Modifications for the ICOM - RogerK

Hello....on the mod to expand the receiving capabilities, (powering up while holding the multi and squelch keys), If the xcvrwas previously programmed via Icom software and cable via PC, and the mod was enabled, you cannot re-program the radiovia PC. The software reports an error that the version doesn't match.....the only way to access the xcvr via PC again is to do aCPU reset (power up while holding the squelch, vfo, and, mr).....Solution.You can reprogram the radio if it was previously programmed. You just have to rerun the CS-T81 setup option that's in thestart menu with the radio turned on. It will retrieve the programming info from the radio. I've done it myself several times. Iuse my opened T81 with my software and program my buddy's newer t81s that the receive trick does not work on just finewith this little tip.Date: 09-12-2001 User comment From: realist946Subject: Does not work on all!This Modification DOES NOT WORK ON ALL RADIOS. Please do not e-mail me for more info. I just thought I would point outthat it is not valid for all of these radios. Additionally, on some, you must enter VFO Mode then turn the radio off to get the "AllSegments Display".This has been confirmed by ICOM as well. So if you plan to purchase this radio in the hopes of using this mod, be careful. It isnot valid.Date: 13-01-2002 User comment From: anonymousSubject: Serial numbersAfter asking around, it appears that the "new" production IC-T81A had the majority of the extended RX tables taken out of themicroprocessor due to FCC part 15 rules.The IC-T81A has a 1st IF in the 70 MHz range. The image response was poor, and so you could tune in the cell stuff via theimage (140 MHz away, using this IF freq as an example).The FCC and the ECPA now require a minimum of -38 dB of image rejection for cell freqs on comm radios, scanners and yes,HTs. I cannot test my IC-T81A because it won't go into that band. But I hazard a guess that the radio didn't cut it in thatdepartment, so the microprocessor was "updated" to reflect the new reality.To my understanding, there have been at least three, steadily increasing levels of "big brother" wrt to the ECPA and how itaffects what your radio toys can do/can't do in the 800 MHz region.Maybe this also explains why the ICOM "vaporradio" IC-T82A never made it to market...FYI-my IC-T81A is serial 04553 and it won't do anything above 470.000. This pissed me off as I use my radio to listen to US TVchannel 17, where I work (493.75 MHz audio). Oh well, the IC-T8A I got today does just fine, and the loss of 1200 MHz doesn'taffect me one bit as there is zip activity where I am located.This modification is read 3421 times.top of page05-09-1999(IC-T81) IC-T81 Frequency ExpansionRemove the Diode D53 and D61.