TH78A.6

Date: 22 Oct 92 15:38:10 EDT (Thu)
From: n2czf@wt3v.nj.usa (Rich Garcia)
Subject: TH-78A Modification File

FILENAME:TH-78A.MOD                     June 25,1992
Revised: October 22, 1992
Modifications for the Kenwood TH-78A Dual Band Micro-HT.
By Rich Garcia N2CZF.   Packet Via N2CZF@WT3V.NJ.USA

Owner assumes all responsibility for modifying or using these
modifications!.

The following mods will provide for Crossband Repeat and extended
receive and transmit on the Kenwood TH-78A HT.

I believe other functions are also enabled by these mods. which I
have not found yet but I will update the file as news progresses.

Diode #4-  Crossband Repeat
Diode #5-  Extended Receive and out of band Transmit.

Remove all screws and open radio as explained in the Kenwood manual
for installing the memory expansion module.
On the back cover you will find the memory expansion module socket
and a copper shield to the upper left corner of it.
Under this shield their will be a row of SMC diodes which are
unmarked in a vertical configuration to the lower right portion
covered by the shield.

#1 Remove the shield at it's four corners with a solder sucker and
SMALL! iron.

#2 Carefully count down from the 1st diode in the row to the fourth
one and remove for crossband repeat.
HINT: 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.
I used a pair of right angle surgical tweezers for this.

#3 Just as above you may remove the fifth diode to preform the
extended receive and transmit modification.

#4 Reset the CPU (yes you will loose all of your programed
memories! argh!) by pressing Function for more than one second and
then "0".
YOU HAVE NOW COMPLETED THE MODIFICATIONS!

#5 For 800Mhz go to the UHF band with the band switch and press
Function for more than one second quickly following with a press of
the Band switch again.  8---.-- will appear.

#6 For 300MHz go to the VHF band and repeat as above.  Original
bands are restored by repeating the "F Band" sequence.

MY observations...   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.
CONTINUED IN TH78A.7