Frequency-Time Recorder - TM-11-6660-204-250033

TM 11-6660-204-25

creases resistance and a more negative voltage

itors have a low reactance to ripple frequencies

increases resistance. Control amplifier tube V410

and practically the entire voltage change appears

controls the amount of voltage supplied to the

across resistor R410. This voltage change either

grid of tube V409. The cathode of tube V410 is

adds to or subtracts from the grid voltage sup-

connected to a constant reference voltage, which

plied by potentiometer R412, so this circuit re-

is supplied from negative voltage reference tube

duces the 120-cycle ripple voltage as well as the

V411. Because the cathode voltage is held con-

changes due to line voltage or load conditions.

stant, only the grid voltage affects operation of

Capacitor C406 is the output filter capacitor.

this circuit. The grid voltage is supplied from a

c. The negative regulated power supply (fig.

bleeder network across the regulated negative 175

218) furnishes a constant negative 175 volts re-

volts determined by the position of the arm of

gardless of variations in the input voltage or load

potentiometer R434. When the line voltage in-

conditions.

creases or the load current decreases, the voltage

across the bleeder increases. A portion of this

(1) Rectifier tube V408 functions as a con-

voltage change, determined by the setting of po-

ventional full-wave rectifier. This circuit is shown

tentiometer R434, is amplified by tube V410 and

as a block in figure 218; for individual compo-

applied as a negative swinging grid voltage to

nents, refer to figure FO6. Fuses F403 and F404

tube V409. This decrease of grid voltage causes an

are connected in series with the plate leads of

increase in the effective plate to cathode resist-

rectifier V408 for overload protection. Capacitors

ance and increases the voltage drop across tube

C415 and C416, with choke coil L402, comprise a

V409, This increase in voltage drop, which is al-

pi one-section filter for the unregulated supply.

most equal to the original voltage rise, returns the

Resistor R421 is a bleeder resistor which dis-

grid bias value of tube V410 to the original input.

charges the filter capacitors when the equipment

The action of the regulator is so rapid that it can

is turned off. The negative series regulator tube is

be considered to be instantaneous. Capacitor C418

a twin-triode type which obatins its plate voltage

provides a low reactance path to the grid of tube

from the unregulated supply, through parasitic

V410 for any rapid changing voltage or ripple

suppressors R424 and R425 in one plate circuit,

voltage. This voltage change either adds to or sub-

and parasitic suppressors R426 and R427 in the

tracts from the grid voltage supplied by poten-

other plate circuit, The cathode is returned to

tiometer R434, so this circuit tends to minimize

circuit ground. The negative 175 volts is obtained

ripple voltage in addition to rapid changes in line

from the center tap of the plate winding. Resis-

voltage or load conditions, Capacitor C420 is the

tors R428 and R429 are grid-current limiting re-

output filter capacitor and bypasses any hf volt-

sistors, A voltage divider which consists of resis-

age component.

tors R433 with potentiometer R434 is placed be-

tween the regulated negative 175-volt output and

d. A positive 500-volt unregulated voltage sup-

circuit ground. The voltage of potentiometer R434

ply is obtained by taking the unfiltered and unreg-

is applied to the control grid of negative control

ulated voltage from the filament of positive sup-

amplifier tube V410. The screen-grid voltage" for

ply rectifier tube V401. This voltage is applied

this tube is obtained from a voltage divider con-

through resistors R417 and R418 to the control

sisting of resistors R430 and R431 and the nega-

winding of balancing motor B501. Filtering is

tive voltage reference tube V411 to ground, con-

accomplished through capacitor C408 and the in-

nected across the regulated negative 175-volt sup-

herent inductance of the motor winding.

ply. The plate of tube V410 is directly connected

e. A filament burn-out neon indicator lamp

to the grids of tube V409 through grid-current

(E401) is provided for pen-lifter control tube

limiting resistors R428 and R429, and controls the

V407. This lamp is connected across the filament

operation of this series regulator tube. Negative

so it is normally short-circuited and does not indi-

voltage reference tube V411 is a cold cathode-type

cate until the tube filament opens. A similar indi-

gas voltage regulator tube, which normally oper-

cation is provided for tubes V305, V304, V309,

ates at 87 volts and is connected to the cathode of

V308, V306, and V307 in the signal converter cir-

tube V410 to provide a constant reference voltage

cuits by neon indicator lamps E301 through E306.

for comparison with the grid voltage of negative

control amplifier tube V410.

2-18. Frequency-Time Recorder

(2) Series regulator tube V409 functions as a

The purpose of the frequency-time recorder is to

variable series resistor, which is controlled by its

make a continuous record of the frequencies re-

grid bias voltage. A less negative grid voltage de-

2-22