Modifications for the Kenwood TS-440

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 cabinet.

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 IF UNIT.
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 lead.
  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.

TS-440 Fan Temperature Modification

I don't know about you, but I don't think solid state equipment needs to run hot enough to fry an egg on. The fan on the 440 is set to come on at 50 deg C. That makes the heatsink hot enough that you can only put your hand on it for about 3 seconds without being in pain.

Looking at the schematic and pondering the situation, I decided that it would be quite easy to change the "trigger" point for fan operation. This mod will do just that and not effect the "high-temp-shutdown" mode that is provided in case the fan dies. Actually, it wouldn't be a bad idea to make the same sort of mod to that circuit too, but let's just do this one for now. I'll put out another bulletin on this if I go into the failsafe circuit.

The fan is controlled by two sensing circuits on the FINAL UNIT. On the schematic, Q9(1/2) is the failsafe trigger that activates the powerdown circuit in case the final reaches 80 deg C. It won't normally do this, even under continuous keydown conditions, unless the fan has failed.
Q9(2/2) is the stage that controls operation of the fan. It is a simple voltage comparator and therefore can be made to trigger wherever you want.
TH1 is a thermistor with a negative coefficient. That is, when the temp rises, the resistance goes down. This pulls the - input to Q9(2/2) lower and lower until it is at or below the 2.26v reference that is present on the + input of the same stage. At that point, the output flips high and turns on Q8, thus turning on the fan. By raising the reference voltage at the + input, the TH1 voltage will fall to the reference voltage sooner and turn on the fan at a cooler temperature. By clipping the top loop of R27 on the final unit (2.2k res. that provides reference voltage) and temporarily inserting a 5k precision multi-turn pot in series with it, I determined that I liked the way it operated with about 800 ohms extra resistance in the circuit.

I then installed an 820 ohm fixed resistor in series with the cut loop. I also put a very small dab of silicon seal between the new "hung" resistor and the ferrite transformer right next to it so that there would be no added strain on the remains of R27. The alternative would be to remove the final unit completely and do the mod the right way, replacing the complete R27 with a 3k resistor. This was a step that I didn't really want to perform on a two week old rig. When you choose your series resistance, remember that the more resistance you add to it, the sooner the fan will turn on. If you go too high, it will be on all the time.

This modification brings the fan on at least 10 deg. earlier. By the way, my only reservation about this mod is the added wear and tear on the fan unit itself. I have been buying parts from Kenwood for about 10 years now and they have always seemed remarkably inexpensive. Ordering a spare fan to have on hand seems like a very reasonable thing to do if you are worried about it.
Possible cure for TS440 showing dots only on display

The most common reason for the the display to show only dots, is that one of the phase locked loops is not locked. So take of the top cover. You will be looking at the IF unit. This board is mounted in a hinged frame. It hinges on two screws near the front pannel sides. So remove the other two screws near the final unit instead and hinge the IF board towards you. You now uncovered the PLL unit.

There are five PLL's on this board. Each one has a pin indicating if its loop is locked or not. So get out a volt meter and set it for 5 volts full scale. Now check pin 2 for each of the following IC's. IC18, IC1, IC4, IC9.
Also check pin 7 of IC17. If all the loops are locked, you would see a steady voltage there in the neighbourhood of 4.7 volts. If any of the loops is not locked, one of these pins has a voltage well below 1 volt.
Note the IC number so you can look up which VCO you may have to tune a bit so it will lock again.
IC18  VCO#5 T20
IC1   VCO#4 T1
IC4   VCO#3 T2
IC9   VCO#2 T9
The above are all located on the PLL board.
The VCO for IC17 is actualy one out of four different VCO's selected on the RF board. Which one of these depends on what band is selected.
If you have display dots on all the bands, then you have no problem with the PLL made up with IC17. So you only have to adjust either T1, T2, T9 or T20.

