PLEASE NOTE:! ============ ============ Most of the Modifications below work only with the old one: Kenwood changes the processors at ser-number 609001. From this time, the memory skip-function can be selected: during scanning the memories, some channels could be skipt. But: So far, the crossband-repeater could not be activated, yet. The old one don't! have this faeture, but the diode-matrix, as shown below, works correctly. *:Modification needed! CHANGING THE BANDS:* =================== Press the F-key and then press the LOW-button to toggle between Air-Band (340Mhz on the VHF Band) or the Phone-Band (850Mhz on the UHF band) and the amateur radio band. CROSBAND-REPEATER:* ================== The TH-79 does go into X-Band repeat. Press the "F" key then the "MONI" key to enter repeat mode. Use the same to return to normal. There is a 10 min transmit limit so it's not useable for long duration monitoring of a continuous transmission. That's understandable in light of the number of horror stories I've heard of people frying their HT's in repeat mode. CLONING THE TH79E* ================= To clone the memory contense of two radios on the air. The clone procedure is same with all others. ( use of DTMF tones, do not disturb transmission etc.) You must take care that both radios are really same: both have extended range or not, both are E-version or not etc. It will cause some problems if you try to clone i.e. an E version without expansion into a A- or J version. If you have both radios please hold down the -0- key / PAG L Key when you switch on the radio. So you see the letters CLONE on the display. Please push the ptt on the radio which has to be the master. It takes a time to transmit all memory with maybe names, call sign etc. After Clone is finished you see END written in Display. Best is to switch of both radios. After switching on again you will have two same radios ! EXTENDED RX/TX =============== Thats all...Don't cut the green wire, or install any jumpers as before. This mod is the official one from Kenwood, taken from a data sheet put out by them. 1. Open the unit by removing three screws from the back and one under the DC power input cover. Carefully separate the front and back pieces. The two case halves may be disconnected by pulling the wired plug and by prying the brown latch on the ribbon cable connector up enough to release it. 2. On the front PC board in the lower right corner as viewed from the rear with the knobs pointing up there are seven spots for diodes in a row, with one diode missing. | o o o o x o o | ________________| 2 3 4 5 6 7 8 The numbers are D302-D308, left to right, with D306 missing. 3. Remove diodes D304 and D307. Now you must have this: | o o x o x x o | ________________| 2 3 4 5 6 7 8 5. Reassemble and apply power. Mod complete. Now the ranges: 67-174.995 and 400-511.995 RX 136-174.995 and 400-511.995 TX. PS: Just cutting the green wire by the recharging jack is the MARS mod.. Don't cut if you intend to do the above mod.. Discription of the diodes: ========================== In my HT diode D303 are not installed, green wire cut. RX as wide as possible (69-179Mhz) and TX from about 130 to 179 MHZ. No crossband repeater. Now I tried to modify the handy, but i was not carefuly. I removed D305 and the Bander goes in the Lock-key modus: All keys are locked in cases of the Lock-switch. QRG disapeared and the channel nummbers shine on the display. Then I put D307 to the place I removed D305: Now I had the TH79A version with no light, but a call channel installed. All functions are the same as before, but TX was only possible on the amateur radio bands. Automatic shift keying as discriped in the manual for the american version. (Not to usefull in Europe :-), but you can change the QRG's now....) Not the situation on the TH79A I wand, I remount diode D306 to the location of diode D307 to change to TH79E back. And now the work was finished: Transmitting as descriped above, no lock function activ, crossband repeater enabled. THE MENU-SETTING 18 are activ: "Answer back function" for the paging mode: transmitts an code back to show that the call received. But the continues TRX showing up later in this doc has not been verifyed. The purpose of diode D302 was not to be able to find out because the first diode I wand to unmount had been damaged ;-( | o o x o x o o | ------------------ 2 3 4 5 6 7 8 Summary: (D1: not for the modification) D2: D3: D4: Extendex TX/RX (Removed=Enabled) D5: Key-Lock-Mode for commertial Use (Removed=Enabled) D6: Crossband-Repeater (Removed=Enabled) D7: Change A to E Version and back (Removed=A-Version) D8: Here is the MARS/CAP modification ================================= 1. Remove battery. 2. Open case by first removing 3 screws (#00 Phillips) on back and 1 screw on side hidden underneath the rubber flap covering the DC power jack. Gently pry apart starting at top; BNC connector will move with back, knobs with front. 