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
n1jhw
ma0226


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


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.