Subject: Kenwood TM-741 Mods. PLEASE READ.
From: [email-masked] (Monte Freeman)
Date: 30 Sep 92 07:39:27 GMT
Newsgroups: rec.radio.amateur.misc

Hello,

  What follows is the collection of Kenwood TM-741/732 mods that I have
collected over time. I'd like to hear from anyone who has additions and/or
corrections to this list.

  Some time back someone posted a message asking if there would be any interest
in creating a kind of 'super-manual' for the 741. I replied to this person, but
never heard back from him. If I get enough interest; I may consider doing a
project like this myself.

  If you have any mods, tips, owner's manual corrections, or other information
that you think would be useful in a 'super-manual' like this, please let me
know or forward a copy of the information to me. Also, if you're interested in
helping out with creating the manual, please let me know.

  Here's my list of mods. Some of them I've made to my readio. Some I have
not. Please let me know what is missing or needs changing:

MODIFICATION MATRIX FOR TM-732A

    Resistors      TX Ranges       STD     Has
M  22 21 20 19    VHF      UHF    SHIFT    800     Remarks

K1  0  1  0  1  144-148  438-450  .6/5          Std. US Version
K2  1  1  0  1  144-148  438-470  .6/5      x   US After green wire cut
K3  1  0  0  1	142-152  420-470  .6/5      x   MARS/CAP Mod
K4  0  1  1  0	136-174  410-470  .6/5      x   All Band Mod
M1  0  0  0  0  144-148  430-440  .6/5          Generic Int'l Model
M2  0  1  0  0	136-174  410-470  .6/5      x   All Band Int'l (430 default)
E1  0  0  1  0	144-146  430-440  .6/(1.6)      Std Europe Model
E2  1  0  1  0	136-174  432-438  .6/1.6    x   Denmark
E3  0  0  1  1	144-146  410-470  .6/(1.6)  x
E4  1  1  0  0	144-146  430-440  .6/(1.6)  x
E5  1  0  1  1	136-174  410-470  .6/(1.6)  x   Europe All Band
C1  0  0  0  1	136-174  340-512  5.7/10        China Model

0 = Resistor IN     1 = Resistor OUT

Notes:

1. All "resistors" O ohms (wire jumper OK)
2. Green wire is equivalent to R22 - present in K1 model
3. 0 = resistor present, 1 = resistor absent
4. Standard shifts in MHz.  Those listed as (1.6) also do -7.6
5. Codes not listed are used in Japan version, special CPU required
6. M column is factory MODE number
7. K2 Mod includes 410-470 RECEIVE and enables CLONING features

To perform any of these mods, remove the back cover from the remote
head unit.  Resistor numbers clearly marked on board along top.

800 MHZ RECEIVE

To enable 800 receive, switch to UHF VFO (not available in UxU),
press and hold MHZ button until 800.000 appears.  

A capacitor must be added (C348) to enable the 800 receiver.  
To add, remove UHF transciever board and next to the pad of pin 1
of IC-202 (on the foil side), add a 2.2 pF chip capacitor. 
A wire can be used instead of the capacitor but sensitivity will
be reduced.  (See schematic diagram for reason).

HARD-WIRE CLONING  (Works in all confguration modes)

This procedure allows you to clone the entire memory of a "master"
transciever into the memory of a "slave" transciever.

First, construct an RJ-45 Jumper cable as follows:

------|                           |------
   UP ----------------------------- UP       Note that PTT and DOWN
    E ----------------------------- E         are crossed end-to-end
  PTT ----------------------------- DOWN
 DOWN ----------------------------- PTT
------|                           |------

For hacker's reference: UP=CLK, PTT=SO/, DOWN=SI

1. Configure the master transciever's memories as desired.

2. Switch power OFF, hold down F and MHZ keys and switch
   power back on while holding keys.  Display will show "CLonE".

3. Set the slave transciever in the clone mode (as in step 2).

4. Plug the cable into the two radios (which end does not matter).

5. Press the CALL button on the master.  When "End" is displayed,
   operation is complete.

ON AIR CLONING  (Does not work in K1 or E1 Mod modes)

This procedure allows you to clone a second transciever as above,
over the air.  The data is transmitted automatically using DTMF
tones.  During transmission (which is one-way only), the master
will automatically switch to LOW power.  To be legal, use only a
UHF cloning frequency.