Now here it goes. Make sure you have an alignment tool that isn't to small or to large for the slots in the slugs in the coils (T1, T2, etc.) Also, absolutely don't turn any other coil than the one that belongs to the unlocked PLL. If you do so anyway without a service manual and proper equip- ment, then you are likely stupid.

Only turn the indicated slug. First turn it 1/4 clock wise and see if it is ok now. If not, turn it 1/4 counter clockwise and see if it works. I suggest that you don't try more than one half turn either way. If you think that it needs to go that far, it likely has an other problem.

If the display dot problem only shows up on some but not all band, send me a note and I will see if I can help you.

The correct way would be to use a good voltmeter and follow the service manual for this adjustment. But in most cases, the above will do fine. I don't work for Kwood, I don't have a 440. Just a service manual for one. But I did cure some of the above problems.
Undocumented feature

The TS440 is nice. Here's what I've found out about it that isn't in the operation manual (in some random order):

Diode options: There are a bunch of configuration options controlled by clipping or inserting diodes on the back of the control board. You get to it by taking the top and bottom covers off (a bunch of silver screws), loosening the front panel (4 flat-head silver screws, NOT the black ones). Then you have:

   diode        controls                in              out (cut)
   -----        --------                ----------      ----------
   D65          mode confirmation       Morse           single beep
   D66          display resolution      100 Hz          10 Hz
   D67          memory protect          none            on
   D73          CW shift                800 Hz          400 Hz
   D78          WARC 24MHx band tx      disabled        enabled
   D79          WARC 18MHz band tx      disabled        enabled
   D80          General Coverage tx     disabled        enabled
Self-Test: You can run a rather complete test of the control logic by the built-in "semi-self-test", a series of 56 routines. To run this, turn the unit on whilst holding the AM and T-F SET switches pushed in. It changes to the next test when you turn the VFO knob clockwise. Turn the power OFF to reset the unit.
   Test         What it does
   ----         ---------------------------------------------------
     0          all positions in display light
     1          all segments in display dark
     2          all positions in display light
     3          all segments in display dark
     4          one digit lighted (rightmost)
     5          next digit lighted
     6          next digit lighted
     7          next digit lighted
     8          next digit lighted
     9          next digit lighted
    10          next digit lighted
    11          next digit lighted
    12          next digit lighted
    13          next digit lighted
    14          next digit lighted
    15          next digit lighted
    16          next digit lighted (leftmost)
    17          beeper sounds
    18          beeper silent
    19          all mode LEDs ON
    20          all mode LEDs OFF
    21          receive 
    22          transmit
The following tests change internal signals. They are most useful if you are trying to trace the circuits controlled by these signals.
You'll need a s service manual (or at least a schematic) to made reals sense of these.
    23          Band select - all lines high
    24          BAND select - all lines low
    25          PD select - all lines high
    26          PD select - all lines low
    27          ENF select - all lines high
    28          ENF select - all lines low
    29          ENP select - a:ll lines high
    30          ENP select - all lines low
    31          RES select - all lines high
    32          RES select - all lines low
    33          CO select - all lines high
    34          CO select - all lines low
    35          AX select - all lines high
    36          AX select - all lines low
these next tests check the outputs of the 8255 parallel port interfaces, which select several internal functions.
    37          (IC2) port A all lines high
    38          (IC2) port A all lines low
    39          (IC2) port B all lines high
    40          (IC2) port B all lines low
    41          (IC2) port C0-C3 high, C4-C7 low
    42          (IC2) port C0-C3 low, C4-C7 high
    43          (IC53) port C all lines high
    44          (IC53) port C all lines low
Following display busy lines and scan lines in the rightmost 9 digits of the display. You will push buttons to cause the digit to change from a 1 to a 0 indicating that the associated button has been pushed.
 test   bit8    bit7    bit6    bit5    bit4    bit3    bit2    bit1    bit0
 ----   ----    ----    ----    ----    ----    ----    ----    ----    ----
  45    LOCK            AT      Mic UP  Mic DN  PTT/AT                  VS1
  46 (none)
  47 (key scanner)
  48     1       6      V/M                     VOICE
  49     2       7      M>V     RIT             A/B
  50     3       8      SCAN    XIT             SPLIT
  51     4       9      M.IN    T-Fset          A=B     dip3    dip4    dip5
  52     5       0      CLEAR   1Mhz            dip1    dip2    dip6    dip7
  53                    ENT     DOWN            UP      dip8    dip9    dip10
(the digits 0-9 are on the front panel keyboard; dip2-dip10 are the segments of S50, the SSB frequency response dipswitch on the rear of the control unit printed circuit board.)

