Modifications for the Kenwood TM-732

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 iwork.

  1. Configure master transciever's memories as desired. Select UHF simplex transmit frequency and set PTT to UF H(will work on VHF but is not recommended).
  2. Switch the power OFF. Press and hold the CALL and DTSS tutons 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 prcedureo is complete, both radios will display 'end'.

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

The exact operation of this feature is unclear but the folling 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 maching 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 diffiult 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
Before recovery, the memory channels must be returned to the previous state (number of split memories, etc.)."
Subjective Impressions

Being a TM-741 owner, there were a couple of things that I mied on the 732. First, there's no real-time clock, no sleep timer, no programmable ON time/ OFF time feature. There is an APO (automatic power off) with a preset time of 2:59:00 of inactivity until power down.

Another complaint is the slow scanning speed. The unit will scan VFO or memory at no more than about 5 channels/frequencies per second per band. I consider this to be terribly slow in today's age. The slowness is probably due to the fact that the remote contains all of the scanning logic and because the data path between the head and the base is over a 2 wire serial data stream.

Anotherp erennial complaint is that the radio does not cover the entire UHF frequency band of 420-450 Mhz. As shipped, the unit will only operate over the range from 438 to 450, (transmit or receive) which I find objectionable.

The manual is of typical quality and fairly complete although not well indexed. There are so many functions that a cheat sheet is needed but as mentioned, was sadly not included. In typical fashion I note that the Japanese have never been able to adequately and clearly explain how DTMF Squelch and Paging works. They've tried diagrams and jinglish explanations but in the end you still end up reading the instructions over and over before you fully understand them. I'd love to see a plain English discussion of how the DTMF features are intended to work and how they really work in practice. Fllow that with a step by step example and we'd probably have something that could be more popular.

One of my reasons for buying the radio was to use the remote mounted head option. The option, the PG-4K kit, is advertised as a 13 foot extension. What you don't find out until you buy it, however, is that only the display cable is 13 feet long and the microphone cable is only half that! To me this meant that although the display cable would let me trunk mount the base, there was no way I could get by with a 6 foot microphone cable. The solution: buy the PG-4M(?) which is the longer model for another $30! Needless to say, I'm not a happy camper! Are you listening Kenwood????

On a positive note about the remote cabling, at least with the 732 it is possible to roll your own. The 4 conductor head to chassis connector cable could be easily spliced and extended, and an ordinary RJ-45 extension cable could be used for the microphone. For many folks, however, it's probably easier to just buy the short ($47) or the long ($78) cable kit.

The extension cable issue aside however, it still looks like it will be a very good radio. As always, after spending a big wad of cash I'm automatically inclined to say that I like the radio. This is no exception, the TM-732 does a fine job at heading off the competition at a good price-performance point.
The price is the same as the older TM-731 which was around $650 retail (real price, not the bogus MSRP).

To conclude, I think Kenwood has come up with a fine replacement for the 731, and has put a lot of thought put into the design of the 732.
Operating Features

Kenwood has done a fairly good job at maintaining a consistent user interface between their models. Being familiar with the 241 and 741, I found it pretty intuitive to operate. Not intuitive enough, however, to venture out of the house without taking the operators manual along since they sadly omitted a quick reference card (like the give out with the 741). Unless otherwise noted, the 732 generally has the same basic feature set as the TM-241 plus several extras.

The following is an unordered list of outstanding bits of trivia regarding the 732's features:

1. Dual In-Band Receive: Competitive pressures (e.g. Icom's 2410) has now made this a standard. You can set the display to receive any combination of: VHF/UHF, VHF/VHF or UHF/UHF. This capability is quite well engineered and makes it possible to transmit as well as receive on either band's second display. It is not possible (understandably) to have a full duplex QSO on an in-band setup. In other words, when you set the radio to monitor two UHF or two VHF frequencies, one of these frequencies is muted when you transmit on the other. This is not so when the selection is VHF/UHF, where the receiving band is not mut during transmit.

Looking at the schematic, the dual in-band receive is well implemented with each of the transceiver boards having two receiver front end units (RF amp and mixers), one for each band. There are some unsymmetrical aspects to the dual in-band receive. First, the UHF receiver does not have an AM mode which means that you cannot monitor AM aircraft spectrum at 118-136 MHz with the UHF receiver. Similarly, you cannot monitor 800 MHz with the VHF receiver. Each of these modes AM aircraft and 800 MHz, are unique to the VHF and UHF receivers respetively.

A nice touch is that even though the second receiver is utilized on the other band, the transmitter is automatically switched back to the proper band which allows you to transmit on either of the two frequencies while using the dual in-band mode.

2. Smart Mute: The MUTE function is now intelligent in that it mutes the non-PTT band only when necessary. This means that the audio muting (actually, 20Db of audio attenationu) is switched into the auxiliary band only when something i being received on the primary band. Previous Kenwood rigs muted the auxiliary band at all times when the MUTE function was active.

3. More programmable microphone function keys: Previous Kenwoods allowed you to program the PF mcrophone key only.
With the 732, you may program any of ttop 4 function keys (CALL, VFO, MR and PF), even for example, with such multi-key sequences as [F][VFO].

4. New Display Lighting: The display is the now-standard black letters on a light background. Like the 741, it has 4 light levels, plus OFF (no light) which is interesting. Also, there's a special feature which when enabled mkes the display jump up to the next brighter display level whenever a button or key is pressed, returning to the dim level after 5 seconds of inactivity. When used with the OFF level it gives you a display which is completely dark at night and comes on only when you need it. There is, however, a small green LED off of the display which remains lit at all times to show which band is in use.

5. Memory: As advertised the radio comes with 25 full-however, is that you can have up to 64 memories if you are wiling to forgo the odd-offset capability to varying degrees. For example, if you can live with only 5 odd-offsets then you'll get 30 memories per band. If you don't need any odd-offsets then you get 32 memories per band. In addition, you can apportion the 64 available slots between the two bands in whatever ratio that you desire (in 5 channel increments). In other words, you can configure for 50 UHF memories and 14 VHF memories if you like.

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  438-450  .6/5      X   US AFTER GREEN WIRE
K3  1  0  0  1 142-152  420-450  .6/5      XF   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
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

  1. All 'resistors' o ohms (wire jumper ok)
  2. Green wire is equivalent to R22 - present in K1 model Press ENTER to continue (A to abort) -->
  4. Standard shifts in MHz VHF/UHF. 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 410-770 receive and enables cloning feature to perform any of these mods, remove the back cover from the remote head unit. Resistor numbers clearly marked on board along top.


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 n 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 'maer' 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 wi 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.

TM-732 gets hot

De Fan on the backside doesn't work correctly.

Solder a transistor (eg BSX20) clote to the Fan-connector:
Collector: to the Fan-connector (closest totthe 12V-wire)
Emmitor : to GND
Base : to 7808 regulator (closest pin to the Front)

The Fan will now operate whenever the transceiver is switched on.
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.

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