Icom IC-575 (IC 575 IC575) transceiver mods reviews software and diagrams

   
 
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20 November 2024, 2:32 UTC 


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Icom IC-575 (IC 575 IC575)
IC-575
Programming interface schematics for Icom:
Programming software for Icom IC-575 (IC 575 IC575) :
PDF User Manual for Icom IC-575 (IC 575 IC575) :
PDF Service Manual with schematics for Icom IC-575 (IC 575 IC575) :

Mods for Icom IC-575 (IC 575 IC575) :
    Icom IC-575 (IC 575 IC575) General Coverage TX Modification
    Icom IC-575 (IC 575 IC575) Pass band Tuning Modification
    Icom IC-575 (IC 575 IC575) Power control modification
    Icom IC-575 (IC 575 IC575) Restoration of pass band tuning
    Icom IC-575 (IC 575 IC575) Splitting into RX- and TX paths
    Icom IC-575 (IC 575 IC575) Modification of cw pass band (BFO)
    Icom IC-575 (IC 575 IC575) Disabling of SBB squelch
    Icom IC-575 (IC 575 IC575) Very fast AGC
    Icom IC-575 (IC 575 IC575) SSB RF Gain
    Icom IC-575 (IC 575 IC575) Tuning speed
    Icom IC-575 (IC 575 IC575) Frequency range & CTCSS tones
    Icom IC-575 (IC 575 IC575) Freq. steps mod

Icom IC-575 (IC 575 IC575) technical specifications :  Icom IC-575 (IC 575 IC575) technical specifications



Icom IC-575 (IC 575 IC575) Very fast AGC

Problem:

For some modes of weak signal communication, it can be desireable to have a very fast AGC (e.g. meteor bursts with a sharp rise and a long weak "tail"). The standard fast AGC has a time constant of about 2 secs (!), which also means that a noise pulse can mute you for quite some time.

Note: Never use the noise blanker when receiving high speed CW (Meteor Scatter). The noise blanker mistakes the high speed keying for noise pulses, and will seriously corrupt the signal.


Solution:
The solution is to move the "AGC fast" capacitor (C19) to replace the "AGC slow" capacitor (C20). You will loose the "AGC slow" option, but I find "AGC fast" adequate for most signals.

Another solution is to switch out the "AGC fast" capacitor (C19) seperately, but then you will get the problem of finding an appropiate front plate switch. I already tried to use the DATA button, but it cannot be activated in CW.
Note: a strong signal will be seriously distorted in AGC OFF mode.


Implementation:
  • remove C20

  • move C19 to the replace C20