Western electric 22 d schematic

Page 1

Wemm Electric Company
No.22-D SPEECH INPUT EQUIPMENT

5
l. Amplifier-control arm Carrying Case with Cover 5. Ac Power Uni! with Cord and Plug 9. HA rrammmer Attachment
2. Amplifierrconfral Unit a, 539 Type Microphone 10. 442A Jack and 712A Adapler
a. Power Supply Carrying Case Wm. Cover 7. xsrrzooo Transmmer Cover 11. Microphone Plug:
4. Buflery Rock Assembly with Cord and Plug 3 24A Transmiller Mourning 12 .7133 Cordage

l 3. IOOZF Headset

Figure 19 - Componenls of lhe 220 Speech lnpul Equipment

220 SPEECH INPUT EQUIPMENT

Use - A compact portable speech input system, light in
weight and designed to provide complete pick-up facilities
both for established remote and for on~therspot broadcasts.

Description - It consists of a combination amplifier and
control unit with a carrying case, and either a power unit
for a-c operation or a battery holder for battery operation or
bath, as specified, with a carrying case and a power supply
cord. The long and dependable service experienced with
this high quality light weight equipment has made this unit
a favorite among broadcasters.

The 22D includes a four channel parallel mixing circuit
designed to work with 30 ohm dynamic microphones or
other sources of comparable impedance. Master gain control,
indirectly illuminated volume indicator, binding posts for
two program lines, jacks for two monitoring headsets, and
both binding posts and a jack for an order wire telephone
set are provided. There is ready accessibility to the interior
without disconnecting any cords or wires by simply re-
moving the rear cover.

Ouisionding Features

Real portable equipment; compact and light in weight.

Divided into two packages, each approximately 30
pounds, for balanced carryingr

Highly efficient performance.

Operates from an impedance of 30 ohms and into 150
or 600 ohms. A maximum gain of approximately 92 db
when operated between these impedances.

Frequency response uniform within :1 db from 30 to
I0,000 cycles.

Stabilized feedback.

Low harmonic distortion. Low noise level.

Operates from either a-c or battery power supply. The ac
unit has switch for instant change to battery supply in case
of a-c power interruptionr

Flexible control - four paralleled mixers and a master
gain control.

Contacts on output line keys, in unoperated positions,
Shortvcircuit inputs of outgoing lines. enabling station

167 7

Page 2

Wemm Electric Company

No.22-D SPEECH INPUT EQUIPMENT

Figure 20 7 Amplifier-control and Power Supply Units. Each case is
divided into two comparlmems, providing space lor arcessorles. The
lower compartment! 0! the Power Supply Carrying Case holds the bal-
Ieries when ballery nperalion is desired. The upper tomporlmen! holds
the me power supply.

Figure 21 - to": High! end 0! 1he Amplifier-conned Unil showing line
lerminulx, telephone binding posls and plug, plug lor moniloring head
so! and Ihe mul'i-pronged socket tar lhe power supply plug. Right: La"
end 0' lhe Amplifier-control Unil showing (our plugrin type microphone
receptacles.

operator to test the loops from master control.

Instantaneous interchange of program and order wire
lines in emergencies.

Indirectly illuminated volume indicator gives output level
in vu. Battery condition may be checked on volume indicator
meter during operation.

Range switth for adjusting normal level indication of
the volume indicator meter to correspond to output levels of
+4, +6, +8, +10, +12, or +14 vu (0 level calibration
1 milliwatt)

Nonrglare Alumilite finish on control panel.

Mushroom type mixer knobs with skirts and raised point-
ers facilitate fingertip control and avoid cramped hands.

Accessibility # ready access to interior without discon«
necting any cords or wires, simply by removing rear cover.

Microphone receptacle mounting plate removable and
readily adapted to substitution of other microphone re-
ceptacles.

Provision for two monitoring headsets.

Rugged construction assures long service and depend-

ability.

168

Specifications

Frequency Retpmzse: Uniform within i1 db from 30 to
10,000 cycles.

Signal-to-Noise Ratio: 66 db for battery operation and
60 db for ac operation; at 7.! db gain and referred to peak
output signal of +18 dbm.

Source Impedauze: 30 ohms, (Use 172A Repeating (Ioil
in cord [or ziorohm microphones).

Load Impedance: 150 or 600 ohms.
Gain: Maximum 92 db. Typical operating 70 db.

Mixer Controls: 45 db in 20 steps. 12 steps of 11/: db each
increasing on the last eight steps to cutofi.

Master Volume Control: Seventeen 2 db Steps. last three
steps have increasing attenuation to cut-off.

Maximum Outpul Level: + 20 dbm single frequency fundaA
mental with less than 1 per Cent harmonic distortion. +10
\u program level with 10 db peak factor.

Power Supply: A-C operation 71107120 volts, 50-60
cycles. Power consumption is 28 watts at 115 volts. Battery
operation - Filament 1,6 amperes at 6 volts and plate 21
ma. at 180 volts. Batteries not supplied with the equipment.

Varuum Tubes:

Qnmri/ l
RH/lill n/

Cumwerrial
Rereir'er Tl/zri

Amplmrr: 2 6]?
l are

rm ('1' Unit 1 so
4

Dimensions and Weights: Total weight of two units and
full equipment 50-60 pounds.

Component: Dir/lentil); ll"eig/7I
AmplifierACnntrnl Unit ll"\1$v$" 15 lbs.
Buttery Ruck Ass'y (Equ) . 3' 3' lllhs
AI. Power t'mr ~ "xs" 91/211»
Carrying Cases (2 Required) 15 x1633 5%" 12 lbs. ea.

Accessories: 633 or 639 type Microphones, and [he 1002F
Headset for monitoring purposes, are recommended.

l
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"w; . l

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Figure 22 7 Block schematic of MD Speech lnpul Equipment.