Modifications for the ICOM - RogerK

23-11-2001(MISC) QRP mod for ICOM transceivers/9-volt - o-------/ ------/////---------alkaline S1 R1 |battery + o-- || >| < shielded cable_____ variable R2--> > ALC--- < ------------------> JACK- > | || | ground | ON|__|| RADIO| |__________--- ---- -With this circuit connected to the radio, the power output is adjustable between 0 ---> 100W. For best results. leave the RFpower control at maximum and adjust for desired power using R2.S1 is used to turn off circuit when radio is not in use or QRP operation is not desired.Radio Model: R1 value R2 valueIC-761, 765 47K 20KIC-720(A), 735, 740, 745, 751(A), 275A/H 2M 1MIC-725, 726, 728, 729, 736, 737(A) 220K 100K06/01/94 CJRFor the IC-820H use the values for the IC-761, 765. The IC-781, IC-765 and the IC-820H all have the same ALC characteristics:Control voltage : -4 to 0 voltsInput impedance : More than 10 K ohmsThis modification is read 898 times.top of page16-04-2001(PS85) ICOM PS85 fan modificationAuthor: Mark - pe3hmp@hotmail.com.MODIFICATION.NETWhen I bought the icom PS85 power supply one thing inmediatly catched my attention, THE NOISY FAN.You would expect if You pay $450 usdollar (in the Netherlands) that this would be a great power supply and not a noisy one !Well after 2 day I decided that it was time to do someting about it, after contacting icom I heard that there was no mod. for it soI had to do it myselve.This mod is using a NTC to sense the temp and control the speed of the fan so the temp wil not exeed 50 degrees celcius.Potentiometer P is used to adjust the lowest speed of the fan (I set P so that the fan gets at least 6,5V at 20 degrees celcius)