From: msattler@netcom.com (Michael Sattler) Subject: Mods for Kenwood TH-78A Date: Tue, 4 Jan 1994 07:45:26 GMT ----------------------------------------------------------------------------- The Complete (and Mostly Accurate) Guide to Undocumented Features of the Kenwood TH-78a Handheld Transceiver 28 Dec 1993 ----------------------------------------------------------------------------- PURPOSE: This file contains descriptions of all the undocumented features of the TH-78a I could find as of this date. It doesn't attempt to explain anything covered in the manual, but it does pass on pointers to interesting uses of documented features (such as using message write 0 as a start-up screen). VALIDITY: This file supercedes the following: th78a-0.mod, th78a-1.mod, th78a-2.mod, th78a-complete.mod, th78a-new.mod, th78a-warn.mod. I've run this file by the authors of those mod files, where I could find them. Be assured that you have the best information about the TH-78a we could put together. WARNING: This information is furnished without guarantee or warranty. Working with surface-mount diodes is delicate work. Or as Eric Williams (wd6cmu@netcom.com) so eloquently says "Lawyer bait: If you screw up your radio, it's your own damn fault, don't blame me. (But it worked on mine.)" These modifications (mods) may or may not work on your particular unit according to Kenwood. I certainly accept no responsibility for your handiwork or your transmitting on frequencies that you're not allowed to. You may have good reasons to transmit outside of ham bands as I do during search and rescue work (typically on CLEMARS, NLEMARS, and CALCOORD). ACCURACY: Please mail me (Michael Sattler, KE6DZF) at msattler@jungle.com if you see any omissions or mistakes. Make sure to pass along the date of the version you're seeing (it's just under the title). THANKS: Thanks be to all those who helped me, including George_Lin@mindlink.bc.ca, Brendan_Hoar@notes.pw.com, rfc@allegra.att.com, wd6cmu@netcom.com, elendir@enst.fr, nyu@flute.aix.calpoly.edu AVAILABILITY: I'll attempt to have the latest version of this file (named "th78a.kensho.mod") placed at the following mod servers: Server Directory ------------------------------------------------------- ham.eetech.mcgill.ca /pub/ham-radio/mods (aka atlas.eetech.mcgill.ca) bubba.business.uwo.ca /mods/ garfield.catt.ncsu.edu /pub/hamradio/HAM_MODS kilroy.jpl.nasa.gov /pub/hamradio/Mods ftp.geo.brown.edu /pub/hamradio/rigmods (no longer accepts anons) And one mail server: pcserver@novell.business.uwo.ca examples of main body email requests are as follows: HELP SENDME RADIO MODS SENDME TH215 MODS SENDME ALLBAND MODS SCOPE: Ever since this guide has been loosed on the net, every so often [someone] asks: >Would you happen to know a similar list for the Kenwood TH-77A (next one >back) Hand Held or the TM-721A (way back) mobile radio? I would not know about radios other than the one I own, sorry. I compiled this guide from old mod notes, tidbits I found on the net, and personal experience. I'm guessing that there are others out there that have done the same for their radios; I suggest that you look through all the mod servers. (If you know of other mod servers, please let me know.) ----------------------------------------------------------------------------- Contents of this file What is a "new" TH-78a? Basics of modifying the Kenwood TH-78a Potential case design flaw C-17 design flaw Mutually exclusive mods The "beyond MARS" mod The "CAP/MARS" mod The "extended receive" mod The "cross-band repeat" mod Toggle SHIFT button function Toggle CALL button function Observations on post-mod performance Cloning Cellular Telephones Battery life on the TH-78A The TH-78A (USA) vs. the TH-78E (European/Japanese) CTCSS Frequency range differences Customizing the start-up message TH-78a loses the call channel CTCSS tone Stuff that didn't fit anywhere else Game Mode ----------------------------------------------------------------------------- What is a "new" TH-78a? Kenwood says that any TH-78a with a serial number greater than 405xxx is considered a "new" TH-78a. I've not authoritatively determined the difference between the old and new models, but the mods differ, so it's worthwhile to check the serial number. The ARTSCI 5A techmod book calls this the "Later Model (with green jumpers)". I use the terms "early model" and "late model" throughout this document. William_A._Kirsanoff@smtpgty.anatcp.rock says: "I can tell you the difference between an "old" and "new" TH-78A. The "old" 78As had a fault in the microprocessor resulting in an inability to