54 not used
55 not used
56 END
Serial interface

The TS440 has a serial ASCII interface option. You have to insert two chips into sockets on the back of the control unit circuit board to take advantage of this. IC54 is an 8251A Uart, and IC55 is a CD4040 divider. These chips are available from Kenwood together with a interface manual, or you can buy them at your local chip shop for about $6.00 or so. When inserted, the transceiver speaks 4800 baud ascii in/out the 6-pin DIN connector ACC-1 on the rear. The signals are from the 8251, but are inverted in a 74LS04 and RFI filtered before being brought out to the world. An interface box with inverter, RFI filter, power supply, opto-isolator, RS232 level shifters, and power supply is available from Kenwood for about $49.00, or you can build your own.

(Depending on how much your computer radiates and how sensitive to RF it is, you may only need 5v, +/-12v, a 74LS14, MC1488, and MC1489. If your computer has a TTL level serial port, perhaps all you'll need is the 74LS14. If you're not confident of being able to solve the possible digital/RF interface problems yourself, the $49 interface is proably a good buy.)
                ACC-1 Serial Interface
        pin     signal
        ---     ----------------------------------------------------
         1      signal ground
         2      data from transceiver
         3      data to tranceiver
         4      cts to transceiver - computer can throttle output
         5      cts to computer - transceiver can throttle input
         6      no connection
SSB frequency response dipswitch: located on the back of the control unit, this adjusts the frequency response of the upper and lower sideband modulators to compensate for component variations. Changing it isn't a good idea, since you have to have a two-tone oscillator and have to reset the carrier suppression adjustment if you do. The service manual explains this process; I'm including this here so that people who have been wondering what the dipswitch does won't screw themselves by flipping switches to see what happens.
A few adjustments you should know

A few adjustments you should know about (read the service manual before you tweak wildly on these!):

        tweaker         what it does
        -------         -----------------------------------------------
        RF-VR3          FM Microphone Gain
        RF-VR6          FM Deviation - set to 4.6KHz on dev meter
        IF-VR2          S-meter zero - set to zero with 50 ohm dummy load
        IF-VR3          S-meter S9 - set to S9 with 40dbu input 14.175MHz USB
        IF-VR4          Squelch threshold - close at 12 o'clock with
                        mode = CW and filter WIDE
        IF-VR9          CW side tone level - as you like it
        IF-VR10         Beep tone level - as you like it
Someone wanted to know what the difference between the DATA connections on ACC-2 and the AFSK connectors was. On output, none; the AFSK and the DATA out pin on ACC-2 are connected together, and are fed from the high side of the volume control - they are receiver audio BEFORE the cw sidetone, beeper, and voice response unit are mixed in, and should be a constant level independent of the AF gain setting. The AFSK input is different from the DATA IN connection; AFSK and microphone signals both go through the mike preamp and speech processor; the DATA input bypasses both. The MIC GAIN pot does control all three input levels.
(as a note, you can tap preamped/processed audio OUT of the DATA IN connection, since it is just a tap on the output of the preamp/processor. This is also the feed into the FM modulator. But NOTE that the MIC GAIN pot doesn't adjust the mic gain on FM - there is a separate tweaker for that.)
TS-440S modification to use antenna tuner

