TS-440S Digital Audio Modification
TS-440S Digital Audio Modification
Please be very careful with your transcievers, and we accept no responsiablity for any damage that may be incurred, and this
modification may, and proably would be cause for any WARENTY to be DISCONTINUED.
This Modification allows for the Kenwood TS-440s transceiver to have the data audio on PIN 11 of the 13 pin DIN connector ACC JACK
2. Later models may or maynot have a correction for this, but my PK-232, or for that fact NONE of my TNC's would drive the audio to
the PIN 11 of ACC JACK 2. Encountering this problem, and having another H.F. transceiver I have been using the REMOTE connector,
and using an audio input to the AFSK IN RCA type connector. This would allow me to use the same cable with my TS-180s also.
Anyway this modification moves the wire's from the AFSK IN to the ACC 2 connector. This should only take about 20 to 30 minutes to
preform this change, and most of the time is used up with the removal, and replacement of the THREE covers of the transceivers
The circuit boards to work with, are called:
DISPLAY UNIT (X54-1870-00) (C/4) This has the ACC 2 JACK.
SWITCH UNIT (X41-1610-00) (M/14) This has the AFSK INPUT.
The eaiest way is to remove these two boards 4 screws hold the ACC 2 JACK, and 2 screws hold the AFSK INPUT board in and they are
located at the rear of the transceiver. If you are interested in following the SCEHMATIC in your manual, the leads you will be working
with are ANI, and GROUND which is the PURPLE LEADS, and the FSI lead and GROUND, which are the GREEN leads.
The problem is that when kenwood designed this rig, they brought the DATA INPUT(ANI) from the ACC2 JACK to connector J25 of the
This coming in after the Processor, and Microphone Amplifier does not allow sufficent amplification of the signal, thus very low, or no
audio at all. What this modification does is swap at the rear of the RIG the FSI, and ANI signals, Which also could be done on the IF
UNIT board, and for some may actually be eaiser. In my case the leads were just a bit too short to allow this modification to be
accomplished on the IF UNIT.
1. Be shure to have on a work bench, and NO POWER APPLIED!
2. Remove the TWO BOTTOM covers, One MAIN cover, and the smaller cover to the REAR of the transceiver.
3. Remove the TOP cover.
4. Remove the FOUR screws holding the AUTOMATIC ANTENNA TUNER.
5. Place the transceiver on it's side with the BOTTOM towards you, and the FRONT to your LEFT.
6. Being very careful, remove the antenna tuner and allow it to hang.
7. Remove the TWO SCREWS that HOLD the AFSK INPUT board.
8. Remove the FOUR SCREWS that HOLD the ACC 2 JACK board.
9. Carefully from the inside of the transceiver, pull these TWO boards out.
10. Near the Bottom edge of the ACC 2 JACK board, is a TWO lead connettor, unplug this. The leads should be PURPLE.
11. On the AFSK INPUT board, there is a 6 PIN connector, unplug this. The leads you will be working with are GREEN in color.
12. Note how the PURPLE leads are connected to the connector itself, and remove these two leads by inserting a very small
screwdriver into the slot on side, and being very gental, push the leads out one at a time.
13. Now remove the GREEN leads the same manor.
14. Insert the GREEN leads into the 2 PIN connector, the BLAC lead is the GROUND, and the WHITE or perhaps YELLOW is the AUDIO
15. Insert the PURPLE leads into the 6 PIN connector, noting that the smaller lead is the AUDIO lead, and it connects to PIN 2, the
other lead, being BLACK goes into PIN 1.16. Now reassemble in reverse order the BOARDS, and start at STEP 11, and work in reverse to STEP 1.
GW1NGL NA7KR Kevin Roberts Ham Radio
Page last updated on 09/10/2012 by Kevin Roberts NA7KR a colection of Ham Radio and Electronic Information