Description; Accessory Features; Modifications - HP 333A Technical Manual

Model 333A/334A

1-1. DESCRIPTION.

1-2. The Hewlett-Packard Models
Distortion Analyzers are solid state
measuring distortion and ac voltages.
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.
333A and 334A

1-6. ACCESSORY FEATURES.

instruments for
The Models
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 - 1 1 .
1 - 1 2 , S p e c i f i c a t i o n C 1 0 - 3 3 4 A i s a s t a n d a r d
3 3 4 A D i s t o r t i o n A n a l y z e r m o d i f i e d b y p l a c i n g
the INPUT and OUTPUT terminals on the rear
p a n e l o f t h e i n s t r u m e n t . T h e r e a r t e r m i n a l s
a r e b i n d i n g p o s t c o n n e c t o r s a n d a r e i n
p a r a l l e l w i t h t h e f r o n t p a n e l t e r m i n a l s .
D u e t o t h e r e a r t e r m i n a l l e a d s , t h e s h u n t
c a p a c i t a n c e o f t h e i n s t r u m e n t i s i n c r e a s e d
by 20pF .
Paragraphs l-l to l-13
M o d i f i c a t i o n s
TM 11-6625-1576-15
Section I
1-3