Service manual

GENERAL INFORMATION
1-5
November 2001
Part No. 001-7240-001
7243 SPECIFICATIONS
The following are general specifications intended for use in testing and servicing the transceiver. For current
advertised specifications, refer to the 7243 product information sheet available from your E.F. Johnson sales repre-
sentative. Specifications are subject to change without notice.
GENERAL
Operating Mode LTR-Net/LTR (trunked), and conventional (non-trunked)
Frequency Range 430-470 MHz
Systems Programmable Up to 16-100 depending on system type and number of groups
Groups Programmable Up to 99 per system
Transmit/Receive Separation Within channel spread, 0 MHz conventional talk-around
Channel Spacing 12.5 kHz - 2.5 kHz maximum deviation
25 kHz - 5 kHz maximum deviation
Frequency Stability (tx and rx) 2.0 PPM –22° to +140° F (–30° to +60° C)
Dimensions (with battery and controls) 5.7" H x 2.2" W x 1.4" D
145mm H x 55mm W x 35mm D
Weight (with battery) 15 oz. (410 g)
Power Source 7.5 VDC nickel metal-hydride (NiMH) battery pack, 1450 mAH
Typical Battery Life (5-5-90) 7.3 hours (high power), 9.9 hours (low power)
Compliance FCC parts 15 and 90
Circuit Protection 3-ampere fuse
RECEIVER
Sensitivity 0.35 µV (12 dB SINAD)
Selectivity –65 dB at 25 kHz /–60 dB at 12.5 kHz
Spurious and Image Rejection –65 dB
Intermodulation –65 dB
Audio Output Power Internal Speaker - 0.5 watt (16-ohm load)
External - 1.5 V rms (680-ohm load)
Audio Distortion Less than 5% at rated power (0.5 watt)
Audio Response +1, –3 dB at 6 dB per octave de-emphasis characteristic
Channel Spread 40 MHz
Current Drain Standby (squelched) - 100 mA maximum
Rated Audio Output - 275 mA maximum
TRANSMITTER
High RF Power Output 4.0 watts
Low RF Power Output 1.0 watt
Spurious and Harmonic –60 dB
FM Hum and Noise –40 dB at 25 kHz, –34dB at 12.5 kHz
Audio Distortion 5% maximum at 1 kHz
Audio Frequency Response +1, –3 dB from a 6 dB per octave pre-emphasis characteristic
Audio Modulation 11K0F3E, 16K0F3E
Channel Spread 40 MHz
Current Drain (maximum) Low Power - 950 mA
High Power - 2 A
Load Impedance 50 ohms
Duty Cycle (3-3-54 seconds) 5% (Transmit-Receive-Standby)