Figure 6-11. Meter rectifier circuit, Spectrum Analyzer TS-723D/U.

TM 11-6625-255-14/TO 33A1-13-170-1

input of V 12. Its function is to improve frequency

vides conduction for the negative portion of the ac

r e s p o n s e and to stabilize the operation of the

cycle. Tube V14A (CR2 of TS-723D/U) provides

vtvm circuit. The amount of feedback voltage es-

conduction for the positive portion of the ac cycle.

tablishes the gain of the voltage amplifier circuit.

Meter M1 is a milliammeter calibrated in R.M.S.

During the positive portion of the ac cycle, the

V O L T S and DECIBELS. The sensitivity of the

feedback loop is completed through R71. During

meter is 1,000 ohms per volts, or 1 milliampere for

the negative portion of the ac cycle, the feedback

full-scale reading. Capacitor C31 filters out the ac

loop is completed through R70. The amount of

component appearing across the meter terminals.

feedback voltage applied to the grid of V12 is

d. A negative feedback loop is obtained at the

g o v e r n e d by network R61, R62, and R63. The

o u t p u t of V14 (CR1 and CR2 of TD-723D/U).

variable resistor R62 VM GAIN is used to adjust

This negative feedback voltage is fed back to the

Figure 6-10. Voltage amplifier and meter circuit, simplified schematic diagram.

Figure 6-11. Meter rectifier circuit, Spectrum Analyzer TS-723D/U.

6-10