Remove case from rig. Remove (4) screws that holds antenna tuner in place. Next slide antenna tuner out to get to the coax connections. Remove the in coax attached to antenna tunerfrom FO connector on filter unit (X51-1340-00). Remove coax from out connector on antenna tuner and install in FO CONNECTOR ON FILTER UNIT. Unplug and remove switch unit (X41-1610-00 N-14) from rig.
Remove short wire from antenna connector to PC BOARD. Cut coax on the in connector of antenna tuner in half and connect cut end to switch unit PC BOARD Where short antenna wire was removed and shield to ground. Solder other half of coax to antenna connector and shield to ground, and plug other end into out conector of antenna tuner. Your still have control of antenna tuner with auto and thru switch. It works very well. Maybe someone can use this idea.
TS-440S display calibration

I found there was some shift in the reference oscillator frequency of my TS-440S. This can be noticed and corrected as follows:
  1. Remove the top and bottom covers from thd radio.
  2. Do not disconnect the speaker cable.
  3. Connect the supplied calibration cable between RF Unit and PLL unit, as shown in "Kenwood TS-440S Instruction Manual" on Page 24 in Section 5-8-3.
  4. Set VFO A to 10.001.00 MHz LSB and VFO B to 9.999.00 MHz USB.
  5. Pushing the A/B function button, you can have different audio signals, if that 36 MHz reference oscillator is miwadjusted.
  6. Using a small flat bladed scredriver, adjust trimmer capacitor TC1, near connector 8 of the PLL Unit (the location shown in Instruction Manual in the same section as above) until those audio frequencies from VFO's A and B are equal.
  7. Disconnect the calibration cable and reassemble the radio. This procedure can be done by ear with good accuracy without any measuring equipment. WWV is too weak here in Finland to use it as comparative signal for the procedured described in "Instruction Manual", Section 5-8-3.

B>Connection of the KENWOOD TS440S to a DATA

Connection of the KENWOOD TS440S to a DATA terminal such as a Kantronics KAM using the rear ACC2 13 pin jack.

                   ____ 4    3    2    1
       GROUND ___ |
                  |____ 8    7    6    5
                  |___ 12   11   10    9____________
                           /                        |
       MIC    ____________/    13                   |
                                |                   |
                                |                   |
                               \_/                 \_/
                              =====               =====
                                |                   |


       Pins        |           Application

        3              Data output - not used as the level is very low
                       the prefered connection is via the speaker output
                       this also allows fine adjustment of level to
                       enable best decoding. (A switch on the speaker to
                       'mute' it when required is a good idea.)

        4              Ground - you may have to experiment with these
        8              connections to eliminate RF feedback and noise.
       12              Here they are all strapped.

        9              Mic mute - prevents audio pickup from the mic when
                       earthed. By connecting to the PTT line as shown
                       through a diode automatically MUTES the mic when
                       using data. When the front panel PTT or MIC PTT
                       are used the microphone is 'live'.

      13               Standby - PTT which when taken to ground puts the set
                       'on air'. By connecting through a diode as shown
                       doesn't affect the PTT operation but allows auto
                       mic muting.
The diodes used can be virtually anything, here they are IN4148.

The INPUT audio to pin 11 must be quite a high level. If using a KAM you are certainly going to have to change the HF LEVEL JUMPER in the KAM. The level of the KAM as shipped suites connection to the FRONT PANEL MIC but not the rear connector, you can however correct this with the jumper. People using the PK232 have complained of NO TX AUDIO, I suspect the level is so low that only local minitoring will show a level present.
Kenwood Computer Interface Instructions

These Instructions are TS-440 specific, but the basics also apply to the TS-940, TS-811 and TS-711.

It is possible to save yourself a few dollars and lose nothing in quality by buying the parts to upgrade your Kenwood radio for computer control. Just purchase the parts were you find them and install them using the instructions in the Radio's Manual.

     IC 54 is a uPD-8251-AC   Serial Communications Interface.
                Commonly called an 8251A    ($1.89 Mail Order)
     IC 55 is a TC-4040-BP    12 Stage CMOS Divider.
                Commonly called a 4040      ($0.69 Mail Order)
The IC-10 Interface Kit from Kenwood Contains ONLY these two parts and less instructions than are in this file. The only thing you are going to miss, is the $22+ price tag on the IC-10 Kit.

