Modifications for the ICOM - RogerK

1. Remove the covers to gain access to the main circuit board.2. Remove R354 (22K) from the main circuit board and replace it with a 10K (ICOM P/N 915-01113) resistor.3. Re-install the main circuit board and replace the covers on the radio.This modification is read 702 times.top of page19-07-1998(IC-275) Prevent PLL unlock at high ambient temperature1. Change the following parts on the PLL boardOriginal NewPart Value ValueC101 12 pf 50V CH 6 pf 50V CHR137 35D 45 SN (ICOM P/N 915-04229)R133 22K 15KC191 3 pf 50V 6 pf 50V2. The thermister should be installed in series with R133. Unsolder one end of R133 and solder R137 in series with it.This modification is read 676 times.top of page19-07-1998(IC-275) Improve voice synthesizer and side tone audio1. Remove C214 (.47 uf capacitor) from the main board.2. Install a .1 mf 16V barrier layer capacitor in series with a 2.2 K 1/8W resistor from the emitter of Q58 and the base of Q59on the foil side of the board.This modification is read 662 times.top of page19-07-1998(IC-275) Prevention of PLL unlock at 174 MHz1. Remove and replace the following components on the PLL BoardOriginal NewPart Value ValueR130 120 Ohm 270 OhmR131 47 Ohm 18 OhmR132 120 Ohm 270 OhmC42 60 pf 50V 30 pf 50VC47 43 pf 50V 62 pf 50VThis modification is read 701 times.top of page