Wavetek 3000 Instruction Manual page 203

OPTION -3
OPERATION CHECK
KI
Figure
moving the external RF signal from the
instrument .
The negative output from ICI also turns
off Q2, thus removing the short on pin
7 of timer IC2 . This allows the timer
to operate as an
astable oscillator .
The output,
pin 3 of IC2, then varies
between 0 and 7 volts . This causes Q3,
the LED driver, to supply current inter-
mittently to the front-panel UNLEVELED
light, causing it to flash .
After the RF overload is removed, IC1
can be unlatched by momentarily removing
AC power to the instrument .
The following procedure is recommended
to insure proper operation of the pro-
tection device . The top cover must
be removed from the instrument .
With the instrument operating normally
in the CW mode, set the output level to
+5 dBm. Connect a 50 ohm detector to
the output of the signal generator . The
DC output of the detector should be mon-
itored on a suitable oscilloscope . Set
the output frequency to 100 MHz .
The circuitry in the M35-1 is
checked
by pushing the momentary switch located
on top of the module . This switch
lowers the trip level of the
module .
While holding down
the switch slowly
increase the output of the unit
using
8/3-1 . Block Diagram
the VERNIER until the M35-1 trips . This
causes the circuit
breaker to open
and latch, the UNLEVELED light to flash,
and the detected output
displayed on
the oscilloscope
to go to zero . The
circuit breaker can then be
reset by
momentarily turning the AC POWER switch
off . The
M35-1 should have tripped at
+7 .5 dBm _+1 dB . Perform the same test
at 500 MHz . It should then trip at an
output level of +10 .5 dBm +2 dB .
The above procedure, while not a complete
performance check, is considered adequate
for most applications . Additional tests
can be performed as desired . For example,
insertion loss
and VSWR can be checked
in the same manner as any passive device .
Also, if available, a high power RF sig-
nal source, set for an output of slightly
over .7 W can be used to verify circuit
breaker operation .
MAINTENANCE
RF
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The only maintenance for the RF circuit
breaker is periodic
testing to insure
its operation .
If a malfunction occurs,
a trouble can be localized and repaired
with the aid of the theory of operation
and the schematic .
If the problem is a
defective monitor diode, care should be
observed to keep
lead length and posi-
tion the
same as the original
diode .
Option
3 can be
factory or field in-
stalled . The following procedure should
be followed for field installation .