 Signals are    TTL levels  (NOT RS-232)
Baud rate is    4800 (1200 Opt.)
   Format is    ASCII Serial;  1 Start, 8 Data, 2 Stops
The Baud rate may be changed to 1200 Baud by removing jumper W50 and installing a jumper from the left pad to the center pad as viewed from the front of the radio. This will become obvious once you have the radio opened up. Many other Baud rates are possible, just look at the schematic.

As long as you are in the radio, lift D-60 to enable the 10 Hz. display. The main tuning knob is varing this digit, so you might as well see it. It also helps when using RIT/XIT as the RIT/XIT display does not resolve the 0.01 KHz. digit. This Modification is in the Radio's Book.

Not in the book is the fact that if you lift D-80 and do an MPU reset, you will be able to transmit on any frequency between 1.5 and 30.0 MHz. This means you will be able to work the Mars nets, Etc. Do not transmit out of band. It is illegal even if it is accidental.

Some computers use TTL levels on their serial ports. If so, here is a time when you will not have to convert it to RS-232.
The IF-232 Interface from Kenwood is a 1488 and a 1489 chip in a box. These are an RS-232 Quad Line Driver and Receiver and are available at Radio Shack for $1.29 Each. Here is an easy project that will save you a lot over the $69+ Kenwood price of the IF-232 Interface. The 1488 needs a + and - supply.
Unregulated + and - 12vdc is just fine. Get the +5 vdc for the 1489 by putting a 7805 regulator on the +12 vdc supply. 100 mA.
is about the max you'll draw, so the smallest transformer you can find will still be plenty large. Don't forget to series up two of each gate to cancel the inversion that the 1480's produce.

ACC-1  Connector                  Use a 6 Pin DIN Connector.
                                         (Radio Shack $1.29)
Pin     Signal  Comments

1       Gnd     Signal Ground
2       TXD     Serial Data from Radio to Computer
3       RXD     Serial Data from Computer to Radio
4       CTS     Computer Ready;  (Radio Input)
5       RTS     Radio Ready;    (Radio Output)
6               No Connection

Pins 4 and 5 may be left Unconnected.

***** Command Description for Kenwood Computer Interface *****

                Auto Information
                The Radio Will Send the Status Info Automatically
                Whenever the Operator Manually Varies any Function
                on the Radio which is Covered in the IF; Command
                        Where   n = 0 for Auto Info OFF
                                    1 for Auto Info On

                The Status Information Will be Sent in the Form :
                        As defined in the IF; Command

                Display Memory
                This is a Factory Diagnostic Function
                and is of no practical use to the operator

                The Contents of the MPU Memory will be Read
                        Where   nnnn = MPU Address (0000 Thru FFFF (HEX))

                The Contents of the MPU Memory Will be Sent in the Form :
                        Where   nnnn = MPU Address (0000 Thru FFFF (HEX))
                              aa~~kk = Hex Number Pairs Of Next 16 Locations

                The Frequency or Memory Channel
                Will Decrement One Step

                Frequency VFO A / VFO B Request
                The Frequency in the Selected VFO Will be Read

                The Frequency Will be Sent in the Form:
                 FAggmmmkkkhhh;   or
                        Where    gg = GHz. Value
                                mmm = MHz. Value
                                kkk = kHz. Value
                                hhh =  Hz. Value

                Frequency VFO A / VFO B Select
                The VFO Selected Will be Set to the Frequency Defined
                        Where    gg = GHz. Value (May be sent As 00 or Spaces)
                                mmm = MHz. Value
                                kkk = kHz. Value
                                hhh =  Hz. Value

                Function Select
                The Function Defined Will be Selected
                        Where   n = 0 for VFO A
                                    1 for VFO B
                                    2 for MEMORY

                Identify Model Request
                The Model of the Radio Will be sent in the Form :
                        Where : n = 1 for a TS-940 (*)
                                n = 2 for a TS-811 (*)
                                n = 3 for a TS-711 (*)
                                n = 4 for a TS-440