This procedure is not enabled in the stock transciever.  At a
minimum, you must cut the green wire to make it work.

1. Configure master transciever's memories as desired.  Select
a UHF simplex transmit frequency and set PTT to UHF (will work on
VHF but is not recommended).

2. Switch the power OFF.  Press and hold the CALL and DTSS buttons
and turn the power back ON.  "CLonE" appears in display.

3. Set the receive frequency on the slave transciever the same
as that of the master.  Turn power OFF, hold down CALL and DTSS
keys and turn power ON.  "CLonE" appears in display.

4. Press the PTT on the master's microphone.  Data transmission
will begin.  In case of a receive error, the slave transciever will
display "Err".  When the procedure is complete, both radios will
display "End".

THE FOLLOWING FEATURES ARE UNVERIFIED, SO
YOU MAY NEED TO EXPERIMENT FOR YOURSELF

PAGING ANSWERBACK (Does not work in K1 or E1 Mod modes)

The exact operation of this feature is unclear but the following
description has been given:

1. To enable, hold down the F key and press the TONE key.

2. Do disable, repeat step 1

When enabled, documentation says: "If a matching code is received
and the other transciever is no longer BUSY, the code of the local
transciever is sent to the other transciever.  The answerback
function then turns off."

MEMORY RECOVERY (requires DTMF microphone)

(Documentation of this "feature" is difficult to comprehend but
perhaps someone will figure out what it does..  I suspect that
"RECOVERY" refers to returning the memories to their original
state after changing the split memory layout.)

1. Hold down F and C.SEL, turn on power

2. Press D, followed by 7 on the microphone. "Inspection Mode"
   is now enabled.

3. To cancel, press and hold F and then C.SEL

"Note: Before recovery, the memory channels must be returned to
the previous state (number of split memories, etc.)."

-------------------------------------------------------------------------------

           MODIFICATION COLLECTION FOR THE KENWOOD TM-741A TRI-BANDER
           ==========================================================

TM-741A/E FREQUENCY EXTENSION
=============================

Phase 1
-------

a) Slide the release knob on the front panel to the right
   and remove the panel (be careful with the cable between
   the panel and the main unit.)
b) Cut the green wire located in the left side (tape the
   bare ends of the wire to prevent shorts.)
c) Switch the power on (a melody sounds to confirm the
   change.)

Phase 2
-------

a) Unplug the connectors of the cable between the panel
   and the main unit.
b) Remove the two screws on the rear of the panel and open
   the rear of the case.
c) On the left side of the lithium battery there are four
   jumpers marked R54, R55, R56 and R57 corresponding
   respectively to b0, b1, b2 and b3 bits described below.

   Set the four bits as required for your country:

   - European Countries:
     mode $05

     b3 = 0
     b2 = 1
     b1 = 0
     b0 = 1

   - USA, Canada and Asia:
     mode $03

     b3 = 0
     b2 = 0
     b1 = 1
     b0 = 1

   WARNING: 0 => jumper set, 1 => no jumper.

d) Refit the rear of the case by reversing the order of
   disassembly.

Frequency range after modification
----------------------------------

|--------------------------------------------------------------|
|      ||  rx range ||  tx range ||           SHIFT            |
| unit || min | max || min | max ||   EUROPE    | USA CAN ASIA |
|------||------------------------||----------------------------|
|   28 ||  18 |  54 ||  26 |  45 || +/- 100 KHz |     iden     |
|   50 ||  40 |  90 ||  46 |  76 || +/-   1 MHz |     iden     |
|  144 || 118 | 174 || 136 | 174 || +/- 600 KHz |     iden     |
|  220 || 215 | 260 || 215 | 235 || +/- 1.6 MHz |     iden     |
|  430 || 410 | 470 || 410 | 470 || +/-1.6,-7.6 | +/-    5 MHz |
| 1200 ||1100 |1400 ||1100 |1400 || +35, -6 MHz | +/-12,-20MHz |
|--------------------------------------------------------------|

TM-741A/E AM RECEPTION WITH 28 AND 50 MHZ UNIT
==============================================

a) Press the [F] key, then press [BELL] key within
   ten seconds. An A is displayed at the hundred-MHz
   position to indicate AM mode.

b) To return to FM mode press the [F] again, then
   press the [BELL] within ten seconds.

