Modifications for the ICOM - RogerK

19-07-1998(IC-735) IC-735 Remote WorkingI have finally got the remote control working on the IC735.The interface is home-made and uses just 2 transistors, 1 diode, 5 resistors, DB25 and a DB15(to get 5v from games port).The software is a major re-hash of VK7TM's FT757 effort in ARA.All functions are driven from the XT keyboard and the software allows scanning of a LARGE number of frequencies on the sameor on different bands.The trials and tribulations of all this effort were NOT assisted in any way by the manufacturers local office in Melbourne. A call forinformation was not very successful. (try it and see!)If you are contemplating the idea of turning your IC735 into a multi-channel HF scanner, I may be contacted @ VK3YZW BBS..The software is suitable for use with XT/AT Clone...Available control functions:Send a new frequency to the radio from the keyboard.Send a new Mode to the radio.Select VFO A or VFO B.Select a different memory channelEnable the selected memory channelWrite current Freq/Mode to selected memory channel.Write current Freq/Mode to last used VFO.Read/Edit/Use a frequency file from Disk.SCAN frequencies in a frequency file.The frequency files contain frequency/mode/description of station all of which is displayed on the screen when the file is active.This modification is read 1680 times.top of page19-07-1998(IC-735) ICOM Radio/RS232 interface which meets RS232 specificationsThis circuit has no expressed or implied warranty of any kind.It works very well for my IC-735 and with three different computers.It has not been used on any other Icom radio but should be compatiblewith a number of other desktop models.BUT!! USE IT AT YOUR OWN RISK !D. W. Bray, K2LMG -- Clarkson UniversityThis design uses a chip designed to produce both the + and - voltages required by RS232 from a single +5 volts, andincorporates two receiving and transmitting inverters which meet the RS232 specifications. The only other chip needed is abuffer which allows its output to be driven from another source.A circuit drawing is presented below. In words, the implementation is:ICL232 ChipPin 14 is output to RS232 Pin 3; Pin 13 is input from RS232 Pin 2; Pin 11 is tied to 7417 Pin 2 and to a 270 ohm resistor, theother resistor connection is tied to +5V; Pin 12 is tied to 7417 Pin 3.ICL232 ChipCapacitors. C3 + lead is tied to Pin 2, C3 - lead is tied to +5V; C1 + lead is tied to Pin 1, C1 - lead to Pin 3; C2 + lead is tied toPin 4, C2 - lead tied to Pin 5; C4 + lead tied to GND, and C4 - lead tied to Pin 6.ICL232 ChipVCC is Pin 16 which is tied to +5V. GND Pin is 15 which is tied to ground. All leads not mentioned should be open.7417 ChipPins 2 and 3 are tied as discussed above. Pins 1 and 4 are connected together and to the center pin of a 1/8" plug for connectionto an Icom radio.7417 Chip VCC is Pin 14 which is tied to +5V. GND is Pin 7 which is tied to ground. All leads not mentioned should be open.The ICL232 chip uses an internal oscillator to create the +- voltages by voltage doublers (which require C1 and C2). Pin 2 is a+10V source, Pin 6 is a -10V source (but are not connect to anything is this design). The Transmitters (Tx) and Receivers (Rx)meet RS232 specifications. One source of the ICL232 is: DigiKey Corp., Thief River Falls, MN 56701-0677 -- 1-800-344-4539.Price approximately $4.80.The 7417 is an open collector buffer chip. This allows a buffer output to be driven from another source, and is compatible withthe Icom IC-735 internal pull-up circuit. Designs which use 1488/1489 chips, where the Icom input/output lead is tied to a buffer