                Read Information Request
                The Status Information Will be Sent in the Form :
                 IFggmmmkkkhhh     snnnzrx yytdfcp
                        Where   gg~~hhh = Value as defined in FA Command
                                      s = "+" or "-" Value of RIT/XIT
                                    nnn = Value of RIT/XIT (n.nn kHz.)
                                      z = "0"  (Not Used in TS-440)
                                      r = Value as defined in RT Command
                                      x = Value as defined in XT Command
                                     yy = Memory Channel No.
                                      t = 0 for Receive
                                          1 for Transmit
                                      d = Value as defined in MD Command
                                      f = Value as defined in FN Command  
                                      c = Value as defined in SC Command
                                      p = Value as defined in SP Command  

                Lock Knob
                The Manual Frequency Control Functions Will be Disabled
                        Where   n = 0 for Lock OFF
                                    1 for Lock ON

                Memory Channel Select
                The Memory Channel Defined Will be Selected
                        Where:  x = Don't Care   (Use "0" or Space)
                               mm = Memory Channel No. (00 thru 99)

                Mode Select
                The Mode Defined Will Be Selected
                        Where:  n = 1 for LSB
                                    2 for USB
                                    3 for CW
                                    4 for FM
                                    5 for AM
                                    6 for FSK

                Memory Read
                The Memory Channel Defined Will be Read
                        Where:  n = 0 for RX VFO
                                    1 FOR TX VFO (Split Channels Only)
                                x = Don't Care      (Use "0" or Space)
                               rr = Memory Channel No.    (00 thru 99)

                The Memory Information will be sent in the Form :
                 MRn rrggmmmkkkhhhdz    ;
                        Where:  n = 0 for RX VFO
                                    1 FOR TX VFO (Split Channels Only)
                               rr = Memory Channel No.    (00 thru 99)
                         gg~~hhh = Value as defined in FA Command
                                d = Value as defined in MD Command
                                z = "0"  (Not Used in TS-440)
                        (Note: Four trailing Spaces)

                Memory Write           
                The Memory Selected Will be Set to the Frequency Defined
                        Where:  n = 0 for RX VFO
                                    1 for TX VFO (Split Channels Only)
                                x = Don't Care  (Use "0" or Space)
                               rr = Memory Channel No.    (00 thru 99)
                          gg~~hhh = Value as defined in FA Command
                                d = Value as defined in MD Command
                                z = "0" (Not Used in TS-440)

                RIT/XIT Clear
                The RIT/XIT will be set to 0.00 kHz.

                RIT/XIT Down
                The RIT/XIT will Decrement by 0.01 KHz. (10 Hz.)

                RIT/XIT UP
                The RIT/XIT will Increment by 0.01 KHz. (10 Hz.)

TS-440S increase the power by ALC control

This article also tells how to increase the power of the TS-440 by adjusting the internal ALC control. The procedure is applicable to other rigs.

Illustration captions:
  1. Remove 17 screws holding on the bottom and top covers. The bottom cover comes off, and the top cover is carefully removed and put next to the radio. It is till connected via the speaker wire.
  2. Gain access to the front of the unit by removing two top side screws and loosening two bottom side screws. This allows the front assembly to swing open.
  3. Remove the shiny silver control board protection plate. This requires removing two screws on the top and three screws on the bottom. Lift the plate out completely. Locate diode D-80 in the bottom left-hand corner. Snip it for all-band transmit.
  4. Now locate D-66 and snip. It adds 10 Hertz readout to your digital frequency display.
  5. Carefully reassemble the control plate using a magnetized tiny screwdriver to hold the five tiny screws in place. Don't pinch any wires. Also, close up the front and replace the top and bottom covers with 17 screws.
  6. Connect power. Depress A=B switch and turn on the power simultaneously. This resets the microprocessor for all-band transmit and 10 Hz frequency display.

TS-440 with PIN-Diods

Hallo, ts440-owners!

