Kenwood TH78A Instructions

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I uploaded the following texts to the old norcal AX.25 packet network way back around 1992. I put the

information together from various sources and included the receiver sensitivity measurements I did

after modifying my TH78A. The upload capacity of the network was pretty small back then so each file

needed to be kept small. I am leaving them in the original order for posterity but editing the layout to

be more readable since they were originally plain text. You can still find the archive of the original 16

files that comprised the mod list is you search hard enough. Ken Mazie (KD6IZY)

These are modifications for the Kenwood TH-78a dual band hand held radio. They have been compiled

through correspondence with Kenwood, and tidbits picked up here and there. The author assumes NO

RESPONSIBILITY for these mods or what they do to your radio, or what YOU do to your radio attempting

to perform them. In other words, you break it, it's your fault.

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CROSSBAND REPEAT:

The user manual claims the unit will cross band repeat out of the box, this is not true. For the TH-78a to

cross band repeat you must remove diode D4. Unfortunately you need to reset the CPU which will clear

your preset memories (NOTE: See "cloning"). Write down what you have programmed into the TH-78a

and then hold down the "M" key and power up the unit. All LCD segments should light up. The CPU is

Kenwood TH78A Mod Instructions

The Kenwood TH-78A is a sophisticated dual-band for 144 and 440 MHz. It

has built-in DTSS and paging functions, alphanumeric memory and

message paging. Additionally it has dual-frequency receive capability

(including VHF+VHF and UHF+UHF). There are 50 multi-function memory

channels plus 2 call channels (the optional ME-1 increases the memory

capacity to 250 memories). With alphanumeric tagging the memory

capacity is 25 channels (or 125 with ME-1). The operator can choose from 8

different scan types for each band (with carrier or time operation). DTSS

allows DTMF access to the transceiver. The TH-78A features a two line LCD,

10 minute time-out timer and backlit keypad.

The receive range of this HT is: 118-173.995 and 438-449.995 MHz. Three

RF output levels are provided. On 144 MHz with external power output is:

5.0/0.5/0.02 watts. On 440 MHz with external power output is:

5.0/0.5/0.01 watts.

1.95x5.28x1.61 inches 0.88 Lbs. (50x134x41mm 400g)

KENWOOD TH-78A MODS

Page 1 I did after modifying my TH78A. The upload capacity of the network was pretty small back then so each file needed to be kept small. I am leaving them in the original order for posterity but editing the layout to be more readable since they were originally plain text.
Page 2 now reset and to use cross band repeat hold the "F" key for longer than 1 second, then press the "0" key. The decimals in the displayed frequencies will flash indicating cross band repeat. End of part 1..============================================================================= EXPANDED FREQUENCY COVERAGE: The TH-78a will receive far beyond its factory settings.
Page 3 End of part 3 ============================================================================== PERFORMING THE MODS: To open the radio remove the battery, then remove the 3 #0 Phillips screws from the back, and the one from the side. Flip over the radio and press up on the inside of the back cover. Be careful with the LEDs on top.
Page 4 950.000 1.90 microvolts Anyone with more info on the TH78a, please send it my way and I'll add it to this file. I can be reached at the following locations: Ken Mazie - Sysop, Quasatron Systems BBS (landline) at 510-846-6085.