Model 618B Sect. IV Page 11
4-9 CHECKING AND TROUBLE SHOOTING cw output signal with a minimum of circuits oper-
THE RF GENERATOR SECTION ating. The output meter monitors the klystron
itself directly and if known to be operating properly
Satisfactory voltages obtained in the power supply may be used to check operation of the klystron
trouble shooting chart assure that with the excep- oscillator. The chart continues below and lists
tion of the klystron repeller voltages, the proper steps to determine if the rf power monitor and rf
operating voltages are applied to all portions of generator are operating; and, if not, where the
the signal generator. The 618B can generate a . trouble lies.
TABLE 4-5. RF GENERATOR TROUBLE SHOOTING CHART
~~~ ~
Check and Symptom I Possible Cause Remedy
I
~ ~~ ~ ~ ~
1. Note output meter indications with MOD. SELECTOR at OFF.
Meter inoperative; No supply voltage. Fuse F303 Measure supply voltage at R185;
no zero set: blown. should be approx. -3 volts from
ground. Replace F303 and deter-
mine cause for burnout.
Open meter M101. Disconnect meter and check con-
tinuity. Caution: 200 pamp movement
Meter pins upscale or Shorted or open component on Disconnect one side of meter.
downscale: one or other side of bridge to Measure supply voltage at R185;
cause unbalance. should be approx. -3 volts from
ground. Then measure the voltage
between each side of. the bridge to
determine side at fault. The voltage
at both midpoints on each side of
the bridge should be 1/2 the voltage
applied to the bridge from ZERO
SET potentiometer R185.
Meter erratic under all Unstable thermistor R202. Replace power monitor assembly
conditions : and recalibrate the attenuator as
described in para. 4-14.
Meter indicates rf power
output with the MOD. SE- Defective modulator tube V11: Replace V 113 and reset klystron
LECTOR in the OFF po- operating bias as described in
sition: step 7, Table 4-4.
2. Reading the front panel Unstable klystron operation, Check setting of repeller voltage as
output meter, check cw particularly at high frequency described in para. 4-12. If voltages
operation of klystron end of range due to poor kly- cannot be improved, check seating.
over the full frequency stron seating in cavity or im- Remove tube and clean up seat.
range: proper repeller supply volt- Using care not to scratch glass,
age settings, insufficient bear clean klystron grid rings. Reseat
current or weak klystron. as in para. 4-11.
Check beam current as in step 7,
Table 4-4.
Poor pulse output, cw N70, R173, R175, and R352 See para. 4-12.
output satisfactory: out of adjustment. |
ACEC
