Wavetek 3000 Instruction Manual page 179

OPTION 1A
another voltage divider in the "0 .1 dB
Program Select" circuit . Then, rear-
panel .8- .4- .2- .1 BCD input
activates
more FET switches to select voltage points
on this divider which correspond to 0 .1
dB steps . The output of the FET switches
is connected through Meter Board relay
KIto the +10 dBm/0 dBm level circuitry .
If amplitude modulation input is applied
to Meter Board, the modulation signal will
be superimposed on the DC signal applied
to voltage divider in the "1 dB Program
Select"
circuit, and thence on to the
"0 .1 dB Program Select" circuit . The
combined modulation/level program output
voltage is applied to
Output Amplifier
through the +10 dBm/0 dBm level circuitry .
MAINTENANCE
No calibration or maintenance should be
required for this option, other
than
that described in previous sections of
this manual for calibration of the Meter
Board . However, if a malfunction of
some kind
should make it necessary to
repair the
boards, they can be safely
probed with a high impedance probe such
as a scope or DVM .
A logical trouble-
shooting procedure of
isolating the
fault should be followed . The integrated
circuits, which are most
vulnerable to
accidental shorts,
are all in sockets
for easy replacements .
SCHEMATICS AND PARTS LISTS
This section contains the wiring diagram,
schematics, and parts lists for Option 1A .