Modifications for the ICOM - RogerK

19-07-1998(IC-3200) Fix for IC-3200A used on packetFor those poor souls who are trying to use the ic-3200a on packet here is here is some relief.The problem is that when going from transmit to receive there is a delay in the receive audio turn on, which is on the order of500 milliseconds and may be too long for some packet situations unless everyone had their txdelay set to 750 milliseconds.There are two ways to resolve the problem. Both are fairley simple. the easiest way is to remove the muting on the audio P.A.I.C.The instructions follow:1. Remove the cover that has the speaker attached to it (being careful of the wires)2. With T2. with the front of the radio facing you, look for the audio P.A. I.C. In audio P.A. I.C. in the right rear part of theradio next to the chassis it is marked "upc2002", looks like a to-220 case transistor, and has five leads on it3. Immediately to the left of the "upc2002" is a diode standing on end, and marked "D19" on the circuit board this is the diodethat mutes the audio P.A. I.C. during transmit4. Cut one leg of "D19" and the audio P.A. I.C. will no longer be muted during transm ithis is all that is required and my testshaveShown that the ic-3200a will work with other tnc's with txdelay's set as short as 150 milliseconds where before this modificationa txdelay of about 600 milliseconds was required of the station trying to communicate to the IC-3200A.This modification is read 665 times.top of page19-07-1998(IC-3200) IC-3200A TX to RX delay fixFor those poor souls who are trying to use the ic-3200a on packet here is here is some relief.The problem is that when going from transmit to receive there is a delay in the receive audio turn on, which is on the order of500 milliseconds and may be too long for some packet situations unless everyone had their txdelay set to 750 milliseconds.There are two ways to resolve the problem. both are fairley simple. the easiest way is to remove the muting on the audio P.A.I.C.The instructions follow:1. Remove the cover that has the speaker attached to it (being careful of the wires)2. WIth the front of the radio facing you, look for the audio P.A. I.C. In the right rear part of the radio next to the chassis it ismarked "UPC2002", looks like a TO-220 case transistor, and has five leads on it3. Immediately to the left of the "UPC2002" is a diode standing on end, and marked "D19" on the circuit board this is thediode that mutes the audio P.A. I.C. during transmit4. Cut one leg of "D19" and the audio P.A. I.C. will no longer be muted during transmit and the receiver will respond almostimmediately.This is all that is req'd and my tests have shown that the IC-3200A will work with other tnc's with txdelay's set as short as 150msecs where before this modification a txdelay of about 600 msecs was required of the station trying to communicate to the IC-3200A.For those interested in an alternate method here is what has been done by WB4FOW on several other radios:Since about 1985 most icom radios have pin 8 of the microphone connector wired to the speaker. This is convenient for thewiring of a tnc and is usually easy to modify so that receive audio is taken from the high side of the volume control.To get back to the subject of the alternate modification for the IC-3200A, you can rewire pin 8 of the microphone connector tothe high side of the volume control and avoid the muting circuit but if you plan to leave the tnc wired permenantly to the radioand also,to use the radio on voice you will need to change a resistor in the tnc so as not to load down the audio at the volumecontrol. the value of this resistor will have to be determined experimentaly.If anyone requires more information or assistance with this matter feel free to call clark, wb4fow, at 305-594-4313 mondaythrough friday 10am to 6pm or leave a message in the w4nvu or aa4tm bbs's.This modification is read 684 times.top of page