HP 8648 A/B/C/D - Changpuak.ch

Modulation Source
Note
5. EXT AC
EXT DC
6. lkJ3z + EXTDC
Note
1 b-52 Operation Reference
&!GJ) recalls the frequency/waveform combination that was set up
earlier. For example, an instrument is configured so the AM state is
set up with a 2 kHz sine waveform, the FM state is set up with a
500 Hz square waveform, and the 4M state is set up with a 5 kHz
triangle waveform. Then pressing either IAM), (FM, or @KJ will set
the instrument to that modulation type with the frequency/waveform
combination to which it was previously set.
If another key (for example, C-1, @KKKiZJ and so forth) is
pressed after a frequency and waveform combination is set, pressing
the @iYiiZKj key once makes the (INT) active. Subsequent key
presses toggles the instrument through its waveform choices.
Press one of these keys to configure the MOD INPUT/OUTPUT port as
an ac- or dc-coupled input for modulating the carrier.
Calibrated modulation requires an audio source of 1 Vpk into
600 ohms. For audio source frequencies of less than 10 kHz, a HI or LO
indicator will appear in the second line of the MODULATION display
when the level of the source is not within approximately f5% of
1 Vpk.
Acceptable Frequency Ranges for an External Audio
Source
Modulation Coupling Range
FM EXT AC 1 Hz to 150 kHz
EXT DC DC to 150 kHz
4M EXT AC 20 Hz to 10 kHz
AM* EXT AC 1 Hz to 25 kHz
AM* EXT DC dc to 25 kHz
* AM bandwidth degrades at carrier frequencies below 1.5 MHz
and is not specified.
If you press [-DC) while the instrument is already in external dc
mode and the FM is on, then the instrument will perform a dc FM
calibration. The calibration takes approximately one second. During
the calibration the following message appears on the display: DCFM
calibrationinprogress.
Press (1 kHz t 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.)
1 kHz + EXT AC, 400 Hz + EXT DC, and 400 Hz + EXT AC are
available only via HP-IB.