Amplifier and Cathode Follower

TM 11-6625-542-14-1

grid, the output voltage will be returned to its established

R181. This voltage is then fed through cathode-follower

value of +225 volts. Capacitor C136 is included to

V393A in order to present a low impedance source.

improve the response-time of the circuit to sudden

Capacitor C170 filters the -15 volts output.

changes in output voltage. The screen grid of V124 is

5-8. Oscillator and Multipliers

connected to the unregulated power source through

(fig. 5-3)

R121; therefore a small ripple voltage will appear at the

The oscillator is a conventional electron-coupled, crystal-

screen. This ripple will be amplified through V124 and

controlled oscillator.

The oscillator is designed to

fed to both the grid and the plate of V107A. Because the

generate a nonsinusoidal rf voltage at a frequency of 1

grid and plate voltages are 180 out of phase, a

megacycle. The crystal is incorporated in the oscillator

cancellation of the ripple voltage occurs at the cathode.

circuit to maintain a constant frequency within a

Thus, the ripple on the +225 volt bus is reduced to a

tolerance of +10 cycles. The crystal is installed in a

negligible value.

thermostatically controlled oven to minimize frequency

5-6. +350 Volts Supply

drift. Adjustable capacitor C205, connected across the

The +350 volts supply is fed from a secondary winding

crystal, permits slight adjustments to be made in

across terminals 7 and 8 of T101. This supply functions

oscillator frequency. The output waveform from the plate

the same way as the +225 supply. The rectified, filtered

of V200B is fed to the grid of V204B through C210 and to

output from the 115 volts ac secondary winding is added

the grid of V200A through RC network R203, C203. The

to the input of the + 225 volts supply to furnish the power

RC network is incorporated to increase the risetime of

required for the +350 volts regulator.

the signal on the grid of isolating cathode-follower V200A

so there is coincidence of pulses on the grid of V204B

5-7. Bias Voltages

and V200A.

Conventional voltage amplifier V204B

Bias voltages for the electron tubes are derived from the

provides a voltage gain of about two and one-half times

--150 volts supply. A voltage-dividing network consisting

the input voltage. Inductor L207 is a peaking device

of R174 and R176 across the output of the --150 volts

incorporated to improve the risetime of the output

supply drops the voltage at the junction of the two

waveform.

resistors to -8 volts. Capacitor C174 filters this output.

The --15 volts supply is set by voltage divider R180,

Figure 5-3 Oscillator and multiplier, schematic diagram.

(Located in back of manual)

operates when any one of the SINE WAVE pushbutton

5-9. Amplifier and Cathode Follower

switches is actuated.

Triode V204A is biased at cutoff by voltage divider R213

5-11.

10 MC Multiplier

and R214. Coupling capacitor C216, in conjunction with

L116, forms a differentiating circuit which shapes the

The grid circuit of V234 is inductively coupled to the plate

output wave of V204B into sharp pulses on the grid of

tank circuit of the 5-megacycle multiplier through the rf

V204A. The positive pulses are taken from the cathode

transformer described above.

The grid circuit is

as 1-microsecond markers. The output is then fed to

composed of L227, C227 and C229 and forms a series-

S710 and to the 5-megacycle sine wave multiplier.

resonant circuit tuned to 10 megacycles. This signal is

amplified by V234 and fed to the tuned plate circuit.

5-10.

5 MC Multiplier

Inductor L234 is the primary of an rf transformer and is

Capacitor C222 and resistor R222 develop a grid-leak

tuned to 10 megacycles. Like the 5-megacycle circuit

bias of -4 volts. This if sufficient to operate V224 as a

described above, the secondary (L237) of the rf

class C amplifier. The plate tank circuit of V204B

transformer is tuned to a multiple of the primary

resonates at 5 megacycles. Inductors L224 and L227

frequency (in this instance 50 megacycles) and is

are the primary and secondary, respectively, of an rf

sustained by it. Like the 5-megacycle signal, the 10-

transformer. Inductor L227 resonates at a multiple of the

megacycle signal is link-coupled to the output switch.

primary frequency (10 megacycles) and is sustained by

The 10-megacycle multiplier operates only when the 10

the primary excitation. The 5-megacycle sine wave

MC or 50 MC pushbutton is actuated.

developed across the tank circuit of V224 is link-coupled

to output switch S710. The 5-megacycle multiplier

5-2