Extended RX & TX Mods.
1200 & 9600 baud Packet Radio Mods.
Extended RX & TX.
Note this mod is for a Standard Kenwood TM732E (European) model type "E1". However if you have a USA version see the resistor matrix below for different configurations etc.
Remove power cables and coax etc. from radio.
By pressing the small release clip on the left of the display, remove the remote head from the main body of the radio.
Remove the access cover on the rear of the remote head unit.
Disconnect the white connector, leaving the remote head separate from the main body of the radio.
On the back of the remote head remove the two screws.
Now you should be able to see the PCB of the remote head.
If you look above the white connector "CN 1" you will see four "0" Ohm resistor positions, labelled R19,R20,R21 & R22.
You need to configure the resistors as in the photo below.
Photo shows radio after modification.
MODIFICATION MATRIX FOR THE KENWOOD TM-732
Model Resistors TX Ranges STD 22 21 20 19 VHF UHF SHIFT 800MHz 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 cut K3 1 0 0 1 142-152 420-450 .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 TX/RX 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 3. 0 = resistor present, 1 = resistor absent 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 410-470 RECEIVE and enables CLONING features
Switching between AM and FM (RX only)
To toggle between AM and FM, all you have to do is press and hold the "F" button, then at the same time press "MUTE". This will switch from FM to AM. Then to return to FM do the same, hold "F" and then press "MUTE".
This modification works 100% on my Kenwood TM732E. If you decide to carryout the same modification on your Kenwood TM732, then you do so at your own risk.
UHF 9600 baud packet radio mods. by G1IVG.
9600 baud TX mods (UHF)
1. Find the TX audio deviation potentiometer VR202 (47K).
2. You need to feed the TNC's 9600 baud TX audio, to a point between VR202 and resistor R257 (27K). This must be fed in series with a 0.1uf ceramic capacitor and a 56k ¼ watt resistor. Use screened cable and connect the screen to a nearby GND connection. On my radio I connected the TX Audio to the actual potentiometer, were it leads to R257.
9600 baud RX mods (UHF).
1. Find IC201 (FM IF module). Connect a screened wire from pin 12 (DET) to your TNC's 9600 baud RX audio input. Connect the screen to a near by GND connection.
1. Remove the front panel and gain access to the PCB of the control head. You need to connect a wire from the PTT line of your TNC to the PCB at back of the MIC connector. Pin 5 of the MIC connector is the PTT.
I have performed the UHF 9600 baud packet mods to my TM732 and it worked OK. I have been asked several times for a VHF mod.
"Untested" VHF 9600 baud packet mods.
(let me know if it works)
VHF TX Audio.
For 9600 baud on VHF feed the TX audio to the junction between R71 (22k) and R72 (120k) and Q21 (this can be seen at top left of the diagram).
VHF RX Audio.
Take the RX audio from Pin number 12 of IC1 (FM IF module). This is labelled "DET" on the diagram.
This is the same as for the UHF mods. Remove the front panel and gain access to the PCB of the control head. You need to connect a wire from the PTT line of your TNC to the PCB at back of the MIC connector. Pin 5 of the MIC connector is the PTT.
1200 baud Packet Connection.
For 1200 baud packet use, just connect your TNC to the MIC connector, for all TX and RX audio plus the PTT control.