Title: All about the TH79 (2.0) Hello TH79 fans. I tried to publish the optimal/maximum functions/reorganizations of the TH79 for the Europe area. Moreover there are many tips and tricks on this handheld transciever. Perhaps you can use this dokument like a FAQ already ... Remark: The modifications have done on the TH79E with the serial number 90200050. Models with the serial number 60300100 (memory skipping function F+L. OUT doesn't work) canīt maybe use the crossband- repeaterfunktion. But there maybe exists a modification for recieving down to 67 MHz. Who knows more? Does this work with new models, too ? 1.0 RX/TX expansion TH79 TX/RX-Qrgs after the modification: In the upper receiver/transmitter (better use for 2 m) RX: 118-135 MHz (VHF) AM 136-173 MHz (VHF) FM 300-399 MHz (VHF) AM/FM 410-469 MHz (UHF) FM TX: 136-173 MHz (VHF) FM 410-469 MHz (UHF) FM In the lower receiver/transmitter: (better use for 70 cm) RX: 118-173 MHz (VHF) FM 410-469 MHz (UHF) FM 800-999 MHz (UHF) FM TX: 136-173 MHz (VHF) FM 410-469 MHz (UHF) FM After the modification the TH79 have to be programed again. To use the areas of 300-399 MHz and 800-999 MHz you have to push + (transmit power button) in the VFO mode at the corresponding reciever. After that you can store the frequencies. 1.1 preparation a . remove microphone, accumulator, antenna b . remove the screw at the direct current socket and the little screws on the back with a fitting screw driver. c . open the TH79 and put the front of the transmitter on the display. 1.2 modification a.remove the green wire near to the CTCSS socket. b.on the main board there are down on the right corner a row of a SMD resistance and 7 SMD diodes with missing 1 diode already. The diodes are labeled with an "A". c. Now you have to remove the third diode (D306) from the right end counted Hereīs a little graphic: Before: R D D D D D D | R=resistance ________________| D=diode 1 2 3 4 5 6 7 8 =nothing Afterward: R D D D D D | ________________| 1 2 3 4 5 6 7 8 d. put together again and program again the TH79 : -) 2.0 additional functions of the TH79 after the modification of point 1 2.1 Crossbandrepeater It is only possible to cross frequencies from the UHF-RX to the VHF-TX or from the VHF-RX to the UHF-TX. Just view the RX/TX list of point 1. For activating the mode push +. Switching off again with . You should choose the right TX-power before. The TH79 stopps crossing, after 3 minutes sending all the time, not to damage the TH79. 2.2 Cloning a. Push PTT- and VFO-button during switching on. (You need only to do that at the first time Cloning) b. Choose TX-Qrg and TX-Power c. Turn off d. Push 0 during switching on. CLONE appears on the display. e. Take other TH79 in Cloning mode. f. Push PTT at the sending TH79 and wait about 4-5 minutes g. After successful Cloning both TH79 displays END. Recieving TH79 will display ERROR, if there has been any errors during transmission. 2.3 new menu items a. menu item 18 AnswerBack: ON/OFF With this menu item it is possible to switch on/off the automatic confirmation of a pagingcall in the Pagemodus. b. menu item 19 FM/AM Mode: FM/AM With this menu item you can toggle between AM- and FM- Mode in frequency area 300-399 MHz. You can see the decimal line (4*2 pixels) in AM-Mode and the decimal point (2*2 pixels) in FM-Mode on the display between chosen frequency. c. menu item 20 Prog VFO: 300-399 You can choose the VFO area between 300 and 399 MHz. d. menu item 21 Prog VFO: 800-999 You can choose the VFO area between 800 and 999 MHz. 3.0 text messages Recieving: The function DT(ss) or PAG(e) must be switch on to use this feature. On the display must PAG or DT appear. Transmitting: The message may not be longer than 6 signs and will be transfered by DTMF. Hereīs a conversion table: 0 = 0 Q = 1+A Z = 1+B = 1+C 1 = 1 A = 2+A B = 2+B C = 2+C 2 = 2 D = 3+A E = 3+B F = 3+C 3 = 3 G = 4+A H = 4+B I = 4+C 4 = 4 J = 5+A K = 5+B L = 5+C 5 = 5 M = 6+A N = 6+B O = 6+C 6 = 6 P = 7+A R = 7+B S = 7+C 7 = 7 T = 8+A U = 8+B V = 8+C 8 = 8 W = 9+A X = 9+B Y = 9+C 9 = 9 You have to send out the message like this: ## E.g.: DTSS or page number of the Reciever: 275 Message: "TEST" = 8A3B7C8A Petition: 275#8A3B7C8A# Of course the DTMF memory can be used for that, too. You can test that feature with only one TH79 ! You can use the third harmonic wave for that test. The Duplex- mode (F+DUP) must be activated. Try it ! E.g.: 1. Adjust 144.900 MHz on the upper TRX. 2. Use only low transmit power or dummyload 3. Adjust 434.700 MHz on the lower TRX. 4. Activate Duplexmode (F+DUP) 5. Activate DTSS on the lower reciever. 