

In the TM-733 Service Manual, it describes a test mode that I haven't

seen mentioned anywhere else.  So, here's the scoop:



Entering Assembly Mode:  [CALL] + [MUTE] + [Power On]

All LCD segments should come on.  (To exit, power off.)



Press the [VFO] key.  *This must always be done first*

The serial port is checked and "F" with "80" on the display indicates

test passed.  "1" or "2" means failure.



Different keys now show different displays, with [LOW], [SHIFT],

[TONE], and [REV] also adjusting the backlight intensity.



Set the dials to minimum, then press the [MR] key.  Each of the dials

shows the digitized level.



This looks useful for checking all the keys and dials when you suspect

a bad connection.



Have fun!

-Steve







Out of curiosity, I've been trying to figure out how other variants of

the Kenwood TM-733A can be easily "mutated" from the American "K"

version.  If you're one of those folks that gets their panties all in

a bunch over the possibility of out-of-ham-band transmit, you can skip

this article.  I'm responsible for my own transmissions, as is anyone

else.



Here's what I've come up with so far.  I'm curious to know if anyone

else has tinkered with this stuff.  I figure since the radio is so

new, every one out there is still under warranty, so there probably

aren't many folks poking about with a soldering iron...



The K and P (Canadian) models seem physically identical so far.  Only

the warranty card has a different part number.  Is there anything else

I've missed?



The M2, M3, M4, and E2 models have the most liberal Tx frequency

ranges: 136-174 & 410-470 MHz, instead of the US ("K") version's:

144-148 & 438-450.



The K version already has the widest 2m/70cm Rx range possible:

118-174 & 410-470, so there won't be any mods there.



The K and P models are lacking significant hunks of the 800 MHz Rx

circuitry.  In addition to some caps and inductors to link in the 800

MHz font end, IC202 is completely missing (the chip with "80R"

output).  I think it's a custom chip, so there's not much chance of

finding one.  ALL models other than K and P have this chip.  If you're

really desperate to get the 800 MHz Forbidden Band, you'll have to buy

another radio, or try to order the chip from Kenwood Parts.



Also, K and P models have a "KCB20" for IC209 instead of KCB14.  This

is the "430 MHz Transmit Drive" chip.  I think K is optimized for ~445

while the other is centered at ~435, but I'm guessing.  The

test/calibration instructions use different test frequencies for the

two models, so there is probably some difference in the specs.



As for the CPU, it seems to detect which model it's in by reading pins

90 through 93 on power-up.  (These are output lines to the DTMF

encoder after power-up.)  The pins are selectively pulled hi/low by

wires and resistors to set the model.



If anyone knows how to override this setting by front-panel (software)

controls, I'd be very interested to hear it!



As for hardware configuration, here's the info:



There are two wires (W1, W2) installed on the CPU board that

apparently bypass resistors, tying the lines hi via 10k ohms (CP402

Rpack) instead of low via 100k resistors (CP403 Rpack).  There are

also three zero-ohm resistors that do something similar.



For those of you following along at home, that does indeed make five

select lines, with only four going into the DTMF chip. :) I'm not sure

about the fifth one, R413.  It goes lots of places, including several

dispersed pins on the CPU.  It's only installed on the M4 (Chinese)

model of the radio.  Since the M4 model also uses a Chinese

front-panel display, this line probably selects different glyphs and

such.  It's also tied into the descriptionless pin 77 of the CPU,

called "RPT" (cross-band repeat?).  Maybe they can't sell

cross-banders in China.



The other four: W1/R410, W2/R411, R412, and R414 are the selectors

that pull on the DTMF data lines.  If we ignore the M4 and E models

(which have more unique components), the K and M2/3 models have only

these differences:



        W1,2  R414

  K,P   Yes   Yes

  M2/3  No    No



I'd bet one of those accounts for the different Tx range limits on the

CPU.  Maybe the other allows for 800 MHz frequency tuning.



So, is anyone else working towards mods for this radio, however useless?



Happy Hacking!

-Steve











 Ne> There are two wires (W1, W2) installed on the CPU board that

 Ne> apparently bypass resistors, tying the lines hi via 10k ohms (CP402

 Ne> Rpack) instead of low via 100k resistors (CP403 Rpack).  There are

 Ne> also three zero-ohm resistors that do something similar.



 Ne> The other four: W1/R410, W2/R411, R412, and R414 are the selectors

 Ne> that pull on the DTMF data lines.  If we ignore the M4 and E models

 Ne> (which have more unique components), the K and M2/3 models have only

 Ne> these differences:



 Ne> W1,2  R414

 Ne> K,P   Yes   Yes

 Ne> M2/3  No    No



 Ne> I'd bet one of those accounts for the different Tx range limits on the

 Ne> CPU.  Maybe the other allows for 800 MHz frequency tuning.



 Ne> So, is anyone else working towards mods for this radio, however

 Ne> useless? 



I got a "Kenwood Supplementary Info" sheet from the dealer with my

733.  It describes removing a chip resistor "B0," also identified as

R414, followed by resetting the CPU by holding the MR key and turning

on power, then pressing MR again.



