Electrical Data

The new decades require an 80-volt negative-going pulse of 1 microsecond maximum rise time for driving purposes, somewhat lower than the driving voltage of previous units because of reduced stray capacities in the new layout. If faster rise time is available, somewhat less amplitude can be vised since the driving pulse is applied to a differentiating network of approximately 100 rami in series with 15,000 ohms. Each decade provides an 80-volt negative-going output step for driving another decade. The oscillogram of the output voltage in Fig. 3 shows the quality of the waveform.

The output staircase is provided for use when it is desired to operate remote indicating meters. The staircase waveform decreases in approximately equal steps from 135 volts at a count of zero to 55 volts at a count of nine. These voltages are the open-circuit voltages which are provided from a high source impedance of 700 kilohms. The staircase output can be operated into any passive load from short circuit to open circuit without affecting the operation of the decade. The high source impedance in combination with inevitable capacities will cause the shape of the steps to deteriorate at higher counting rates, but this is of no consequence since it is the d-c level during the display time that operates the remote indicating meters.

The reset connection on the decade is intended to be connected to ground either directly or through a low impedance. Resetting to zero can be accomplished in simple setups by mechanically opening this connection. Electrical resetting to zero can be accomplished by pulsing a low impedance placed in the reset lead with a positive pulse of 150 volts amplitude with I microsecond rise time and a slower decay time of

Fig. 3(af. Oscillogram of output voltages from decade. Upper trace is output waveform, lou er is output staircase.

140

m

1 DO

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+

50

40

it

-4-h

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8 0 1 COUNT

Fit;. 5(b). Explanatory drawing indicating voltage excursion and count relation. Plateaus correspond to counts.

at least 3 microseconds. Resetting to nine can be accomplished where desired with a negative pulse of similar amplitude and speed.

The decade requires a nominal plate voltage of -i-300 volts at 15 ma and filament supply of 6.3 vac at 1.2 amperes. All connections to the decades are made by means of a standard octal tube base type plug which serves as the mounting base.

GENERAL

To insure long life and a high degree of freedom from trouble, the resistors in the decades are all 5%-tolerance or better while all but the cathode capacitors are of the silver mica type. Computer type 5963 tubes are used. Production samples of the decades have been subjected to a wide range of tests. Samples have been operated continuously for 60 days at ambient temperatures above 70: C without failure. Other samples have been stored in temperatures of —60 C and, when removed, operated satisfactorily as soon as the tube filaments heated. Samples have also passed the 100-hour salt spray test defined in Specification QQ-M-151A and the shock and vibration tests defined in Specification M1L-T-945.

—Martin Willrodt

Fig. 3(af. Oscillogram of output voltages from decade. Upper trace is output waveform, lou er is output staircase.

0!21S

8 0 1 COUNT

Fit;. 5(b). Explanatory drawing indicating voltage excursion and count relation. Plateaus correspond to counts.

SPECIFICATIONS -hp-

MODEl AC-4A PLUG-IN DECADE COUNTER

COUNTING RATE: 120 kc maximum.

DOl/SIE PUiSF dfSOlUTION; S microseconds

INPUT VOITAGE; Appro*. 80 v negative Out» 1 ¿isec rise rim«, less amplitude required for faster rise time.:

OUTPUT VOLTAGE: 80 voir negative pulse to drive succeeding AC-4A Counter.

ftESET lo Reset lo lero by opining base pin connection, [b) Relet to nine by applying negative pulse.

STAIRCASE OUTPUT VOLTAGE: 13J volts ot count of rero, 5S volts of count of nine in 10 Heps. Internal resistance. 7CCK Operation of counter unaffected by load on staircase output.

POWEH SUPPLY: Filament—6.3 v +;10% ot 1.2 amp Plate—300 v it10% at IS ma (nominal).

DIMENSIONS^ deep * 1VV wide * SV's" high (overall).

MOUNTING; Standard; requires octal socket.

WEIGHT: t lb.; shipping weight appro*. 2 lbs.

PRICE: S45.00 f.o.b. Palo Alto. California. Quantity discount quotations available from the factory.

Data subject to change without notice

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