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Sleep Mode 1 in the M7 Data Radio

In the M7 radio, Sleep Mode 1 is enabled with the ATSM 1command.  There also must be 3 components installed on the circuit board of the M7 radio to allow sleep mode 1 to work. It is highly recommended that this modification be done at Raveon, or by very qualified technician skilled in fine-pitch soldering.  Damage to the M7 due to the installation of this modification by a customer is not covered under warranty. 

When the three components are installed, the DTR line on the RS232 serial port may be used to turn the M7 data radio on and off.  The three components are R43, C21, and R12.  R43 should be a 1K 0603 resistor.  R12 should be a 10K 0603 resistor, and C21 should be a 680pF 0603 ceramic capacitor, 50V rated.

I/O Circuit

M7 I/O Circuit Schematic

To access the three components, the main circuit board in the M7 must be carefully removed.  Remove the 4 screws securing the front pannel, the two screws on the side and the four screws that hold the back panel on.  Then removed the one screw on the bottom of the unit that secures the voltage regulator.  Slide the PCA out of the enclosure.   

The location of the three components on the printed circuit board is shown below:

Once these components are installed, the DTR input will control the power supply of the M7 radio. If DTR input is below about 0.8V, the M7 radio will power off.  If DTR goes above about 3 V, the radio will power on.  In Sleep Mode 1, and external device must control the DTR line.  The radio cannot turn itself on or off.  If nothing is connected to the RS 232 serial port, the radio will be turned off, because R12 is a pull-down resistor, and will cause the radio to turn off if no signal drives the DTR line.

Once the modification is complete, re-assemble the M7 in hte reverse order is was disassembled.

Filed under: Hardware Information, Transponder Installation | Posted on November 29th, 2010 by John Sonnenberg

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