[ARC5] Photograph th the complete 1932 SCR-AA-183...First of 21 Sets In This Series

[Mike Morrow]

Photograph of the complete 1932 SCR-AA-183 (first of 21 different such sets) is attached.

SCR-AA-183   14 VDC   [Items with * are also part of SCR-AA-192, SCR-202]

Made by Aircraft Radio Corporation, Contract SC-132311, 06-25-1932

BC-AA-179*  Receiver
BC-AA-180   Transmitter
BC-AA-181*  Receiver Control Box
BC-AA-182   Transmitter Control Box
BD-AA-69*   Dynamotor Unit: 14 vdc IN, 235 vdc OUT
TM-AA-153*  Junction Box

Receiver Coil Sets:
C-97   224- 448 kHz
C-101 2500-4700 kHz
C-102 4150-7850 kHz

Transmitter Coil Sets:
C-115  6200-7700 kHz
C-119  3050-3800 kHz

RECEIVER:            Tuned Radio Frequency
Modes:               KEY (A2)/MIC (A3) (no mode switch)
Receiver Stages:     RF AMP1, RF AMP2, RF AMP3, RF AMP4    4x(VT-36 –> 36)
                     DETECTOR/AGC (diode connected)          (VT-37 –> 37)
                     AF AMPLIFIER                            (VT-38 –> 38)
Loop Connection:     None
AUTO/MANUAL Gain:    AGC is applied to first two RF amplifier stages.
                     MGC is applied to first three RF amplifier stages.
                     In AUTO, INCREASE OUTPUT changes receiver audio output
                     and transmitter side-tone level in headphones.
Screen Volt Divider: In dynamotor unit
AF Output Impedance: HIGH or LOW selected by internal wiring
AF Low Pass Filter:  In AF transformer primary

TRANSMITTER:         Master Oscillator-Power Amplifier
Modes:               REC(eive), (transmit) KEY (A2), (transmit) MIC (A3).
Power Output:        1.5 watts
Transmitter Stages:  MASTER OSCILLATOR                       (VT-25 –> 10)
                     POWER AMPLIFIER                         (VT-25 –> 10)
                     PA PLATE MODULATOR                      (VT-52 –> 45Spl)
                     TONE OSCILLATOR                         (VT-25 –> 10)

- The transmitter coil set consists of two physically separate coil assemblies:
    Master Oscillator – Plug-in, but requires removal of transmitter case
                        to change.
    Antenna           - Plug-in.  May be removed from the left side of the
                        assembled transmitter to adjust antenna load coil.
- Coils C-101 and C-119 are not normally supplied.
- The SCR-AA-183 is the earliest production military Model D set.
- This is the only receiver in the series that uses tube VT-36 in the RF
  amplifier stages.
- This is the only transmitter in the series that does not provide CW (A1)
  transmission.
- This is the only transmitter in the series that does not provide push-to-talk
  transfer from receive to transmit.  The REC-KEY-MIC switch on transmitter
  control box BC-AA-182 is used to switch between REC(eive) to (transmit) KEY to
  (transmit) MIC functions.  The key is part of control box BC-AA-182.
- There are no receive-transmit circuit or antenna switch relays in this system.
- Separate receive and transmit antennas are required.
- This set was intended to use keyed A2 MCW (KEY) rather than A3 voice (MIC) as
  the principal operating mode.  Thus, the transmitter mode/transmit-receive
  switch first selects KEY from the REC(eive) position, and then MIC.
- Dynamotor BD-AB-69 may be used in place of BD-AA-69.

Mike / KK5F
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