But there’s also a fourth method iv) that is both most effective and simple:Īs known from VHF/UHF antenna relais technique one can achieve huge decoupling values when earthing unused pins, i.e.
Their cure effect, and worse their side effects too, are hard to estimate. A third method iii) is to increase the input damping of the final amp (there’s already a 3R-pi input attenuator). Two alternatives curing this ICOM implied design flaw are i) replacing the antenna relais and ii) replacing the decoupling diode by a better one. Even the antenna tuner changes the phase relation and can cause several go/no-go situations. When one of the attenuators is on (for sure not the default for 6m!) the decoupling might be ok.
Depending on part tolerances the IC-756 oscillates on 6m or does not. On 6m the decoupling of both the antenna relais and the decoupling diode D131 is no more sufficient. Hereafter the RX path joins the TX small signal route via IC151 to the final amp. This is caused by a loop-back from the antenna relais (TX/RX decoupling) via the RF board, passing the persistently switched input attenuator (2 relais) and the RX/TX isolator diode D131. Some IC-756PRO (-2) tend to oscillate on 6m. Icom IC-756 PRO II (IC 756 PRO II IC756PROII) technical specifications Icom IC-756 PRO II (IC 756 PRO II IC756PROII) technical specifications : Icom IC-756 PRO II (IC 756 PRO II IC756PROII) TX mods 100 Khz - 60 MHz Icom IC-756 PRO II (IC 756 PRO II IC756PROII) TX expand on IC 756PROII #23 EU models Icom IC-756 PRO II (IC 756 PRO II IC756PROII) 6M oscillation problem Mods for Icom IC-756 PRO II (IC 756 PRO II IC756PROII) : Schematics for Icom IC-756 PRO II (IC 756 PRO II IC756PROII) :
PDF Adjusments Procedures Manual with schematics for Icom IC-756 PRO II (IC 756 PRO II IC756PROII) : PDF User Manual for Icom IC-756 PRO II (IC 756 PRO II IC756PROII) : Icom IC-756 PRO II Instruction Manual
Programming software for Icom IC-756 PRO II (IC 756 PRO II IC756PROII) : Programming interface schematics for Icom: The cool thing about this new setup for Fred is that he makes enough time to investigate all the options and tricks.Icom IC-756 PRO II (IC 756 PRO II IC756PROII) I wasn’t able to fully test his new setup because he pushed me out of the way, that enthusiastic he was! ?
I myself do not yet have a Signalink, but men what cool features do you have then! You are able to record sound of the rig, almost all options are controllable from the program.Īlso figure out for him how to let Windows use the internal sound card and let the HAM-programs use the Signalink. What surprised me was the super duper integration of HRD with the radio. Imported his logbook from LogPA (his current log program). Now download and fire up the latest copy of Ham Radio Deluxe.
After installing the driver for the cable, the laptop did see an extra com-port. Fred did already bought a cable for rig control. So these two things I want to help him with. He did connect the rig via the Signalink to his laptop, but didn’t yet use rig control (Cat-V). Actually this combination works really well! He is doing great in QSO’s! The only thing missing was a good logbook. Since a few months he bought a Signalink USB and works all different digital modes with it. Last weekend I offered a friend of mine, Fred PA3YH, some help with his shack setup.