HP 3585A Service Manual page 57

Model 3585A
(The 3585A's equivalent noise bandwidth is approximately 1 .2
times the 3 dB bandwidth established by the Resolution Band­
width setting. The 3 dB bandwidth has a specified tolerance of
± 2007 0 and must, therefore, be measured to obtain accurate
results.)
1. The IF Output goes to its full-scale level (270 m V to 190 m V )
during A utomatic Calibration cycles.
2. The Video Output level is + 10 Vdc during A utomatic calibra­
tions.
3. I f the video amplitude is more than ten divisions below the
Reference Level, the Video Output will go negative. Maximum
negative output levels are typically as follows:
V I DEO
OUTPUT
�
NOTES
dB/DIV Maximum Negative Output
10 - 0. 5 Vdc
5 - 10.5 Vdc
- 13.5 Vdc
2 or 1
The VIDEO OUTPUT supplies a dc output voltage (prior to peak
detection and digitizing) that is proportional to the "A" Trace video
amplitude on the CRT screen. The Video Output is scaled to one volt
per division, and the nominal output level ranges from + 10.0 Vdc at
the Reference Level to 0.0 Vdc at ten divisions below the Reference
Level. The output resistance is 1 kilohm, nominal. The output is
diode clamped to ± 1 5 Vdc and is internally fused at 62 mA, N.B.
The Video Output can be applied to an external analog-to-digital
converter or digital voltmeter to obtain higher amplitude resolution
than is provided by the CRT readouts; it can be used in conjunction
with the "X" and "Z" PLOTTER outputs to make oscilloscope
plots or X-Y recordings of the non peak-detected video signal; and,
when connected to a high-impedance headset or amplifier through a
coupling capacitor, it can be used to monitor the audio on
amplitude-modulated carrier.
logarithmic, the audio obtained from the Video Output is quite
distorted although intelligible enough for monitoring purposes.)
Operation Overview
(Since the video amplitude is
an
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