Various Kenwood TS-440S Modification notes: =========================================== CW sidetone improvement ----------------------- Under certain circumstances, the CW side-tone frequency is unstable while transmitting and rises. This is due to RF entering the side-tone oscillator via the keyer cable. Better blocking will sharply recude the effect. Required part: 10nF ceramic capacitor 1. Disconnect power supply and antenna from the transceiver. 2. Using a #2 Philips screw driver, remove the 9 screws from the top cover. Remove the top cover from the transceiver and unplug the speaker wire. 3. Locate the small SMD board (X59-1060-00) which comprises the CW side-tone oscillator on the component side of the IF board. 4. Using a #1 Philips 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. Install and solder a 10nF ceramic capacitor between pin 9 of the SMD side-tone oscillator board (X59-1060-00) and ground. 7. Reassemble the transceiver by reversing step 1 to 5. Time required for this modification is 0.5 hour or less. Protecting Q33 -------------- If pin 7 (RL) of the remote connector is accidentally grounded, 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 power supply and antenna from the transceiver. 2. Using a #2 Philips screw driver, remove the 9 screws from the top cover. Remove the top cover from the transceiver and unplug the speaker wire. 3. Locate connector 19 on the IF unit. 4. Using a #1 Philips 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 coming 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. Reassemble the transceiver by reversing steps 1 to 5. Time required for the modification is 0.5 hours or less. FM rx-modification ------------------ The TS-440 FM receiver seems to be constructed for 25kHz steps. Using 10kHz steps, the bandwidth is much too wide. I changed the 455kHz Murata F-Type filter into a narrow H-Type, and thought it was successful, but strong signals on adjacent frequencies now muted my speaker. Using the 8.83 MHz filter on the RF board, which is normally bypassed by FM solved this problem and I got a very useful FM rig, even with the original F-Type filter. Required parts: 2 diodes 1N4148 1. Disconnect the power supply and antenna from the transceiver. 2. Using a #2 Philips screw driver, remove the screws from the bottom cover. Remove the bottom cover from the transceiver. 3. Locate resistor R59 and capacitor C131 on the component side of the RF board. 4. Using a #1 Philips screwdriver, remove the screws that secure the RF unit to the chassis of the transceiver. 5. Remove all plugs still keeping the board in position. 6. Pull the board up and rotate it towards the front of the transceiver to expose the foil side of the board. 7. Find the junction of R59 and C131 opposite their ground connection. 8. Disconnect R59 from C131 by scratching the track with a sharp knife. 9. Install and solder diode A with anode connected to R59 and cathode connected to C131. 10. Install and solder diode B with anode connected to R58/C131 and cathode connected to C131. 11. Remove resistor R57. 12. Reassemble the transceiver by reversing the steps 1 to 6. Using the antenna tuner for TX and RX ------------------------------------- Remove the case from rig. Remove the (4) screws that hold the antenna tuner in place. Slide antenna tuner out to get to the coax connections. Remove the "in" coax attached to antenna tuner from FO connector on the 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 on 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 connect shield to ground. Solder other half of coax to antenna connector, and connect shield to ground, and plug other end into "out" connector of antenna-tuner. Connection of the TS-440 to a DATA terminal such as Kantronics KAM using the rear ACC2 13 pin jack. ---------------------------------------------------- ____ 4 3 2 1 GROUND ____| |____ 8 7 6 5 | |___ 12 11 10 9____________ / | MIC _______________/ 13 | | | | | \_/ \_/ ===== ===== | | |___________________| | | | PTT Pins Application ----------------- 3 Data output - not used as the level is very low. The preferred 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 connections to 8 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 it 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 taked to ground puts the set 'on air'. By connecting through a diode as shown it doesn't affect the PTT operation but allows auto mic muting. The diodes used can be virtually anything, here they are 1N4148. 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 suits 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 monitoring will show a level present.