HP 4194A User Manual

• The HP 4191 A only covers the higher
frequency range of 1MHz to 1GHz.
© The HP 4192A only covers the lower
frequency range of 5Hz to 13 MHz.
• The HP 4193A only measures Z- 0, and
has a spot oscillator level.
The HP 4194A with the HP 41941A/B, how 
ever, can measure grounded circuits and can
evaluate the negative input impedance of oscil 
lator circuits with the following features.
♦ Wide frequency coverage of 10kHz to
100MHz with an accuracy of 1.5% to 3%
for Z-6, plus R-X measurements.
« Variable OSC level and OSC level sweep.
HP 41941A/B probe to the location where the
crystal is to be installed.
o Vcc Effects on Input Impedance
Confirm that the oscillator works at the
Vcc value as designed. Vcc margins can be
evaluated by varying the Vcc and observing the
value of R vs. Vcc on the display.
o Oscillator Input Impedance as a Function of
Frequency (Figure 6)
This measurement is for evaluating negative
impedance characteristics in detail at frequen 
cies around the designed oscillation frequency.
The frequency range of oscillation can be found
by determining the frequency range over which
the input impedance is negative.
« The 4194A ’ s Auto Sequence Program
(ASP) function enables automatic evalua 
tion without the need for an external
computer.
Measurement Specifics
To determine whether an oscillator operates
at its specified frequency, voltage (Vcc), and
output level, the items discussed in the follow 
ing paragraphs are required when evaluating
oscillators.
Connect an external DC power supply (Vcc)
to the oscillator circuit (without a crystal in 
stalled), as shown in Figure 2, and connect the
o Oscillator Input Impedance as a Function of
Input Level (Figure 7)
You can substitute the input level charac 
teristics for the output level characteristics of
an oscillator. Use the HP 4194A ’ s oscillator
level sweep function to determine the dependen 
cy of negative input impedance on input signal
level.
The HP 4194A is also cost effective for
evaluating the resonators used in oscillator cir 
cuits. Figure 3 shows an ASP program for
automatically measuring the frequency and OSC
level (input signal level) characteristics of an
11.904 MHz crystal oscillator. This ASP pro 
gram performs sequential measurements as
follows:
10 I OSCILLATOR EVALUATION ttMt
20 RST
30 CMT'IMP CHARACTERISTICS OF CRYSTAL-
40 ASC2iSWM2;R0-.5 I R0-DEFAULT OSC LEVEL
50 CENTER- 16.667 MHZiSPAN-50 KHZ
50 OISP ’ CONNECT CRYSTAL RESONATOR"
70 PAUSE
60 SUTRG
30 AUTOiDISP-OSC- ’ ,R0
100 BEEP
110 PAUSE
120 CMT ’ R/POWER-OSC CHARACTERISTICS ’
130 IMP2jSWP3iASC1
140 R1-I6.65E+6 IR1-OSC FREQ(HZ)
150 FRE0-R1iUNIT0iDISP "FREQ-" ,R1
160 START-0. 05 ViSTOP-0.2 V
170 R2-0.001 IR2-P0UER LIMIT(U>
180 SUTRG
190 B-X*X/A;AUTO IB-POUER(U)
200 MCF3iCUR2(LCURS-R2<R3-LCURSL IR3-MIN OSC LEVEL
220 MKR-R3iR4-MKRA IR4-RESISTANCE AT R3
230 DISP ’ SETUP 41941 A/B & OSCILLATOR-
240 BEEP
250 PAUSE
260 FNC3iIMPZiSUPI|PUS2
270 ITM21DPA IiOPB0 „
280 oisp -OSC- ’ ,R3iOSC-R3 Figure 3. ASP Program List
290 CENTER-RIi SPAN-50 KHZiUNITI
300 CMT ’ R-FREO CHARACTERISTICS OF OSCILLATOR-
310 SUTRG
320 AUT0 i MCF3 i CURI iLCURS — R4
330 DISP-PRESS<CONT> TO R-OSC ’
340 BEEP
350 PAUSE
360 SUP3jFREQ-R1jCENTER-R3 UjSPAN-.1V
370 CMT-R-OSC CHARACTERISTICS OF OSCILLATOR *
380 SUTRG
390 AUT0iMCF3iCUR1 iLCURS — R4jDISP "FREQ- ’ ,RI
400 ENO
-2-

HP 4194A Specifications

General

Brand	HP
Model	4194A
Category	Measuring Instruments
Language	English