Modifications for the ICOM - RogerK

3. Remove the six screws holding down the Main Unit PCB.(Or is that seven??? I have a habit of losing the damn things!)4. Disconnect the coaxial lead plugged into J2 on the right hand side of the Main Unit PCB.5. Disconnect the internal speaker feed to J17, located at the rear right hand side of the PCB, next to the external speakerjack.Disconnecting these two feeds will make it easier to turn the PCB over to gain access to the solder-side.6. Carefully pry the PCB loose. The "Ext Sp" and "Key" jacks on the back of the PCB make this quite awkward.The PCB will need to move towards the front of the radio in order to clear the rear panel.7. When it's in the clear, the rear side of the PCB can now be flipped over.8. Remove C279 (0.0047uF). This is located front left - see picture 2.9. Remove the link near C279 designated as W159.10. De-solder the other nearby holes associated with the filter.(These holes will be immediately obvious if you have a look at the pin-out of the filter).Picture 2 - Location of filter area on Main Unit PBA11. Solder the CFJ455K5 filter in position.12. Re-orientate the PCB back to its normal position.13. The blue wire going to the PCB just near J10 needs to be cut, preferably as close to the pin as possible.J10 is located front left of the PCB, near where the filter was just installed.You will find this much easier to do if you temporarily remove the connector plugged into J10.This blue wire is the "PBTV" line, the Pass Band Tuning Volts line, and was fixed to +4 volts, ie; set for the centre of the"normal" passband.Now there are a number of ways of providing this line with the adjustable 0 - 8 volts that is required.I shall now describe the method I used - using the (waste of space) "Data Level" control.14. Disconnect the connector that goes to J20. This is the feed that goes off to the "Data Level" pot. Put this aside for now.15. De-solder and remove J20 from the PCB.16. In J20s place I mounted a vertical 10kohm trimpot - see picture 3.