store a pl tone in the call channels (and possibly some other bazaarities). People who complained got the new processor installed by Kenwood when it became available (there are actually 2 microprocessors in the HT, I think the one changed is IC 5, mine has a paper label pasted over it). It seems they also added the jumpers on the programming diodes, probably to keep hams from using their soldering irons on the SMC diodes while making mods. :-) When my "old" unit was upgraded to the new processor, my mods from removing the diodes remained in place." ----------------------------------------------------------------------------- Basics of modifying the Kenwood TH-78a To open the radio, follow the instructions on page 64 of the manual. (Unscrew four screws and break apart the radio halves.) The two TX/RX busy indicators (LEDs) have rubber seals placed over them. These have a tendency to fall off when opening or closing the radio. All position references in this document assume that you are looking at the CPU board with the rotary encoders and TX/RX busy indicators at the top. If you have installed the ME-1 EEPROM, I recommend that you temporarily remove it to facilitate access to the diodes. You'll see a brass shield about one centimeter square covering the processor chip and the surface-mount diodes on the back half of the radio. De-solder the shield's four corners and remove it. (I used an right angle surgical tweezers in conjunction with the pin-point soldering iron to lift the brass shield.) Uncovered are the processor (which we ignore) and six surface-mount diodes, numbered sequentially from one through six (D1 - D6), top to bottom. These are about one millimeter wide; remember the note about skill and finesse. New model radios also have two large loops of green wire, numbered one through two (W1 - W2), bottom to top. You'll need a pinpoint-tip soldering iron and some braid to wick away the solder before you lift out the diode. Alternatively, Rich Garcia (n2czf@wt3v.nj.usa) suggests leaving the diode in place. "I found if you BRIEFLY touch the iron to the right side lead while gently pulling up on the SMC diode it should completely come off without needing to apply heat to the other side and further risk board damage." After you perform some or all of the mods listed below, replace the brass shield and re-assemble the radio. Then reset the processor (as documented) and re-enter any frequencies into memory. ----------------------------------------------------------------------------- Potential case design flaw >From wb1e@k1rqg.me.usa.na (which no longer exists): In the course of performing mods on my Kenwood TH-78a dual band handheld, I've discovered a potential flaw in the case design. While handling my walkie one day (after the mods were done), the display went blank and I could not turn the radio back on. With the radio split in half again, I could turn the radio back on but discovered all the memories were erased. The cause turned out to be some component pins on the front face coming in contact with the square bodies of the two volume/channel/squelch switches, when the case is screwed back together snuggly. I placed small strips of electrical tape on the sides of the switches to insulate, and reassembled; problem solved. Now I have to reprogram the darn thing.... molson@bml4380.cpg.cdc.com (Mark Olson) said: There is a warning on some of the rig mod bulletin boards about this. The problem is that pins on the back side of the PCB that is mounted on the front half of the TH78 can come into contact with the volume control housings mounted on the PCB on the other half of the unit. My radio had this problem until I put electrical tape across these housings. Symptoms were: Display blanking momentarily and the unit power cycling, sometimes causing memory erase, when pressure was applied to the front of the unit or to the volume controls. I originally thought that it was a loose battery connection... Open up the radio and you will see what I mean... Believe me, the fix is simple and it works. ----------------------------------------------------------------------------- C-17 design flaw William_A._Kirsanoff@smtpgty.anatcp.rockwell.COM said: "The 78A WILL lose C-17 on the control board if dropped, period. This causes loss on receive audio on the left-hand side of the radio. The solder pads for that cap are not big enough. If you find the need to replace C-17, use a gap-fill cyanoacrylate glue like Zap-A-Gap (tm) to increase the device footprint. I have learned the hard way. Otherwise, I have found it to be a fine radio. My only