Modifications for the Kenwood
TM-241
19-07-1998 TM-241A RX/TX
mods
This mod is only intended for experimental applications
only! Know what freq you are on and don't use this mod if you are not for
sure.
The TM-421a is capable of transmitting from 136 to 174 MHz when the
following modification is performed. The transmitter specifications will vary
from published in-band specifications.
- Remove the top and bottom covers from the transciever.
- Remove the knobs from the front panel.
- Remove the nut from the mic jack and the nut from the channel selector
switch.
- Remove the 4 screws that secure the front panel to the body of the
transceiver.
- Pull the front panel off the transceiver to expose the Control board.
- Remove the 3 screws from the Control board. Gently pull the board off the
transceiver.
- Cut the GREEN jumper wire on the Control board.
- Install an MA141A chip diode or 1N914 diode as D209 on the Control Board.
- Reassemble the transceiver by reversing steps 1 - 6.
- Reset the microprocessor by holding in the MR key as power is turned on.
+-------------------------------------------------------------------------+
¦ D209 ¦
¦ +-+ +-----+ ¦
¦ ¦Ú¦- ¦--¦Ú+---+ ¦
¦ ¦ ¦ ¦
¦ ¦ ¦ ¦
¦ ¦ ¦ ¦ ¦ ¦
¦ ¦ ¦ +-+ ¦
¦ +-----------------------+ +-------------------------+ ¦
¦ ¦ [] [] [] [] [] [] [] ¦ --+ ¦ [] [] [] [] [] [] [] [] ¦ ¦
¦ +-----------------------+ ---+ +-------------------------+ ¦
¦ ¦
¦ ¦
+-------------------------------------------------------------------------+