Transceiver Characteristics; Receiver Characteristics; Table 1-1. Adjacent Frequency Rejection - Hitachi ATT-20 Installation, Operation, Troubleshooting

1.3.2. Transceiver Characteristics

The ATT-20 may be operated from a constant potential
rectifier (CPR) supply, batteries floating on a CPR, or an
electronically regulated supply. Regardless of the supply
used, a surge ripple filter (STS USA N451590-0301) must be
used between the supply and the ATT-20 Transceiver.
Shunt Mode Output Voltage:
Series Mode Output Voltage:
Available Operating Frequencies: 12.28 KHz, 15.0 KHz, 20 KHz.
Carrier Frequency Tolerance:
Modulation Frequency (All Units): 390 Hz + 0.5%
Harmonic Output:
mode

1.3.3. Receiver Characteristics

Sensitivity:
Input Impedance:
Output Voltage:
ATT-20 Frequency
(KHZ)
12.28
15.0
20.0
Copyright 2019
CAUTION
-30 dB at second harmonic with 12 ohm load in shunt
7 ohm shunt mode; 1 ohm series mode
70 mVrms (modulated signal) + 14
7 ohms shunt mode, 1 ohm series mode
7.65 VDC into 400 ohms
Table 1-1. Adjacent Frequency Rejection
Adjacent Frequency of
Concern (KHz)
15.0
12.28
18.0*
20.0
15.0
18.0*
* Of concern where joint detectors are used.
SM 6299 Rev. 3, March 2019
ATT-20 Audio Track Transceiver
1.0 Vrms (modulated) into a 5-ohm load
0.25 Vrms (modulated) into a 1-ohm load
+ 0.5 %
mV
Rejection of Adjacent
Frequency (dB)
-18.0
-30.0
-21.0
-27.0
-44.0
-23.0
1-2