problems have been related to the C-17 issue and attempts to rectify it. Had I been given the above advice, it would have been a one-time only issue. As it is, I took out one of the microprocessors yesterday looking for a bad solder joint that was induced by my attempt to solve the C-17 problem (sigh). This radio gets a lot of use and a lot of travel. C-17 is the only thing that I have broken with the case closed. :-)" ----------------------------------------------------------------------------- Mutually exclusive mods Some of these mods are reputed to be mutually exclusive. You must choose one of the following levels of performance: The "beyond MARS" mod - gets you the widest tx/rx The "MARS/CAPS" mod - halfway there The "extended receive" mod - more of a good thing plus The "cross-band repeat" mod - a repeater that weighs almost nothing There is no mods that manipulate diodes D1 or D2 (I've seen it suggested elsewhere that this is toggles the USA/Europe-ness). Brendan_Hoar@notes.pw.com suggests: "I think removal of D1 causes "Forced Channelized Mode", at least on the "new" radios. If you put both VHF and UHF memories into a TH78A without D1 and power on, you are stuck in channel mode until you do a full memory reset. Remember, you can't add frequencies or do any tuning in channel mode. If you think about it, you'll want to be very careful not to let D1's circut become an open circut." The "beyond MARS" mod: --------------------- This mod provides the widest possible range of tx/rx. The mother of all TH-78a mods. To mod (early model): remove diode D5 only. To mod (late model): remove diode D3 and cut wire W1. D5 has priority over D3, so if you've already made the mods for the old model (which included the removal of D5) you must resolder D3 into D5. Yields RX 50-179.995, TX 136-179.995, RX 300-399.995, RX 400-511.995, TX 400-511.995, RX 800-999.995. To use: buttons operate the same way as described in the "extended receive" mod, except that you can transmit on a much wider range. NOTE TO ALL: I haven't been able to verify the actual operation of my radio on all these freqs. Kenwood talks about the difference between the "dialable" range and the operating range. I'd like to come up with a chart for each level of mod that combines the above and the two following offerings. Help me, please. * * * * * * * * * * * * * * * * * * * * * * * * * * * * Left VFO Right VFO 50.000-85.2x (with beep) 50.000-110.xxx (with beep) 85.2x-179.995 110.xxx-179.995 300.00-399.975 400.000-511.9875 400.000-511.9875 800.00-999.9875 * * * * * * * * * * * * * * * * * * * * * * * * * * * * Receive Transmit --------------- --------------- 50-135.995 (AM) VHF (NA) 136-179.995 " 136-179.995 300-399 (AM & FM) " (NA) 400-511.99 SUB-UHF 400-511.99 400-511.99 UHF 400-511.99 900-949.9875 " (NA) 50-179.995 (FM) SUB-VHF 136-179.995 The "CAP/MARS" mod: ------------------ This doesn't cover as much room as the beyond MARS mod does, but may be more appropriate for those who use the CAP or MARS frequencies. To mod (both early and late models): remove D6 only. Yields RX 118-173.995, TX 142-151.995, RX 400-511.995, TX 425-454.995. The "extended receive" mod: -------------------------- This is the mod that's usually given to hams to pacify them (the beyond MARS mod is closely guarded). To mod (both early and late models): remove diode D5. To use: press 'F' for one second and then pressing the Band button will switch the UHF VFO to a 800-999.995 MHz band and the VHF VFO to a 300-399.995 MHz band. The regular VHF VFO can now receive down to 50 Mhz. The "cross-band repeat" mod: --------------------------- Allows you to... (WHAT!?!) To mod: remove diode D4. To use: press 'F' for one second, then '0'. Repeat to disable. The MHz dot will flash when in repeater mode. ----------------------------------------------------------------------------- Toggle SHIFT button function Press SHIFT during power-up This is described in the manual, but the documentation is not complete. The TH-78A can operate in two modes: In SPLIT mode, non-standard offsets (i.e. split frequencies) are supported, but the default offset is not programmable. In SHIFT mode, non-standard offsets are not allowed, but the default offset is programmable. To select the default offset, press F for 1 second, then SHIFT. See p. 30 of the manual for details on changing the default offset. ----------------------------------------------------------------------------- Toggle CALL button function Press CALL during power-up. The CALL button can operate in one of two modes. In the default mode (CALLSW), it switches between the