Recently i read about an upgrade for the ts440 concerning the bandswitc-diods.
Originally, there are simple switching types built in. For better high level performance i decided to replace D2,3,4,5,6,7,...23,68 by the ECG553 PIN Diode.
The result was not so doubtless positive. i could not really confirm an advantage. unfortunately, i have no measuring equipment for determining the intercept point.
But on 40m , where i sometimes have problems using a 160/80/40/30/20m 5-band fullsize dipole, i still suffer intermodulation effects.
I can not really say, if it is much better after the replacement, but i'm sure, it isn't worse (hi).
Some remarkable progress was the usage of the built-in tuner in the receiving pass. that really helped espacially on the 10mc band to overcome the problems of interference.
But best results and a final solution i found in using an external preselector as described in the cq-dl several times.
That really did it! Of course you need to add on to cinch connectors at the rear panel.
It is no real problem.
so, my advice:
dodn't modificate the diods or use of the tuner for reception.
The result is too poor compared with that of an external preselector.
TS-440S operation with the MC-85

With some TS-440S transceivers, insufficient modulation may occur when the MC-85 compression switch is turned on. This may be caused by too much of a voltage drop across resistor R172 on the IF unit of the transceiver . If this is found to be the case, change the resistor from 1K ohm to 100 ohms.

Required part

100 Ohm, 1/6 Watt resistor.......RD14CB2C101J

  1. Disconnect the power supply and antenna from the transceiver.
  2. Using a #2 Phillips screw driver, remove the 9 screws from the top cover of the transceiver. Remove the cover and unplug the speaker wire.
  3. Locate resistor R172 on the component side of the IF board (Figure 1).
  4. Using a #1 Phillips screw driver, remove the 7 screws that secure the IF unit to the chassis of the transceiver.
  5. Pull the board up and rotate it towards the front of the transceiver to expose the foil side of the board.
  6. Desolder and remove resistor R172 from the board.
  7. Install and solder the 100 ohm resistor in place of R172.
  8. Assemble the transceiver by reversing steps 1 - 5.
This modification may be covered under warranty.
Time required for this modification is 0.5 hrs or less.
TS-440S notch filter low frequency improvements

The low frequency attenuation characteristics of the notch filter can be improved by reducing the input level to the notch filter chip (IC1). To compensate for the loss of input level, the amount of negative feedback to the audio amplifier (IC7) will need to be reduced. This modification is already incorporated in all models beginning with serial number 704XXXX.

Required parts:

120K Ohm, 1/6 Watt resistor ........ RD14CB2C124J
390 Ohm, 1/6 Watt resistor ........ RD14CB2C391J

  1. Disconnect the power supply and antenna.
  2. Using a #2 Phillips screw driver, remove the 9 screws from the top cover. Remove the top cover from the transceiver and unplug the speaker wire.
  3. Locate resistors R86 and R229 on the component side of the IF board (Figure 1).
  4. Using a #1 Phillips screw driver, remove the 7 screws that secure the IF unit to the chassis of the transceiver.
  5. Pull the board up and rotate it towards the front of the transceiver to expose the foil side of the board.
  6. Desolder and remove both resistors from the board.
  7. Install and solder a 102K ohm resistor in place of R86.
  8. Install and solder a 390 ohm resistor in place of R229.
  9. Assemble the transceiver by reversing steps 1 - 5.
This is an optional change that may not be performed under warranty.
Time required for this modification is 0.5 hrs or less.
TS-440S protecting Q33

If pin 7 (RL) of the remote connector is accidently connected to ground, current from the 14 volt line (14L) will damage transistor Q33 on the IF unit. This will prevent the radio from transmitting. To protect Q33, a 4.7 ohm resistor should be installed in series with the RL line on the foil side of the IF board. In the event that pin 7 is connected to ground, the resistor will open, but the transceiver will still be capable of transmitting.