TM-741A/E 900 MHz BAND RECEPTION WITH 430 MHZ UNIT
==================================================

Band change
-----------

To change to the 900-MHz band, select the 430-MHz
band, then press and hold down the [MHZ] key for at
least a second. Now 850.000 (initial setting) is
displayed.

To return to the 430-MHz band, press the [MHz] key
again for at least a second.

Adding a secondary 900-MHz dedicated antenna in the 430-MHZ unit
----------------------------------------------------------------

a) Remove the power supply cable from the power
   supply or battery.

b) Remove the 430-MHz band unit with care.
   For removal procedure see the INSTRUCTION MANUAL -
   UNIT INSTALLATION, reversing the order of the
   procedure and... using the brain!

c) Remove the shield plate (12 screws.)

d) Solder a coaxial cable (0.8 D) to the input
   side of IC9 (center is alligned with the IC9,
   ground at right side.)

e) Pass the cable throungh the notch and install
   the shield plate.

f) Reassemble the main unit.

TM-741A/E MEMORY CHANNEL DOUBLING
=================================

  Each band can be switched to the normal memory
(100 channels) and rear memory (100 channels). Each
band can contain 200 channels and... yes, a total of
600 channels can be used for three bands!

  SORRY! This function can be enabled only by extending
the receive frequency (see bulletin #1 of this
FREQUENCYEXTENSIONSNEVERENDHISTORY.)

  To switch the memory, hold down the [F] key and
press the [REV] key:

Normal Memory (100 ch) <--> Rear Memory (100 ch)

  The functions of the rear memory are the same as the
normal memory, but memory channels are displayed as
follows (rather than 01 to 00):

A1 - b0  ==  01 - 10        b1 - c0  ==  11 - 20
c1 - d0  ==  21 - 30        d1 - E0  ==  31 - 40
E1 - F0  ==  41 - 50        F1 - G0  ==  51 - 60
G1 - h0  ==  61 - 70        h1 - i0  ==  71 - 80
i1 - J0  ==  81 - 90        J1 - AA  ==  91 -100

TM-741A/E EXTENDED PAGING FUNCTIONS
===================================

Preliminary
-----------

Cut the frequency extension jumper as described in Phase 1
of the bulletin #1.

Answerback function
-------------------

Hidden function of the paging function.
If the answerback function is on, the code of the local
transceiver is automatically transmitted to the other
transceiver when the correct code is received to confirm
the code has been received.

OPERATION   After the correct code is received, if there is
            no BUSY signal, the code of the local transceiver is
            automatically transmitted to the other transceiver.

ON/OFF      To turn the answer-back on and off, hold down the
            [F] key and press then the [CALL] key.

Automatic release function
--------------------------

Hidden function of the paging function.

OPERATION   If the automatic release function is on, paging is
            terminated automatically when transmission ends after
            a call is received.

ON/OFF      To turn the function on and off, hold down the
            [F] key and press then the [SHIFT] key.

TM-741A/E DATE DISPLAY FORMAT
=============================

The normal date format is YEAR-MONTH-DAY. It can be
changed to YEAR-DAY-MONTH.

a) Remove the front panel and locate R60 and R61.

b) Move R61 (that is below R60) to the left.

c) Repack the front panel with care.

TM-741A/E DC POWER DISPLAY
==========================

Make the following change to display the SB line voltage
on the memory channel section when the time is displayed.

a) Remove the front panel and locate R60 and R61.

b) Move R60 (that is above R61) to the left.

c) Repack the front panel with care.

Since the voltage of the SB line to the panel is displayed,
it changes due to the loss caused by the wire and connector.

TM-741A/E HEADLIGHT LINKAGE DIMMER
==================================

Make the following change to reduce the dimmer level by one
step when the headlight is turned on (d4 remain unchanged).

a) Install DTC144EK on the panel printed circuit board
   (below R60 and R61).

b) Connect the load from the ILUMI pin of the panel
   printed circuit board to the 12 V side (where 12 V is
   output when the light is turned on) of the position
   light of the car.

