Figure 4-2. Linearizing correction network.

TM 11-6625-524-14-4

The meter's input terminal will be shorted to ground when the voltmeter is switched

O F F . This helps to prevent electro-static build-up from damaging the meter move-

ment coil while in transit. It also facilitates in mechanically zeroing the meter

by removing all potentials from the meter movement coil.

1. DC output: For external monitoring purposes, a 1.0V (1mA m a x . ) linear output

voltage is provided at output connector, 5J2. When the external D C output 3 circuit

p h o n e plug (furnished as a standard accessory) is inserted, the i n t e r n a l 2K load

(5R1) at 5J2 is disconnected. The external monitor must provide the 2K impedance

load-and should be within ±1% accuracy to maintain rated' voltmeter specifications.

m. Power supply: The power transformer (2T1) has a

AC dual pri-

115V/230V

mary input. The full wave rectifier, 2CR1 and 2CR2, is connected to the center-

t a p p e d secondary. The rectifier's output is applied to the series regulator tran-

s i s t o r (2Q1). Reference voltage for both the series regulator transistor (2Q1) and

o u t p u t amplifier (2Q5) is provided by the reference amplifier (2Q3). A constant

c u r r e n t source, 2CR3 and 2CR4, maintains a constant bias at the reference ampli-

f i e r ' s base. The inverting amplifier (2Q2) will bias the series regulator tran-

s i t o r ' s base with an inverted reference voltage. A n adjustable voltage divider

a c r o s s the output amplifier's base permits adjustment of the series regulator's

o u t p u t . This electronically regulated power supply delivers a stable and virtually

r i p p l e free voltage source regardless of variations in power line voltage (103.5V

to 126.5V).

T o eliminate inter-action and possible oscillations between the various ampli-

f i e r boards circuits, local filtering is provided at the AC amplfying stages and

DC modulator driver.

L i n e a r i z i n g correction network.

4-4 Change 1