6. Choose DT-code 7. Reduce volume 8. During transmitting with the upper TRX you have to enter e.g.: 275#8A3B7C8A# 9. Now youīll be able to see the result on the display for the lower TRX. 4.0 sensitiveness TH79 Results only have to be regarded as guide values. Frequency [MHz] | performance [dBm] tension [uV] ------------------------------------------------ 118 AM | -110 0.71 120 AM | -115 0.4 125 AM | -125 0.12 130 AM | -127 0.1 136 FM | -122 0.18 140 " | -126 0.11 145 | -129 0.08 150 | -129 0.08 155 | -125 0.12 160 | -122 0.18 165 | -118 0.28 170 | -116 0.35 173 | -114 0.45 300 AM | -95 3.9 310 " | -109 0.8 320 | -124 0.14 330 | -128 0.09 340 | -131 0.06 350 | -135 0.04 360 | -135 0.04 370 | -136 0.04 380 | -136 0.04 390 | -136 0.04 399 | -135 0.04 410 FM | -109 0.8 415 " | -116 0.35 420 | -123 0.16 425 | -126 0.11 430 | -128 0.09 435 | -128 0.09 440 | -128 0.09 445 | -127 0.1 450 | -125 0.12 455 | -122 0.18 460 | -118 0.28 465 | -114 0.45 469 | -111 0.63 800 FM | -85 12.6 825 " | -90 7.1 850 | -95 3.9 875 | -100 2.2 900 | -105 1.25 925 | -110 0.71 950 | -110 0.71 975 | -110 0.71 999 | -110 0.71 5.0 Modification TH79 for 70cm 9K6/Pocsag RX! TX? : Well, a really difficult thing... There will be no problems with recieving 9k6 signals or 512, 1200 or 2400 baud Pocsag signals. There will be problems with TX. Who has a better idea to solve the problems than my following ??? Depending on DIGI you have more or less success with 9K6-TX. I have tested DB0ABH (about 15 km) and DB0ZB (about 80 km). DB0ABH has only got every 20th frame, but DB0ZB every 1,5th. Short Frames go quite speedy, but the longer ones are causing waiting for hours :-( The TH79 maybe tries to adjust the frequency during transmission :-( Are there any other ideas to solve that problem ??? Unfortunately, I couldn't test Pocsag TX yet. For RX-Broadcast, of course itīs a fine thing. 5.1 preparation a. Remove microphone, accumulator, antenna b. Remove the screw at the direct current socket and the little screws on the back with a fitting screw driver. c. Open TH79 and remove CTCSS cap d. Turn the front of TH79 on the display on the left side and the back on the right side e. For better working you have to remove the flat ribbon cable. Use a little screw driver for removing the cable out of its fastening. Now you can pull out the cable. 5.2 RX-modification a. You have to solder the connection of the antenna socket away. antenna socket. Push the wire a bit away during soldering. b. You can pull the black plastic away, after you have removed the sealing ring around the antenna socket. You should remove a bit of the foam material before. c. Remove 2 screws at the antenna socket. After that you can remove 5 screws of the sheet copper. (Perhaps 1 screw hides under the foam material or under the flat ribbon cable). Now you can remove the board from the back. d. Now we care about the back of the board. You can get the RX-signal from the IC MC3372D (16 pins) from Motorola (UHF-Demodulator). The RX-cable have to be connected with Pin 9 (above on the right of the IC). The cable can be carried out like this: *-------* ! ! *---------------------------* ! ! *---* ! ! ! ! ! ! ! ! ! *--* ! ! !IC! ! ! *--* cable run ! ! ############## ! ! ........<= solder # !run cables through here ! ! 3372 ! here #### ! ! PIAK ! *---* ! *------* ! ! *----------* ! ! ! IC ! ! ! *----------* ! ! ! *-----------------------------------* e. Put together again. Donīt forget the antenna socket... 5.3 TX-modification a. There is a doughter board put on the main board in the TH79. Itīs connected on the lower right side through a pin with the main board. You have to solder off the pin. b. The doughter board can be removed now. Hereīs a little graphic to show you how to connect the TX feeding. *-------------------------------------------* !solder on here =>. ! ! R ! ! ! -********- ! ! *---* IC *- ! ! -* 308 *- ! ! -********- ! ! 