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Model
890214
Operation
Time Base 10 MHz Input and Time Base 10 MHz Output
p v m i q
Do no1
apply grrafcr lhan 2OVpcak (ac
+
dc)
into the TIME BASE
10
MHz
INPUT or damagc
to
the instriimenl may resirlt.
Do not
apply
grcaler rhan 3 Vdc or greatm than +20 dBm info Cht> TIME
BASE I O M f f z
OUTPUT
or darnage to thc insirirmcnt may rcsirlf.
Description
Time Base 10 MHz Input. Provides an input for an external 10 MHz time base reference. This
input is ac coupled and requires an input signal level greater than 0.5 Vpp. The input impedance is
approximately
500i2.
The time-base circuitry of the Measuring Receiver automatically switches
to
the external time base
when an external time base of sufficient amplitude is applied.
When using an external time base reference, the acccuracy of all measurements depends on the
accuracy of the external reference. Frequency-related measurements are most noticeably affected
by time-base innacuracy.
To determine whether the Measuring Receiver has actually switched in the externally applied time
base, select 15.1 SPCL. If an external time base is being used, the display will show a
1.
If the internal
time base is being used, the display will show
a
0.
If the Measuring Receiver is using the internal, Option 002 time base, you can determine whether
the time base oven is warm enough to create a stable source by selecting 15.0. The display will show
a 0 if the time base oven is adequately warm. The display will show Error
12
if the time base is cold.
To drive several instruments from a single external reference, simply use a BNC tee at the Measuring
Receiver's TIME BASE 10 MHz INPUT.
If the internal time base fails, an external time base may still be used. Connect the external time base
to TIME BASE 10 MHz INPUT, then switch the instrument's POWER switch to STBY and back to
ON.
Time
Base
10
MHz
Output. (This output is available only with the high-stability reference, Option
002.)
Provides an output for the internal 10 MHz reference. The output is a
500, TTL
compatible
output (OV to greater than 2.2V into an open circuit).
When driven from an external reference, the Measuring Receiver outputs the internal reference (not
the external input signal). TIME BASE 10 MHz INPUT provides an input for an external 10 MHz
time base reference. This input is ac coupled and requires an input signal level greater than 0.5
Vpp.
The input impedance is approximately
500Q.
rev.
I6JUNEY6
3-3
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