1b-46
Operation Reference
Function
6. 1 kHz + EXT DC
Press
1 kHz + EXT DC
to configure the MOD INPUT/OUTPUT port as a dc-coupled input for
modulating the carrier along with the internal 1 kHz source.
(Refer also to "3. EXT AC EXT DC" for further information about operation and acceptable
ranges.)
NOTE
1 kHz + EXT AC, 400 Hz + EXT DC, and 400 Hz + EXT AC are available only
via GPIB.
Setting the Modulation Level When modulating with both an internal and external
source, the level of the external source should not exceed 0.5 V peak or 0.5 Vdc. This level
will provide one half of the displayed modulation. To set modulation to the level you desire,
set the displayed modulation to two-thirds of the desired setting. The external source, set
to 0.5 V peak or 0.5 Vdc, will provide the additional one-third of the desired setting
(one-half of the instrument’s setting).
For example, to set up the modulation for 3 kHz of FM deviation, set the instrument for 2
kHz of FM. The external source, set to 0.5 V peak, will provide another 1 kHz of deviation.
If the external source is set to less than 0.5 V peak, the modulation level provided by the
external source will be less than one-half of the displayed modulation. The following
equation may be helpful for determining the appropriate modulation level setting for the
instrument when the level of the external source is less than 0.5 V.
Where:
• A = Actual modulation level
• E = External source level
• D = Displayed modulation level
For example, to set up for 3 kHz of FM deviation with an external source set
to 0.3 V peak, the instrument’s displayed modulation level would be:
7. MOD INPUT/OUTPUT
This port outputs a 1 Vpk (into 600 ohms) audio tone when an internal modulation source
is selected. When an external modulation input is selected (
EXT AC
,
EXT DC
or
1 kHz + EXT
DC
), it provides the input for a 1 Vpk (into 600 ohms) audio source. (Refer to the preceding
table for acceptable frequency ranges.)
A
1
E
+
-------------
D
=
3 kHz
1
0.3 V
+
----------------------
2.3 kHz
=
Summary of Contents for 3847A
Page 12: ...xviii Contents ...
Page 18: ...1 6 Operation Quick Overview ...
Page 20: ...1a 2 Operation Examples ...
Page 48: ...1a 30 Operation Examples Signaling a Numeric Type FLEX Pager Option 1EP Only ...
Page 102: ...1b 54 Operation Reference Function ...
Page 114: ...1c 12 Operation messages Service Messages ...
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Page 163: ...2 2 GPIB Programming ...
Page 167: ...3 4 Installation Connecting AC Power Figure 3 1 Replacing the Fuse ...
Page 168: ...3 5 Installation Connecting AC Power Figure 3 2 Power Cable and Mains Plug ...
Page 173: ...3 10 Installation Shipping the Signal Generator ...
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Page 188: ...4 2 Specifications ...
Page 198: ...5 10 Service Safety Notes ...
Page 200: ...5a 2 Theory of Operation Figure 5a 1 8648A Simplified Block Diagram ...
Page 201: ...5a 3 Theory of Operation Figure 5a 2 8648B C D Simplified Block Diagram ...
Page 218: ...5a 20 Theory of Operation A30 Pager Encoder 8648A Option 1EP ...
Page 220: ...5b 2 Troubleshooting Information Troubleshooting Checklist Troubleshooting Checklist ...
Page 224: ...5b 6 Troubleshooting Information Power Supply Distribution ...
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Page 230: ...5b 12 Troubleshooting Information Power Supply Distribution ...
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Page 232: ...5b 14 Troubleshooting Information Power Supply Distribution ...
Page 242: ...6 2 Replaceable Parts Assembly Replacements ...
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Page 244: ...6 4 Replaceable Parts 8648A Replaceable Parts ...
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Page 250: ...6 10 Replaceable Parts 8648B C D Replaceable Parts ...
Page 251: ...6 11 Replaceable Parts 8648B C D Replaceable Parts ...
Page 318: ...7 62 Adjustments Agilent Service Support Software ...
Page 413: ...8 95 Performance Tests 8648B Test Record ...