call channel and the last memory channel (if in memory recall mode) or last frequency (if in VFO mode). After toggling the CALL button functionality (VMC), it will switch from the VFO to the last memory channel and then back to the CALL channel. ----------------------------------------------------------------------------- Observations on post-mod performance Rich Garcia (n2czf@wt3v.nj.usa) observes "all original functions have maintained the same which is great. Aircraft band which was accessible before the mod remains with the same characteristics. It seems that VHF-High band has improved a bit on sensivity where it was dead as a dog before the mod (above 155.000MHz) but the 162.000 MHz band where weather radio is is still a bit deaf for reception at any distance but about 20 Miles. This depends on your (or my) terrain and transmitter output power. "On UHF all public safety frequencies up to about 500 MHz seem to come in well but sensivity greatly drops from there (we really can't ask for more). Frequencies can be programed in up to the 920MHz ham band but I have no way of measuring sensivity. 800MHz works but the signals are very weak, you must be near the transmitter for reception. Assuming you are in the town or city where the transmissions originate it should work. "Transmit is enabled up to and incl. 500MHz but after testing this on a frequency counter I find that a signal is only generated to about 490 MHz, even though the trans. LED shows output in the higher frequencies. "Crossband repeat seems to work fine but the audio is unacceptable for use, BE AWARE the radio gets HOT! Prolonged use or use on a busy frequency would not be recommended. Also remember this is a dual band HT please use a proper antenna while in this mode to avoid a high SWR, we should all know better... Right?" Someone else said: "I found that marine weather reports at 162.40MHz in my area were received much better on the SUB-VHF band, than on the VHF band... "If you are having problems with intermod, try switching bands (i.e. using the SUB-VHF band rather than the VHF band.)" ----------------------------------------------------------------------------- Cloning The TH-78a's memory can be copied from one TH-78a to another TH-78a entirely through radio waves "over the air" (i.e. without cables or other special equipment). Theoretically, this could be done via repeaters, although I've never heard it done. Allegedly this requires a mod that includes removal of D5 or D6, but I haven't researched it. Cloning is a real boon to groups that want a bunch of radios to contain the same memories, such as amateur radio clubs, search and rescue units, and people too lazy to program their radios. Of course, given that the ME-1 memory expansion unit has 250 memories, laziness is understandable :-) (1) Set both radios to the same frequency. (2) Activate both radios by pressing the '0' key while turning the power on. The radios will display the word "clone". (3) Now, click the PTT button of the "master" radio. The radio will transmit in the economy low power mode. This may take about 4 minutes for fifty channels, or 20 minutes for the 250-memory ME-1. When the data has been transferred, both radios will revert back to their original frequency. (It is recommended that a dummy load be used to prevent unwanted interference.) (4) Turn both radios off and then on again. The slave is now a mirror-image of the master radio. ----------------------------------------------------------------------------- Cellular Telephones Cellular phones operate at (tx) 824.040 - 848.970 (rx) 869.040 - 893.970, within reach of your modified TH-78a. The increments are, however, every 30kHz; the TH-78a will only increment in 25kHz steps at this frequency range, so the exact cellular frequency cannot be tuned in (most of the time). ----------------------------------------------------------------------------- Battery life on the TH-78A wd6cmu@netcom.com (Eric Williams) says: Some people have complained about the battery life on the TH-78A. I came up with these tips by checking out the power consumption under various configurations. In the case of power-saver mode, figuring out the average current with my DVM was impossible, so I ran the radio on a large capacitor and timed how long it took to die. These tips won't solve everything, but they might help. The rig draws close to 2ma even with the power turned off, so don't leave the rig off with the battery installed for several days and expect full capacity to be maintained. If you're only using one of the bands, shut down the other to extend your