Modifications for the Kenwood TM-2570
The TM-2500 series radios may be easily modified for use on MARS/CAP
frequencies from 141-150.995 MHz.
Locate the control unit (X54-1860-XX) on the bottom of the radio. This is
the same board that the TU-7, and or MU-1 are mounted on. Just to the
left of IC3 you will find a row of diodes. Cut diodes D8, and D11. After
the diodes have been cut you will have to "reset" the microprocessor.
All of your programmed data such as memory channel data, DCL data, and
Phone number data will be erased and you will have to reprogram them. If
the radio is not reset, it will not recognize that you have cut the two
Press and hold the [PS] key.
Turn ON the power switch.
Release the [PS] key.
TM-2570 Low TX Power Output
Some owners of the TM-2570 have reportecd low transmitter power when the
radio is used with an antenna having reasonably low VSWR (1.5:1)
Remove the bottom cover on the heat sink.
Ensure that C72 is installed correctly. (Refer to Service Manual)
Squeeze the coils of L16 closer together.
Make sure that C72 and L14 are as far away from each other as
possible, move the capacitor, not the inductor.
Readjust VR1-VR4, according to the instructions provided in the
Service Manual. The protection circuit, VR4, should be adjusted for 8A at
146.000 Mhz rather than the values indicated in the Service manual. Change
your service manual to reflect this value.
Replace the bottom cover to complete the procedure.
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