Sect. I' Page 6
6) Set the AMPLlTUDE control minimum to (max- 15) Switch the FUNCTION selector to TRIANGULAR
imum CCW) and move the voltmeter leads the to and note the voltmeter indication on (0.5 0-1 scale is
red OUTPUT terminals. "0 volts1'). Adjust R49 to reduce the dc voltage to
one-half of its initial value, then adjust R51 to remove
7) Adjust R65, located behind a hole the in panel the remaining dc voltage. The voltmeter should now
near the OUTPUT terminals, for an indication of indicate "0 volts1'.
"0 volts".
8) Set R119, located near V1 and T2, to the middle 16) Set the FUNCTION selector to SINE and adjust
of its range. R118 for a voltmeter indication of "0 volts".
9) Disconnect voltmeter the and connect equipment as
shown in Figure 4-1. 17) Verify the distortion the in output sine wave at
100 cps, first on the X10 RANGE with the FRE-
10) Set the FREQUENCY dial to 10, the RANGE QUENCY dial at 10, then on the XlOO RANGE with
switch to X10 (100 cps), FUNCTION selector to the FREQUENCY dial at 1. IL the distortion indi-
SINE, and the AMPLITUDE control for an output cations are not approximately identical, careful
of approximately 10 volts rms. adjustment of R119 will lower the 100 cps distortion
on the XlOO RANGE.
U) Adjust R49 and R51 to eliminate the points or
spikes at the ends of the Oscilloscope pattern. Ad-
justment of these controls will shift the output fre-
quenc y, you should follow the frequency shift with the 18) Connect the voltmeter COMMON lead to the
Distortion Analyzer. Adjust the Distortion Analyzer common junction of AMPLITUDE controls R93A
sensitivity as necessary to obtain a useful pattern and R93B (violet wire). Connect the DC volts probe
on the Oscilloscope. to the green wire on the opposite end of R93B.
12) Adjust R60 for minimum distortion as indicated
on the Distortion Analyzer. Repeat steps 11 and 12 19) Set the FUNCT ION selector to SQUARE and
until the distortion measured is at least 40 db below the RANGE switch X10. to Adjust R22 for a volt-
the output voltage (1%). meter indication of "0 volts1'.
13) Connect the voltmeter COMMON lead to the
common junction of AMPLlTUDE controls R93A and 20) Any dc between the red OUTPUT terminals with
R93B (violet wire). the AMPLITUDE control at minimum may be elim-
inated by adjusting R65 (behind the hole in the panel).
14) Connect the DC volts probe to the opposite of end This voltage should vary less than kO. 5 volts when
R93B. This is a green wire connected to the AM- the AMPLITUDE control is rotated through its full
PLITUDE control. range.
r \
f 1 r
\ , 1
-hp- MODEL 202A -hp- MODEL 330 -hp- MODEL 120 OR 130
LOW FREQUENCY DISTORTION OSCILLOSCOPE
FUNCTION GENERATOR ANALYZER
HORIZ.@
BD-S-38
Figure 4-1. Minimum Distortion Frequency and Adjustment hstrumentation |
ACEC
