TM 32-5835-001-24 & P
drive for the take-up reel while the capstans control the speed of the tape past the
heads. In conjunction with moving the slide plate to provide the selected tape speed,
the mode selector knob also actuates switch 3A4S1 to provide voltage of the proper
polarity to drive the reel motor in the correct direction. When F/F, REC, or REPRO
modes are selected, the motor rotates in a direction to move the tape in a forward
(from supply to take-up reel) direction. When F/R (fast reverse or rewind) is
selected, the tape moves from the take-up to the supply reel.
(7) Record /reproduce electronics. The recorder set utilized a common signal
amplifier for the record and playback (reproduce) processes. For two channel oper-
ation there are two identical circuits. Only the bias oscillator is common for the
channels. In the following discussion the operation of channel 1 will be explained in
detail. When the mode selector is in the REC position, signals from the microphone
jack 3A3J2 and the radio receiver jack 3A3J1 are combined and connected to a sum-
ming point on the motor-bias card for mixing with the bias signal. The bias oscillator
is turned on to provide the high frequency bias required for recording with low dis-
tortion, and the combined data and bias signals are applied to the record head direct-
ly . The other lead of the record head is grounded through 3A4S4 (channel selector)
with the receiver jack to permit listening to the receiver signals, whether or not the
recorder is operating. The function of the channel selector is as follows:
Channel
Headphone 2
Selector
Headphone 1
Position
1
Channel 1
1-2
Channel 1
Channel 2
2
Channel 2
The headphone ground is connected to the receiver ground at terminal 3A4E3. When
the REPRO function is selected, the microphone and radio receiver inputs are discon-
nected from the amplifier and the audio (record /reproduce) head is connected to the
amplifier input. The bias oscillator is turned off and the audio head functions as a
reproduce head. The headset is switched to the amplifier output to permit monitoring
of the previously recorded data. The following are nominal input /output character-
istics of the signal electronics; receiver, 0.5 to 5 mVrms; microphone input, 0.1 to
1 mVrms; and headphone output, 0.0 to 20 milliwatts.
(8) Control logic circuits. Control logic in the recorder consists of the
mechanical positioning of the mode selector and the applicable portions of the mechan-
ically coupled switch 3A3S1, and the automatic end-of-tape sensor circuit. In addi-
tion, the end-of-tape sensor circuit contains an Elapsed Time Indicator and a Tone
Generator which alerts the operator that end of tape has been reached.
b. Power Supply. As shown on the schematic diagram (figure FO-1), the power
supply will operate with any one of four inputs (+12 Vdc, +28 Vdc, 117 Vac, or 230
Vat) to provide the output power required for the recorder.
3-2. Functional Circuits. Operating principles of
each functional circuit of
the re-
corder set are located with its functional schematic on foldout pages at the end of
this manual.
3-5