It says that will open transmit from 136-173.995 MHz and 410-469.974

MHz, and receive from 118-173.995 MHz and 300-469-975 MHz.  (I've seen

net bulletins that say it's not really receiving 300 MHz even if the

display is reading 300 MHz).



The sheet also shows "B1" (R-412), and two jumpers, B2 and B3 which

jumper solder pads right next to R-412 and R-414.  The instructions

don't make any mention of doing anything with those parts.



Thanks to Steve for his early hacking, and especially writing about

the 733.



73, Gary KN4AQ, Raleigh NC

KN4AQ.GARY@MMS.RALEIGH.NC.US






I just talked to Kenwood and found out a few new things about the

TM-733A.  I haven't tried most of these yet (because my radio is all

taken apart), but I'll pass the info along.



////

The extended range modification:

  They *do* have an official extended range modification, but they will

  not send it to you unless you first send them proof of MARS or CAP

  enrollment.  I tried to explain to them that I want to transmit into

  the hamsats at 435 MHz, but they didn't care.



////

The official word on the dirty CTCSS tones is that it's still an

unknown problem, and there is no Service Bulletin to correct it.  If

enough people notices the grunge in the outgoing tone and call them

about it, maybe they will check into it.



////

The partially-documented "External Remote Control Operation" is

documented in App Note AAN-0006.  Some people have found that when

remote control is enabled, the microphone is hot and will hear DTMF

tones coming from the speaker if the volume is turned up and the mic

is near.



To remote-control the radio with the microphone disconnected (yeah!),

they offer this procedure:

- Pick a UHF control frequency.

- Turn on the UHF DTSS function and select a tone sequence.

- Turn the UHF DTSS function back off.

- Press Band Select to move to the VHF band.

- Turn OFF the radio, press and hold the [CONT SEL] key, turn on the

  radio, and then release the cont key.  This will place you in the

  EXT standby mode.  The S-meter scale and the DT indicators for the UHF

  band will begin flashing ON and OFF.  The LOCK indicator will turn ON,

  and most front-panel keys (PWR stays) will be disabled.

- To begin remote control, you should key the external radio and

  press the following key sequence: "Axxx#" where "xxx" is the preset

  DTSS code selected earlier.

- If the proper code is received by the 733, the beeper will sound and

  the "DT" indicator will stop flashing.  The radio can now be

  remote-controlled, using the function chart in the manual (p. 81?).

- The return to standby mode, press "A#" on the remote radio. 

- To return the radio to normal operation, turn the radio off, then

  press and hold [CONT SEL] while turning the radio back on.  Repeat

  one more time. (really!)



Wow!  I would have never figured this out on my own.  I was beginning

to think that the acoustic-coupled mic/speaker was the only way to

remote control it.



My reading of the instructions is that it starts off the remote

control mode "locked", which is a good idea.  You can then unlock and

relock it with the DTMF code sequence.  Pretty cool.



////

The advertised but undocumented Wireless Clone function is described

in App Note AAN-0008 which they will mail out on request.  (Maybe if

enough people ask for it, they will include all the functions in

future instruction manuals.)  In summary: 

- Prepare the two radios for simplex operation on the same frequency.

- Turn both radios off

- Press [CALL]+[SHIFT] + [Pwr On].

- This should place the radios is clone mode with "CLonE" on the display.

- Press PTT on the "Master" radio momentarily.  This will start

  sending the programming DTMF tones.

- After all data has been transferred, the display of all radios will

  read "End", indicating success.

- If the signal is interrupted or corrupted, the "Slave" displays will

  read "Err".  Turn them off and try again.

Notes: 

- Both the Master and Slave radios must have the same number of

  memory channels available for each band.  Example: You can not clone a

  stock Master to a Slave with ME-1 memory expantion.

- You can not clone between different Kenwood radio models, even if

  they seem identical.



////

The advertised but undocumented cross-band repeat function is

described in App Note ANN-0009.  Most people have already figured this

one out.  



Basically, you set up the VHF and UHF bands, then select the "X" icon

from the [F](for 1 second) menu.  For bi-directional repeater

operation, make sure the PTT and Control bands are different, usually

by pressing Cont Sel once.  If the PTT and Control indicator are on

the same side, then it will only retransmit the other band to that

side (for one-way extender operation).  All the decimal points will

light up when in repeater mode.  The remote control sequence to turn

on/off repeater mode is "DC".



The transmitter hang time can be toggled between 500ms to 0ms by

turning on the radio with [LOW] pressed.  They also recommend enabling

the Time-out Timer, for obvious reasons.



////

The "Assembly Mode" for testing the control panel indicators, buttons,

and knobs is documented only in the Service Manual.  I posted a

summary a few days ago.



////

So, there you have it!  When I get the mods all figured out and

tested, I'll try to post a full report with details on all the

undocumented features and the mods.  This should end up in the

archives somewhere.



Happy Hacking!

-Steve



Steve Haehnichen                 Vigra, Inc.  San Diego, CA

steve@vigra.com                  (619) 597-7080 x116   Fax: (619) 597-7094

