TM231A

From    : N4YJC @ N4LDG.#MIAFL.FL.USA.NA
              OUT OF BAND MODIFCATIONS TO KENWOOD TM-231A
              CONDENSED FROM INFO BY:PAUL SAFFREN --- N6NHH
THIS MODIFICATION WILL ALLOW TRANSMIT THROUGHOUT THE 136 TO 173 MHZ
RANGE. FIRST OF ALL YOU SHOULD BE AWARE THAT THIS MODIFICATION DISABLES THE
AUTOMATIC ARRL TRANSMIT OFFSET FEATURE.
   YOU WILL NEED A 1N914, OR SIMILIAR GLASS DIODE (NOTE: IF YOU HAVE A CHIP
DIODE OF SIMILIAR RATING, ALL THE BETTER!).
   IT WOULD BE A GOOD IDEA TO WRITE DOWN THE MEMORIES ON A PIECE OF PAPER, AS
DOING THE MOD ERASES THE MEMORIES.
REMOVE THE 4 BLACK PHILLIPS HEAD SCREWS FROM THE TOP AND BOTTOM BLACK
METAL SHIELDS.REMOVE THE TWO METAL COVERS.
NOTE: IF YOU JUST WANT TO MOD THE RADIO FOR MARS/CAP, JUST REMOVE THE 
TOP COVER AND CLIP THE GREEN WIRE JUST ABOVE THE VFO,MR,MHZ SWITCHES,
AND REPLACE THE TOP COVER. THIS EXTENDS TRANSMIT ABOUT 3 MHZ ON EITHER
SIDE OF THE HAM BAND. 


LOOKING AT THE FRONT OF THE RADIO, YOU WILL SEE HOW THE BLACK FACE PLATE 
IS HELD IN PLACE BY 4 LITTLE PLASTIC KEEPERS. BY GENTLY INSERTING YOUR 
FINGER NAIL AND PUSHING EACH KEEPER, YOU WILL BE ABLE TO REMOVE THE FACE 
PLATE, PULL THE VOLUME, SQUELCH AND FREQUENCY SELECTOR KNOBS OFF. NEXT,
USING A PAIR OF PLIERS, REMOVE THE MIC CONNECTOR RING NUT FROM THE MIC 
CONNECTOR, NOW REMOVE THE NUT THAT IS ON THE FREQ. SELECTOR. REMOVE THE LCD 
ASSEMBLY FROM THE RADIO. THE NEXT STEP IS TO REMOVE THE METAL SHIELD THAT
COVERS THE CPU BOARD.  DO THIS BY REMOVING 4 SCREWS, TWO ARE LOCATED
ON THE SHORT SIDES AND THE OTHER TWO ARE LOCATED ON THE TOP AND BOTTOM OF
THE RADIO. GENTLY REMOVE THE METAL PLATE FROM THE RADIO AND PUT IT ASIDE.
FINALLY THE CPU BOARD MUST BE REMOVED. THERE ARE 3 SCREWS THAT HOLD THE CPU
BOARD ON TO THE RADIO FRAME. THERE ARE TWO MULTI PIN CONNECTORS LOCATED AT 
THE BOTTOM OF THE BACKSIDE OF THE CPU BOARD THAT CONNECT TO THE RF PORTION
OF THE RADIO.  REMOVE THE 3 SCREWS. GENTLY DISCONNECT AND REMOVE THE CPU 
BOARD.


    WHAT NEEDS TO BE DONE, IS TO SOLDER A DIODE TO THE PADS LOCATED UNDER
THE TONE SWITCH. (S205)  THIS IS D209 ON THE SCHEMATIC. YOU WILL PROBABLY 
NOTICE HOW SMALL AND HOW THINLY SPACED THE PADS ARE, AND YOU WILL BE WONDERING
HOW THAT BIG DIODE IS GOING TO  FIT!...
   2) MAKING THE MOD --YOU WILL HAVE TO FABRICATE YOUR OWN SMT DIODE. 
DO THIS BY BENDING THE LEADS OF THE DIODE UNDER THE BODY AND CLIPPING THE
REMAINING LEAD LENGTHS SO THAT SPACE BETWEEN THE LEADS ARE EQUAL TO THE 
SPACING OF PADS ON THE BOARD. THE DIODE MUST BE POSITIONED SO THAT THE 
CATHODE IS POINTING DOWN, TOWORD THE CPU CHIP.   THIS IS VERY IMPORTANT.
   3) RESET THE CPU. PRESS THE MR BUTTON AND TURN THE RADIO ON.
  THAT'S IT, JUST CONNECT POWER, ANTENNA AND THE MICROPHONE.  TURNING ON
THE POWER WILL RESET THE RADIO ERASING ALL MEMORIES.  OH WELL...
                        GOOD LUCK AND 73,
                       PAUL SAFFREN --- N6NHH
                       @KI6EH
----- END OF MESSAGE 23471 FROM WP4XQ @ WP4XQ.PR.USA.NA -----
                           IC-3200A FIX

sysop note:  Had to break this in two messages.  Original too long.
W2TKU@W2TKU-Sarasota,FL

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A QUICK AND DIRTY FIX FOR THE KNWD TM231A LOW MIC OUTPUT TILL (IF) KNWD
COMES  OUT WITH A FIX IS TO BYPASS R 63 (3.3K). R 63 AND R64 FORM A
VOLTAGE DIVIDER AT THE INPUT TO THE MIC AMP. R63 IS ON THE BOTTOM OF
THE RIG. WITH THE BOTTOM COVER OFF AND THE FRONT OF THE RIG FACING YOU,
LOCATE THE MIC AMP BOARD 3610    WHICH STANDS VERTICALLY OFF THE
MOTHER BOARD. FOLLOW THE 3RD PIN FROM THE LEFT  TO R63. A JUMPER HERE
GIVES THE TX AUDIO A NICE BOOST.  BE SURE TO READJUST THE DTMF OUTPUT
IN THE MIC (THE ONLY POT IN THE MIC).  73 AND GOOD LUCK. GREG.
 
         1951z, 473 msgs, #1786 last @KD6TH-4 MailBox>

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TM321A Mars/cap mod
from WM8J  msgID 2846_wa2rkn
 
To give the TM321 tx coverage from (142 0r 143, don't remember which) to
151.995 mhz, remove the top cover.  Look for a loop of wire comming from the
display area (the board with the CPU) and going right back.  Cutting this wire
and then doing a CPU reset is all you need to do.  Takes about 2 minutes.
Be sure that the ends of the wire don't short to something.
 
73s

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