Required part:

4.7 Ohm, 1/6 Watt resistor ........ RD14CB2C4R7J

  1. Disconnect the power supply and antenna from the transceiver.
  2. Using a #2 Phillips screw driver, remove the 9 screws from the top cover of the transceiver. Remove the cover and unplug the speaker wire.
  3. Locate connector 19 on the IF unit.
  4. Using a #1 Phillips screw driver, remove the 7 screws that secure the IF unit to the chassis of the transceiver.
  5. Pull the board up and rotate it towards the front of the transceiver to expose the foil side of the board.
  6. On the foil side of the board, locate the trace that is connected to pin 3 (brown wire) of connector 19.
  7. Using a craft knife, cut the trace comming from pin three so as to open the foil trace.
  8. Solder the 4.7 ohm resistor across the now open trace (i.e. in series with the trace).
  9. Assemble the transceiver by reversing steps 1 - 5.
This is an optional change that may not be covered under warranty.
Time required for this modification is 0.5 hrs or less.
TS-440S Case Screws binding in the heat sink

Kenwood U.S.A.
Service Bulletin Extract
Amateur Radio
Number: SB950
Date: 01/20/89

Occassionally a case screw that fastens to the heat sink of the TS-440S will cross thread or bind when it is being inserted or removed. Binding may be caused by tooling marks on the screw or by burrs on the tapped threads in the heat sink. When a screw starts to bind, DO NOT TRY TO FORCE IT! as this may cause the head to shear off. If the screw is being removed and it starts to bind, return the transceiver to KENWOOD. Do not make attempts to remove the screw. In addition, if a transceiver is being brought to you with a scrw sheared off, return the unit to KENWOOD. Do not attempt to drill out the screw.

If a screw starts to bind when it is being installed, carefully back it out. Inspect the screw for marks or burrs and replace it if it is questionable. Since the threads in the heat sink may be causing the screw to bind, they should be cleaned by running a 3 x 0.5 mm tap into each hole.
The tap is inexpensive and can be obtained at may of the larger hardware stores.

To avoid cross threading, make sure the covers are properly aligned when they are being installed. Proper alignment means that there is a clear path for the screw to turn into the heat sink.
This assures that the screw does not rub against the case and result in it turning into the heat sink at an angle.
TS-440 RX Audio Mods

Here's some easy modifications to improve the rx audio fidelity of Kenwood TS-440's. All references below are to the IF board component designations.
And, of course, I take no responsibilty for anything you do to your radio. Be careful. The IF board on the 440' is about the easiest one to get at.

TS-440S SSB Power-adjustment

From: [email protected]#OVL.NLD.EU

Hello TS 440 user..

The last few weeks I've seen questions of how to make the power in SSB mode for the TS440S adjustable without changing the Mic-Gain. It's a very easy job to do.

Take off the top cover of the rig.
At that moment you have a sight on the first unit (IF-Unit)
Than you have to look for Diode 49.
You will find Diode 49 at about 5 CM from the backend of the unit and about 6,5 CM from the leftside of the unit.
Just next of C138 and between plug 38? (red/orange wires) and plug 26 (black-cover/blank wires) Just cut that Diode 49,bend one part a little away and leave the part's where they are. It's the best way to do I think.
Replace the topcover.
From now on it is possible to adjust only the power in SSB mode by just turning the CARRIER Control at the front of your rig and leave the Mic-gain for where it is.
Turning counterclock will minimize the power until a 20mW or something like that.
Because most TS440 users have'nt used their carrier control that much I think it's better to pull off the MIC/CAR knobs and spray some contact cleaner in the shafts. (I know,it's not the best way).
When you switch your rig into the CW mode you can adjust the power in what you like,switch the mode in to USB or LSB and if it is correct the power will not come above the level that what you have adjusted in the CW mode.
Just simple , is'nt it?
Of course you will do this all in your own responsibility because I won't take any!!! Agree?

Go Back To The Kenwood Mods Page

Go Back To The Main Modifications Page

Go Back To The CB / HAM Radio Main Page

Go Back To The Main Home Page

Copyright © The Defpom 1999