500-Kc If. Filter FL901

p a r a l l e l - t u n e d circuits in cascade and

from bandpass filters Z401, Z402, and

c a p a c i t i v e l y coupled. Only three of the

Z403. Jack J402 is a test point for mesaur-

t u n e d circuits are shown in figure 10.

ing the dc bias and rf voltage on the grid of

The 500-kc if signal is coupled from

V401A.

third receiver mixer V401A through

33. 500-Kc If. Filter FL901

F L 9 0 1 to first 500-kc if. amplifier V501

T h e 500-kc if. filter consists of nine

Figure 10. Third receiver mixer and third oscillator V401, schematic diagram.

Section VI. 500-KC IF. AND AUDIO AMPLIFIER SUBUNIT

34. First 500-KC If. Amplifier V501

J503 is provided for injecting a test signal

f o r troubleshooting. The control grid is

connected to the if. avc bus through isolat-

a. First 500-kc amplifier V501 is the

ing resistor R501. Resistor R502 provides

f i r s t of three if. amplifiers that amplify

cathode bias for V501 and capacitor C507

the 500-kc output of V401A (para 32). When

is a bypass capacitor to ground. Capacitor

this equipment is used for receiving, the

C504 provides a low-impedance path for rf

500-kc third if. is fed from 500-kc if.

signals from the screen grid to the cathode.

filter FL901 (fig. 10) through plug P8 and

b. Plate voltage is supplied from the

jack J502 to the control grid V501. Jack