Paragraphs 5-41 to 5-44
VACUUM TUBE VM
Figure 5-5. Test Setup for Hum and Spurious Modulation Performance Check
5-41. For Model 494A proceed as for Model 492A,
except, the generator to be used in figure 5-4 is to
be set at a frequency of 9.7 gc. The value from which
the attenuator dial reading is
be subtracted, is
-76.7 dbm for the Model 494A.
5-42. HUM AND SPURIOUS MOOULATIO
5-43. For Model 492A proceed as follows:
a. Connect test setup as shown in figure 5-5.
b. Set the generator to 8 gc and
modulation, 1000 pps.
c. Set the twt HELIX control to position 5, and
position the GRID BIAS control
d. Adjust the generator attenuator until the output
is indicated as a -20 db on the 4000.
e. Switch the generator to cw operation.
f. Record the reading on the 4000.
g. Take the difference, in db's, in the readings
in steps d and f and add to it 8 db. The sum of
these two numbers should be greater than 45 db.
5-44. For Model 494A proceed as for Model 492A,
except, the generator to be used in figure 5-5 is to
be set at a frequency of 12.4 gc.