battery's life -- current consumption with the squelch closed is cut by almost a third. If you're monitoring two frequencies on the same band, use the f2 button to receive both simultaneously rather than scanning between them -- the battery saver with two receivers will use about half the current of one receiver that is scanning. You can make up a battery pack by putting nickel metal hydride AA cells in a BT-8 battery holder. A small strip of aluminum from the positive battery terminal to the depression in the top of the case will allow you to recharge the pack inside the rig. This will give you 1000mah capacity without enlarging the size of the radio, and NiMH cells have no memory effect. (But they *are* expensive.) ----------------------------------------------------------------------------- The TH-78A (USA) vs. the TH-78E (European/Japanese) CTCSS: ----- Eric Williams (wd6cmu@netcom.com) reminds us that: >The manual says that the CTCSS module is an option on the >European model, but standard on the U.S. one. Vince (elendir@enst.fr) replies: >That's ... because [the French] repeaters are activated by >a 1750-hertz tone. If I intend to go to US this summer, >must I buy the CTCSS module ? biocca@csg.lbl.gov (Alan K Biocca, WB6ZQZ) says (and I paraphrase): >While it varies geographically, where I am (Lawrence Berkeley >Laboratory, California) very few 2-meter repeaters require CTCSS >tones, most 440 MHz repeaters do. Many of those that do are closed >anyway. You can probably get by without them. gsm@mendelson.com (Geoffrey S. Mendelson, N3OWJ) tells us: >It depends on where you are. In the Philadelphia area most of the >open 440 MHz repeaters use CTCSS and none of the 2-meter ones do. >At least one uses CTCSS for remote inputs. > >About 60 miles away in southern New Jersey, all of the 2m and 440 >repeaters use CTCSS. Frequency range differences: --------------------------- Someone (I've forgotten who) suggested: >Um, I'm pretty sure that the unmodified UHF TX range is different. Kenneth E. Harker (kharker@bnr.ca) wrote: >These are the VHF - UHF bands authorized in France : > >50.2 to 51.2 with a special authorization. >144 to 146 >430 to 440 (shared band) Whereupon Lawrence "The Dreamer" Chen (dreamer@lhaven.UUmh.Ab.Ca) said: >In North America the authorized bands are: > >50-54 >144-148 >220-225 (222-225 in US and soon to be Canada) >420-450 (420-430 is only by special permission) and its a shared band. > >I would guess that the TH-78E only does 144-146 and 430-440 while >the TH-78A does 144-148 and 440-450. torsten@rnivh.rni.sub.org (Torsten Leibold) summarized for us: >Yep, you're right. The A version is the American version and >the E stands for Europe. The E version does 144-146 MHz and >430-440 MHz without modifications. (I guess there are some >secret codes to switch it to the "A"-bands, but I don't know >them). I don't know of any "secret codes", but I'd heard that D1 toggled between 'A' and 'E' performance. Unverified. -- msattler ----------------------------------------------------------------------------- Customizing the start-up message William_A._Kirsanoff@smtpgty.anatcp.rockwell.com says: Just in case you are doing a message write, don't pick slot '0', that would change your start-up message (default is "TH-78A", mine is "KD6MCI" :-) ) You can then crack open the manual and read up on how these features work. I use the autodialer regularly. I don't have much use for the message memory other than the start-up trick though. ----------------------------------------------------------------------------- TH-78a loses the call channel CTCSS tone George_Lin@mindlink.bc.ca says: > Michael Sattler writes (regarding George's comments): > > Can you come up with an easy procedure for the readers of the guide > to check whether their particular TH-78a loses the call channel tone? > (I want to hear what you do, rather than make something up.) Sure. Go to the oscillator on the right (UHF oscillator). Select a UHF frequency on the VFO. Set the CTCSS tone frequency to some arbitrary number, say, 94.8 Hz. Turn on the CTCSS. Save the whole thing under the call channel for UHF. Select another UHF frequency. Select another CTCSS tone. Turn the subaudible tone on and save it under a spare memory channel. Go back to the call channel and check the tone frequency. ----------------------------------------------------------------------------- Stuff that didn't fit anywhere else Early on, msattler@netcom.com (Michael Sattler, KE6DZF) mentioned: >I've had one report that the TH-78A is capable of in-band full duplex >operation. I've been unable to