3. Spread unit out. Wires will "hinge" on the side with the PTT button. 4. Looking on the back of the keypad (front) half, locate green wire on upper left, just below the CTCSS decoder module. 5. Neatly cut this green wire, and tuck back in so ends won't touch each other or other components. 6. Reassemble. Programmed memory will be lost since the CPU will notice the strap change and reset itself. Before: VHF RX - 118.000-173.995 TX - 144.000-147.995 UHF RX - 438.000-449.995 TX - 438.000-449.995 After: VHF RX - 118.000-173.995 TX - 142.000-151.995 UHF RX - 420.000-449.995 TX - 420.000-449.995 If I read the schematic right, the green wire corresponds to "W301", which also serves the same purpose as removing "D308". More research needs to be done on other mods; I'm especially interested in extending UHF receive beyond 450. There is a row of diodes right below the uC which appear to be D302 Remote Base Operation with Kenwood 732/733 ========================================== Kenwood has now simplified remote base operation of their mobile rigs with the TH79. This only works with the TH79A version. The Kenwood-Cooperation don't know this mod. I will not give a step by step on how to control the mobile rigs, since they are different. Hoewever, to really understand this feature, I would first get to know the remote control feature on the mobile very well. This makes the following explanation a little clearer! To access this feature, hold [PTT] and [MR] while [POWER ON]. The display will indicate -RC-, which I presume means 'Remote Control'. If you have correctly matched your DTSS codes, frequencies, etc, the dual bander's keypad now becomes a function pad. Pressing certain keys enables or disables functions on the mobile rig by sending the DTMF sequences for you. Please note that all this fuction does is send the DTMF tones over the air to control your mobile rig. I have not made a list of what each key does, but as the 79 sends the DTMF tones, the display will indicate the function. (i.e. - RPT ON, RPT OFF, TONE ON, TONE OFF, etc.) "The "RC" function is configured to directly control radios such as the TM-732. In fact, if you look at the layout of the microphone remote commands for the 732 it very closely matches the key assignments for of the "RC" mode. Since I have a TM-732 installed in my car, I had a chance to try this out and it's VERY convenient. Everything from direct frequency entry with the "F" key to enabling X-Band repeat. I'm really surprised they aren't marketing this feature of the radio." Measured specifictions of TH79 ============================== Band - VHF ----------------------------------------------------- Frequency Sens (uV) Power Mode --------- --------- ----- ---- 108 4 - A3 110 2 - " 115 .75 - " 120 .40 - " 125 .30 - " 130 .30 - " 135 .30 - " 140 .12 2.9 F3 145 .12 2.9 " 150 .13 2.8 " 155 .15 2.4 " 160 .18 1.9 " 165 .20 1.45 " 170 .21 1.10 " 175 .30 0.85 " 179.995 .35 0.70 " Band - VHF (2) (set to 300Mhz) -------------------------------- Frequency Sens (uV) Power Mode --------- --------- ----- ---- 300 50/75 - A3/F3 320 4/20 - " 340 .3/.6 - " 360 .2/.5 - " 380 .2/.6 - " 400 .2/.75 - " Band - UHF ----------------------------------------------------- Frequency Sens (uV) Power Mode --------- --------- ----- ---- 400 11 1.0 F3 410 4 1.5 " 420 1 1.85 " 430 .2 2.2 " 435 .12 2.3 " 440 .10 2.5 " 445 .10 2.5 " 450 .10 2.5 " 455 .15 2.3 " 460 .16 2.3 " 465 .20 2.0 " 470 .45 1.8 " 480 1 1.6 " 490 2 1.3 " 500 6 1.1 " 510 no RX over 509 0.8 " BTW, close inspection of the RF deck in my radio shows no obvious missing parts. I didn't remove the board to check the other side, but my suspicion is that the 800 MHz parts are installed. I'd be interested in input from others on that. So far I've not discovered how to make it display any 800 MHz frequencies though." CONTINOUS TRX ============= Pressing the VFO-key and the PTT key after a short beep and waiting a few seconds with these two keys pressed will bring the th-79e into continous transmit mode for about 10 minutes until TOT ends. This will also work with the MR key. Near the allodgment of TSU8 there is a green wire: cut it. 1 centimeter up there is a resistance of 0 ohm!!:remove it. So you can receive the 300 mhz band and the 900 mhz band (you can find now this function in the menu 20 and 21). To receive these frequences go in vfo mode and press F and then key "low/hi/lo/el";if you are in vhf vfo you receive from 300 to 399;if you are in uhf mode you receive from 800 to 999 You have the function of transponder too. To active this function go in dual mode(uhf-vhf)and press F and then the "moni" key. That's all for the moment,i hope you enjoy it. I'll send you other modifies if i'll receive something. From DG7RO: On my TH79 the continous trx doesn't work. I tried serveral ways but the hany goes not in the cont. trx mode at the end! For a 9600 baud packet radio modification, send mail to address below. thanks!