TM-741A/E GAME MODE
===================

Simple games, such as a roulette game and a shooting game,
and music can be played using the frequency display.

To enter game mode, hold down the [F] key and the [MUTE]
key, and switch the power on.

1-2-3 is shown on the display. [BAND SEL A] selects Roulette,
[BAND SEL B] selects Shooting, and [BAND SEL C] selects Music.

To return to game selection mode, press the [VFO] key.

To exit game mode, press the microphone key or switch power off.

Roulette Game
-------------

* When the roulette game starts, the display shows [000],
  the transceiver enters the receive mode with the power on,
  and the three digits begin to run rapidly.

* When the [MUTE] key is pressed, [000] on the display can be
  changed: [BAND SEL A] stop the leftmost digit, [BAND SEL B]
  stops the middle digit, and [BAND SEL C] stops the rightmost
  digit. Other keys are not accepted.

* if the three digits match, the LED and illumination lamp flash
  and sound effects are produced.

* if [123] is displayed, a fanfare sounds. If the [MUTE] key is
  pressed, game mode is exited and the transceiver functions
  normally.

Shooting game
-------------

* When the shooting game starts, your score is shown in display
  section A, and cannon balls, target and remaining cannons
  are shown in display section C, strating from the left.

* If the [LOW] key is pressed, the game starts. The "number"
  attacks from the left of display  B. Take aim at the enemy
  "number" with the [TONE] key key, and shoot with the [MUTE]
  key. You win if 16 enemies are shot per screen. Thirty
  cannon balls can be used per screen. Each time you clear a
  screen, the speed increases. If eight screens are cleared,
  the first screen returns. The process is repeated.

Music
-----

When the music feature is selected, [ENJOY SOUND PLAY] is
displayed and the following tones can be produced:

  MR   = A           MUTE   = F
  MHz  = A#          CSEL A = F#
  CALL = B           BSEL A = G
  F    = C           CSEL B = G#
  BELL = C#          BSEL B = A
  TONE = D           CSEL C = A#
  REV  = D#          BSEL C = B
  DTSS = E

DISPLAY TEST

Hold down F and MHZ while turning on power.  This activates the display
test mode where all segments and indicators are lit.  Note the "ACC"
indicator at the lower right.  ACC is not defined in the manual, however
I saw it come on once one night after I started the car with the radio 
turned on.  The display lit up ACC and the UHF frequency display showed
some sort of HEX code (a ROM checksum maybe?).  

STRANGE TEST

(WARNING: YOU MAY LOSE SOME SAVED MEMORY DATA)

Hold down the F and MR keys while turning on power.  The radio plays
a wild sequence of tones and the displays go all crazy for several
seconds.  When it's done, everything seems normal except that the
memory contents are reshuffled and some memories are duplicated.
I can only speculate that this might be some sort of factory memory
test...

---------------------------------------------------------------------

UNDOCUMENTED TM-732A FEATURES

CLONE MODE

Hold down the F and MHZ keys while turning on power.  The current
control band will display CLonE.  Pressing CALL initiates the data
transfer, graphically illustrated by a moving S-METER display.  No
RF is transmitted during data transfer, instead it is assumed that
the data is dumped out of the microphone port.  Nothing more is
known about this at this time.

AM DETECTOR CONTROL

The AM Detctor, which automatically comes on below 136 MHz, can be
forced ON at any VHF frequency by pressing the F and MUTE keys
while applying power.  Radio continues to transmit FM but receives
AM.  Changing frequencies or memory channels will cancel the forced
AM mode.  This capability could be useful for listening to the
USAF Thunderbirds which sometimes operate in the 143 MHZ band using AM. 

  These are all of the mods that I currently have (I think). If anyone has
any corrections or additions to this list, please let me know.

  I'd like to put together as complete a list of the mods for the TM-741 as I
possibly can....

  Also, I've seen several references to the TM-732. Is this the same radio (as
far as being able to do mods) as the TM-741? I can't seem to find any kind of
a good description for the 732. Does anyone know of any mods for the 732 that
will NOT work for the 741?

   Thanks,

-- 
Monte Freeman  --  Operations Department / Information Technology
Georgia Institute of Technology, Atlanta Georgia, 30332
Internet: [email-masked]
Bitnet:   [email-masked]