repeat this on my unit, which only has the >CAP/MARS mod perform. Confirmation of this feature would be appreciated. nyu@flute.aix.calpoly.edu (Neal, KD6HPG) replied: >My friend (N6RNF) has a "early" model radio and it was capable of doing >in-band full duplex. I have a "later" model of the TH-78A and I can't >get it to work on mine. My friend's radio has the beyond MARS mod. ----------------------------------------------------------------------------- Game Mode ORIGIN: aviator@athena.mit.edu (who no longer exists), who credits james@brokaw.lcs.mit.edu for "much of this". To enter the game mode press M and PTT during power-up. Be careful not to accidentally reset the memory, which happens with M + power-up. (Don't freak; you'll see the same "all screen items lit" when entering game mode as when you reset memory.) To exit the game mode at any time, press the LAMP key. The volume, lamp, or frequency settings can't be changed while in game mode. The top part of the display will show "H.00", which represents the high score. The lower part shows a scrolling message, "PRESS ANY KEY". Pushing any key starts a "Follow Simon" type game. The display will briefly show one of the characters '1', '2', '3', or 'F'. Press the corresponding key. The game consists of repeating the displayed character sequence, which increases by one character each round. After you "win" the Simon memory game by getting correctly entering a sequence of twenty characters, the next game is a draw poker game. The way it works is that you choose your bet (from 1 to 10) by pressing '2' to increment the bet and '5' to decrement the bet. Then, press 'F' to deal the five cards. The face value of the cards is displayed, and the suits can be seen at any time by holding down the PTT key. Any number of cards may be discarded, and to select (or deselect) a card for discarding, press the keys '1', '2', '3', '4', or '5'. If a card is selected for discard, it is displayed "face-down". Press 'F' again to draw new cards. Your new cards will be displayed, and then if your hand is 2-pair or better, the screen will show the rank of your hand on the left (2P for 2-pair, 4K for four-of-a-kind, etc.). On the right the pay-off for that hand will be displayed. Your bet is multiplied by the pay-off factor,and the resulting pile of cash is displayed in the right hand side of the upper screen. (The left-hand side of the upper screen contains your table stakes, which are initially 100 coins from winning the Simon game.) If you win the poker hand, pressing any key steps into the next stage. If you lose the poker hand, your bet is deducted from your stakes and you are asked to start another poker hand. In the next stage, you are asked "TRYB/S" which means, "Do you want to try double-or-nothing in a guessing game for Big or Small cards?" Press 'F' for yes, press TONE for no. If you say no, your winnings are credited into your stakes and you are asked to start another poker hand. If you say yes, then a single shuffling/incrementing card is displayed on the left, and three stars are displayed on the right. You have to choose to go for either BIG or SMALL, by pressing '2' or '5'. You can keep pressing '2' and '5' to change your mind. When you are ready, you must try to hit the 'F' key to stop the rotating card display, and the card will show, and you will either win, lose, or draw. If you draw, you have to play big/small again, I think. If you lose, your winnings are gone and you can play poker again. If you win, your winnings double and you are asked whether you want to play big/small again. The payoffs on the poker are set against you, odds-wise; the double-or-nothing game includes a draw, so the odds are against the player there unless you can time hitting the 'F' key to win more than half the rounds. I haven't managed to do this, so I don't know if there is anything beyond this, all I know is that when the table stakes are exhausted, you go back to playing Simon again. ----------------------------------------------------------------------------- This is the end of The Complete (and Mostly Accurate) Guide to Undocumented Features of the Kenwood TH-78a Handheld Transceiver. ----------------------------------------------------------------------------- -- ------------------------+------------------------+--------------------------- Michael Sattler, KE6DZF | All that is required | Encrypt now; ask me how. Digital Jungle Software | for evil to triumph | Finger for PGP key. msattler@jungle.com | is for {wo}men of good | GCSy+n+f+g+t+d--p--c++u+ +1.415.621.2903 | will to do nothing. | e+m++s++/rhw!l