TM 11-6625-1576-15
Model 333A/334A
Section I
Paragraphs l-l to l-13
1-1. DESCRIPTION.
1-2. The Hewlett-Packard Models
Distortion Analyzers are solid state
333A and 334A
instruments for
measuring distortion and ac voltages.
The Models
333A and 334A include two control loops that auto-
matically tune both legs of a bridge circuit which re -
jects the fundamental when the rejection circuit is
initially set within the range of the loops. A high im -
pedance detector which operates from 500 Kc to greater
than 65 Mc provides the capability” of monitoring the
distortion of the amplitude modulation on an rf carrier.
1-3. Distortion levels of O. 1% to 1OO% full scale are
measured in seven ranges for any fundamental fre -
quency of 5 cps to 600 Kc.
Harmonics are indicated up
to 3Mc. The high sensitivity of these instruments re-
quires only O. 3 v rms for the 100% set level reference.
The distortion characteristics can be monitored at the
OUTPUT connectors with an oscilloscope, a true rms
voltmeter, or a wave analyzer. The instruments are
capable of an isolation voltage of 400 volts above chassis
ground.
1-4. The voltmeter can be used separately for general
purpose voltage and gain measurements. It has a fre -
quency range of 5 cps to 3 Mc (20 cps to 500 Kc for 300
pv range) and a voltage range of 300 pv to 300 v rms
full scale.
1-5. The AM detector included in the Model 334A is
a broadband dc restoring peak detector consisting of a
semiconductor diode and filter circuit. AM distortion
levels as low as O. 3% can be measured on a 3 v to 8 v
rms carrier modulated 30% in the standard broadcast
band, and lower than 1% distortion can be measured
at the same level of the carrier up to 65 Mc.
1-6. ACCESSORY FEATURES.
1-7. The accessory available with the 333A and 334A
Distortion Analyzers is a voltage divider probe, -hp-
Model No. 1000lA. The features of the probe are:
a. 10 megohms shunted by 10 pf, giving 10:1
attenuation.
b. DC to 30 Mc bandwidth.
c. 2% division accuracy.
d. 600 v peak input.
e. 5 ns rise-time.
1-8. OPTION.
1-9. Option 0l is a standard -hp- Model 333A or 334A
with a special meter and meter amplifier, compen-
sated to permit response to VU (volume units)
characteristics.
1-11. Modifications
1-12, Specification C10-334A is a standard
334A Distortion Analyzer modified by placing
the INPUT and OUTPUT terminals on the rear
panel of the instrument. The rear terminals
are binding post connectors and are in
parallel with the front panel terminals.
Due to the rear terminal leads, the shunt
capacitance of the instrument is increased
by 20pF .
1-3
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