Modifications for the ICOM - RogerK

| IC31 uPD4094BG || |1 2 3 4 |5 6 7 8 | oo | +B8-/| || | L| +---------(pin13 ic31)------B8W-----o 3| o 0| || 8 7 6 5 4 3 2 1| | || | IC32 uPD4094BG || | |+------------------- 9 10 11 12 13 14 15 16|---L8------+3. Above pin 1 you will see two vias. The first via is connected to pin 1, and the second connects to a horizontal trace comingfrom the left. This trace is B8W and goes to the emitter of the PNP Q38 transistor. Cut the trace just before the via.--- alternative not recommended ---2. Remove the shield from the top of the board. There are 30-40 solder points from the shield to the board.3. Under the board on the top of the board, remove R-353 and Q-38. They are located to the left of the IC-36 chip on the topof the board under the shield.--- alternative ends ---4. On the underside of the board, Locate IC-32. There are two IC chips. IC-32 will be just down and to the right of the shield.5. Using a pointer, point at the left upper pin, and go toward the top of the board. You will find a trace that stops. It comesout from under IC-31, pin 14, and stops. It should be the sixth trace up from the top of the Chip. This signal activates theVHF preamp.6. Using a Xacto knife, (or something similar) Cut the trace in the bend halfway between IC-31 and the solder point (via).7. Make a jumper wire, and jump the connection, from Pin 11 of IC-32 to the newly isolated trace. Alternative: solder the wirefrom the via at pin 1 (bottom left pin) of IC31 and the newly isolated via.8. Reassemble the radio.Transmit from 200 kHz to 200 MHz continuous (works from 1 MHz, Tx HPF)ICOM does not warranty these mods.Parts of this text are from: test at your own risk, have fun and 73 de OE1GQA Guenter - ViennaExpanded VHF part 2The VHF IC38 TA4001F 12.5dB preamp has a bandpass input filter from 140 to 150 MHz. If you try to transmit outside of thisband you will either transmit nothing or spurious. (e.g. tx=70 MHz lo=140 MHz). See plottxold.pdf.The four pin IC38 is located on the underside of the main board, just on the right of IC31. (cutout hole top left)3*2o *o 4*1-ino |o C330 C329o L99 LIC31 o C333 C331 1L100 0C332 1C334Note: L101 is ommitted in the schematic of the service manual. It connects at C334 and goes to ground.