FT-290R2 FT-690R3 FT-790R2 ---- 9600 Kbd --------------------------------------------------------------------------- 1. Remove the two side brackets and the top and bottom covers of the rig. The speaker is attached with a small plug-in connector, which is easily removed. 2. The radio has two PCBs in the main body of the set, and two smaller ones as part of the front panel assembly, one behind the other. Turn the radio over to look at the bottom PCB. Identify the FM discriminator IC near the centre of the board, with the number MC3357P. The receive audio for 9600 Bd comes from pin 9 of this IC, which is diagonally opposite the dot on top of the IC marking pin 1. I carefully soldered the wire directly to the IC pin. Don't cook the device!! 3. Turn the radio back upright and look at the top PCB. On the FT290R2/690R2, with the front facing you, just to the right of centre, find C117, an electrolytic capacitor, which is next to trimming coil T13. In the FT790R2, this is C114 and T13. This bit is not easy, but the wire for transmit audio on 9k6 has to attach to the negative lead from C117/114. I managed to do it on the top side of the board, as it was not installed too close to the surface of the PCB. It may be necessary to disassemble the rig to the point where you can get at the underside of this PCB and attach the tap there. If so, be careful to remember where all the plug-in connecting leads go, as you will need to disconnect most of them to get the front panel assembly separated from the main body. C117/114 and T13 feed into the varactor diode D16/D14, which is a surface mount component on the underside of the PCB. Attaching the tap directly to the diode did not work in my case, I assume the impedances here are quite important and C117/114 provided the right match. 4. I add this next bit as an idea. On the top PCB, over near the right hand side, near the push rod for the panel light switch, there are two plug-in connecting leads. The one slightly nearer the centre of the rig has a white, black and brown wire coming from it. The brown wire here takes audio to the speaker pin, pin 4, of the front panel mic jack. I cut this wire at the plug-in connector, fed it through to the underside PCB, and connected this to pin 9 of the MC3357P. Now the audio to pin 4 of the front panel jack is 9k6 friendly. If the squelch threshold on your rig is severely affected by this, replace the brown wire with shielded audio wire and earth the shield to the chassis. I had to do this on the 290R2, and the radio needs to be disassembled to get in behind the front panel connector to the other end of the brown wire. Attach the shield in the same place as the small capacitors which come from several pins on the front panel jack. This is right next to the other end of the brown wire. 5. At the same time, while the rig was disassembled, I soldered the other end of the transmit audio wire (from C117/114) to Pin 5 of the front panel mic jack. This pin normally is not connected to anything, but is soldered to the front panel PCB for strength. Again, attach the shield at the same place as before, which is right nearby. Doing this, I can wire up a lead for 1200 Bd packet using Pin 8 for transmit audio (the normal Mic pin) and a lead for 9600 Bd packet using Pin 5 instead. Connecting the microphone still works no worries for normal voice QSOs. I don't use a speaker mic on my rig, the audio from this may sound a bit "tinnier" after the mod, but it shouldn't be too bad. Connecting things up this way also keeps the rig looking exactly as it did before - no extra wires or plugs coming out from inside the set. I recommend using shielded audio wire for both transmit and receive connections inside the set, to avoid feedback, RFI, desensing and so on. This would not be the only way to connect it up though. 6. When all done, reassemble the rig. Be careful the black push rod for the light goes through the hole in the rear panel correctly before pushing the front panel back onto the main body, as you may break the little switch. Check none of the leads are pinched anywhere as the bits go back together. Also remember to reconnect the speaker before replacing the top cover. You may also find you need to experiment with the transmit audio level being supplied to the rig from the TNC, to get the right deviation. The KPC9612 has a trimpot inside for doing this, as would most other TNCs or modems I expect. ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ» º KB2LJJ BBS RADIO MODS BATABASE º All the MODS are captured by packet. ÈÍÍÍÍÍÍÍÍÍÍÍ» ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ This BBS takes no responsability or ÉÍÍÍÍÍÍÍÍÍÍͼ ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ» liability for any damege resulting º KB2LJJ @ KB2LJJ.NJ.USA.NA º from any modification. ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ 73s John kb2ljj SySoP