Amplitude Accuracy Checks - Bal; Level Flatness Checks - HP 654A Operating And Service Manual

Section V
Model 654A
TEST OSCILLATOR
hp654A
AC- DC DIFFERENTIAL
VOLTMETER/DC STANDARD
hp74113
ADAPTER
hp10110
A
ADAPTER
hp10110A
SEE TEXT FOR
VALUES OF RI AND R2
Figure 5-2. Amplitude Accuracy Checks - BAL
5-13. 150 BAL AMPLITUDE ACCURACY.
a. Connect the equipment as in Paragraph 5-12a
except use 75 ohm resistors in place of the 67.5
ohms.
b. Set the 654A controls as in Paragraph 5-10b
except set IMPEDANCE to 150 BAL.
c. Perform steps c and d of Paragraph 5-12.
d. Add the two voltages; the total voltage should fall
between 1.213V rms and 1.237V rms verifying an
absolute level of + 10dBm, +/- 1%.
e. If the tolerances are not met troubleshoot the
instrument; the most likely problem would be the
150 ohm impedance network on the A4 Board.
5-14. 600 BAL AMPLITUDE ACCURACY.
a. Connect the equipment as in Paragraph 5-12a
except use 300 ohm resistors in place of the 67.5
ohms.
b. Set the 654A controls as in Paragraph 5-10b
except set IMPEDANCE to 600 BAL.
c. Perform steps c and d of Paragraph 5-12.
d. Add the two voltages; the total voltage should fall
between 2.424V rms and 2.474V rms verifying an
absolute accuracy of + 10dBm +/- 1%.
e. If the tolerances are not met troubleshoot the
instrument; the most likely problem would be the
600 ohm impedance network on the A4 Board.
5-15. LEVEL FLATNESS CHECKS.
5-16. 50 UNBAL FLATNESS CHECK.
a. Set the 654A controls as follows:
FREQUENCY dial 1
FREQUENCY RANGE X1K
OUTPUT LEVEL dBm + 10,0
IMPEDANCE 50 UNBAL
AMPLITUDE Adjust for OdBm
on 654A meter.
b. Connect the equipment shown in Figure 5-3; use
the 50 ohm thermal converter (Table 5-3) which
should be connected directly to the 654A UNBAL
output connector. (The parts required to build the
Reference Supply are shown in Figure 5-4).
TEST OSCILLATOR
hp654A
6544• 6.1695
THERMAL CONVERTER
SEE TABLE 5-3
DC NULL
VOLTMETER
hp
419A
III
REFERENCE
SUPPLY
SEE
FIGURE 5-4
_J
Figure 5-3. Level Flatness Checks
5-4