0 ! ! 2 ! ! 9 ! ! *--\ 6 ! ! ! ! - ! ! ! ! 5 ! ! ! ! 2 ! ! *--/ ! ! ! *-------------------------------------------* On the doughter board thereīs the biggest IC 308 (TA75W558F, 8 pins). Youīll see a track conductor from the IC to a resistance. After the resitance you have to solder on the cable for TX. Now you can connect the doughter board on the main board again. Donīt forget to solder on the pin again. 5.4 Connection a. I have a good tip (if thereīs no CTCSS unit) to construct a connection without any cables hanging out of the TH79. Get a single-breasted socket strip and a containing fitting pin contact strip. Break out 2 pieces. b. Now you have to solder the cables with the socket strip. The cable must reach to the CTCSS slide-in. c. For better remembering mark RX or TX with color. Now you can stuck the socket strip on the board, but try to stuck it, so that the CTCSS cap can be still insert. d. Stuck a bit insulating tape on the socket strip, because maybe the sheet copper will contact the pins. e. Before using the 9k6 TX/RX feature you need only remove the CTCSS cap with the fingernail or a thin screw driver. The TH79 looks like before.... 6.0 Repairing the TH79 6.1 Frequency regulator jumps ? Volume regulator scratches ? You have to take the front of the TH79 apart to remove the regulators for processing. a. Remove microphone, accumulator, antenna b. Remove the screw at the direct current socket and the little screws on the back with a fitting screw driver. c. Open TH79 and remove CTCSS cap d. For better working you have to remove the flat ribbon cable. Use a little screw driver for removing the cable out of its fastening. Now you can pull out the cable. After that remove the plug between the regulators (cable: yellow, black, red). Now you can work with the front of the TH79 fine. e. Remove volume regulator cap and frequency regulator cap. f. Now you can remove the black cap on the top of the TH79. g. Remove sealing ring of the regulators. h. Nut of the regulators can be removed with a 10s fork key. i. Remove the golden 2 screws on the board. j. Push the metal over the regulators a bit up and lift the board a bit up. Push the microphone ports a bit to the side during pulling the board up. Attention: Donīt lose the LOCK-Key. k. Now pull the plastic (under the plastic is the keypad) at the fastenings for the board up and take it away. After that youīll have the front board incl. display in your hand. l. Then you have to solder off the regulators with its mini boards from the main board. Okay, now you have the regulators incl. mini boards in your hand. 6.1.1 The frequency regulator The clamping ring below the frequency regulator must be removed. Attention: Clamping rings are perhaps jumping far away. Now you can take the inner pin out and remove the dirt with e.g. a cloth. (my pin was a bit black). Then you have to use contact spray to clean the regulator. Put the pin back again and remove it again. Repeat that as long as it will be clean enough. Now the regulator will not jump any longer (hope so) Be carefully when you solder the regulator back again. 6.1.2 The volume regulator Pull up the pin of the regulator to use contact spray. Rotate the regulator during using contact spray. You can use it on the lower side of the regulator, too. After that the regulator will not scratch any more. Be carefully when you solder the regulator back again. 6.2 Dust behind the display? Buttons don't work? Open the TH79 like in point 5.1 described. Now you can easily wipe the display off with a cloth and freeing the TH79 from dust inside. Alternatively you can also open the display at the sides with a little screwdriver, although the TH79 is shut. You can simply clean the Keypad with soap and water. Often dust or grease under the buttons prevent contacts. 6.3 Scratched display? Try "acrylic glass & repair" paste for doing this job. Thereīs no matter to polish the inner LCD-Display heavier. After this the TH79 looks as new ... Tips and tricks pse to DG8NGN @DB0ABH.#BAY.DEU.EU or DG8NGN @GMX.DE 73 and 55 Jann from Nuremberg