digital divider circuit which should be
added to the time-delay calculation.
d.
Connect the reference pulse to the rear SYNC
INPUT jack (must be greater than +5V with less than
50 nanoseconds rise-time and a width greater than
0.5 fisec.
e. Press SYNC pushbutton on A5 Assembly and
hold down at least 1-second. The next tick of the clock
output will be delayed according to the setting of the
thumbwheel switches (plus the 9 to 11 /usec built-in delay).
For more precise adjustment of time delay, the 0-1 jusec
TIME DELAY provides continuous delay adjustment from
0-1 jusec.
f.
When the clock pulse is synchronized, the digital
clock will advance in synchronism with the instrument
1PPS.
g.
For a delay of less than 10 jusec, the thumbwheel
switches are first set at 999,999. Then the thumbwheel
setting is decreased as required and final adjustment is
made with the 0 to 1 /^sec TIME DELAY control. Use an
arrangement like that of Figure 3-8 to accurately measure
time intervals between the two 1-PPS pulses. For short
delay intervals, use an oscilloscope. For longer delay
intervals, use the optional counter arrangement.
3-26.
Manual Synchronization
3-27.
If the reference pulse does not meet the require
ments for sync operation (>+5V, <50 nanosecond rise
time, and width >0.5^sec), use the technique of Figure 3-8
to measure time intervals. Set time delay of the 5065A
1-PPS output as required with the TIME DELAY thumb
wheel switches and 0-1 yusec control. For small delay
intervals, use an oscilloscope. For larger delay intervals,
use the optional counter arrangement.
3-28. Setting the Clock
a.
Remove top cover.
b. Set hours, minutes, and seconds by placing the
SLOW/FAST toggle switch at FAST, and momentarily
depress the SET pushbutton for rapid advance of the dis
play. Place toggle switch to SLOW and press SET push
button for slow advance of the display.
c.
Set seconds on the display slightly ahead of the
reference clock, and then press the HOLD pushbutton.
Release HOLD pushbutton when reference clock time is
identical to the digital clock.
d.
Replace the instrument top cover.
3-9
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