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-
- Subject: The Complete Guide to Undocumented Features of the TH-78A
-
- The information contained in this document is derived from many sources.
- Unfortunately, I have not kept track of everyone who has provided input,
- but I would like to thank those who have helped me compile this
- information.
-
- This document is probably not complete: Please send any additions or
- corrections to aviator@athena.mit.edu (Internet) or
- n1jhw@ka1srd.#ema.ma.usa.na (amateur radio packet) or
- ma0226@ma1bbs.mawg.ner (Civil Air Patrol packet).
-
- 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.
-
- Please Note: I can take no responsibility for any problems which may be
- caused by attempting to access one of the features described here. This
- document may be distributed in its original form only, and not via packet
- radio.
-
- 1. Hardware Mods
-
- Hardware modifications for the TH-78A are performed by manipulating a
- series of 6 surface mounted diodes, identified as D1 through D6. The
- TH-78A block diagram contains a table identifying 7 configurations
- involving D2, D3, D5, and D6. However, none of the configurations described
- below are included in that table.
-
- To open the radio, follow the instructions on p. 64 of the manual. 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.
-
- The diodes are located on the CPU board, which is mounted inside the front
- panel of the radio. The CPU board is readily identified by a brass shield
- covering the CPU, as well as the socket for the ME-1 memory expansion chip.
- 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.
-
- The diodes are located in a vertical row just below the lower right corner
- of the brass shield. The diodes are numbered sequentially, starting with
- D1 at the top.
-
- The U.S. stock configuration has all diodes in place. The function of D1
- is not known at this time. D2, D3, D5, and D6 are thought to control TX
- and RX ranges. D4 controls cross-band repeat.
-
- Before removing a diode, Kenwood recommends unsoldering the brass shield.
- There are four solder points, one at each corner. The brass shield is
- attached to the CPU with a small piece of double-sided adhesive tape. An
- alternate method consists of unsoldering the right side of the appropriate
- diodes, which are visible underneath the shield, and bending them to
- approximately a 45 degree angle, forming an open circuit.
-
- Early Model Radios Only
- =======================
-
- CAP/MARS mod: Remove D6 only. Yields RX 118-174 TX 142-152 RX 400-512
- TX 425-455
-
- Beyond MARS mod: Remove D5 only. Yields RX 50-180 TX 136-180 RX 300-400
- [VHF side only] RX 400-512 TX 400-512 RX 800-950 [UHF side only]
-
- Late Model Radios Only
- ======================
-
- Beyond MARS mod: Remove D3. Also remove jumper W1. Yields RX 50-180
- TX 136-180 RX 300-400 [VHF side only] RX 400-512 TX 400-512 RX 800-950
- [UHF side only]
-
-
- Note: The frequency ranges include the lower limit, but exclude the upper
- limit (i.e. 118-174 really means 118.000-173.995).
-
- Crossband repeat mod: Remove D4. Apparently, this mod is independent of the
- D5/D6 mods.
-
- 2. Undocumented Features
-
- Crossband Repeat: Press F for 1 second, then 0 [requires D4 mod] Repeat the
- same sequence to disable.
-
- Wideband RX: Press F for 1 second, then BAND [requires D5 mod] On the VHF
- side this yields 300-400 RX, on UHF 800-950 RX.
-
- Sample Channels: Press DUAL during power-up Programs some sample
- frequencies in VHF and UHF memory channels (it's a pain to undo the
- sample programming).
-
- Cloning: Press 0 during power-up [requires D5 or D6 mod] Allows cloning
- over the air. All keys except PTT and POWER are disabled. Press PTT to
- send DTMF cloning sequence. Presumably, receiving TH-78A must be in
- same mode.
-
- Toggle SHIFT/SPLIT Mode: 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 th 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.
-
- ======================================================================
-
- Game Mode: Press M and PTT during power-up [be careful not to accidentally
- reset the memory (M+POWER)]
-
- [Much of this was provided by james@brokaw.lcs.mit.edu]
-
- To exit the game mode at any time, press the LAMP key. It is not possible
- to change the volume, lamp, or frequency settings 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, whic h
- 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 ke
- ys 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 wi
- nning 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/incr
- ementing 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 doub le 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.
-
-