ICOM IC-756 Pro III Performance on AM

[W1AEX]

Updated 6-26-2010:  The link below has a few simple ideas about working around the aggressive ALC problem and the hard-coded DSP limitations of the 756 Pro III without any internal modifications to the rig itself. If you currently use your 756 Pro series rig for digital communications through one of the common computer interfaces, some easy improvements in AM performance can be made by using "real-time" computer processed audio that is generated by the free Voice Shaper software and then ported out from the computer sound card into the audio port in the back of the Pro III. This is pretty much a zero-effort-project if your digital interface is already installed! A number of mp3 files are included at the link to give some idea of how the Pro III behaves while transmitting in the AM mode with different EQ and compression settings.

Two small audio samples are included here to help show the difference between the stock AM audio and the processed audio with the internal ALC defeated. These were created by using the line output of an FRG-7700 receiver, connected to the line input of one of the station computers, to record the Pro III with Adobe Audition as it sounds on the air. This is a project in progress, but it seems worth a little effort given the large number of 756 series rigs out there, and the excellent AM receivers they have.

http://www.w1aex.com/756AM/756AM.html

[W2BX]

Updated 6-26-2010:  The link below has a few simple ideas about working around the aggressive ALC problem and the hard-coded DSP limitations of the 756 Pro III without any internal modifications to the rig itself. If you currently use your 756 Pro series rig for digital communications through one of the common computer interfaces, some easy improvements in AM performance can be made by using "real-time" computer processed audio that is generated by the free Voice Shaper software and then ported out from the computer sound card into the audio port in the back of the Pro III. This is pretty much a zero-effort-project if your digital interface is already installed! A number of mp3 files are included at the link to give some idea of how the Pro III behaves while transmitting in the AM mode with different EQ and compression settings.

Two small audio samples are included here to help show the difference between the stock AM audio and the processed audio with the internal ALC defeated. These were created by using the line output of an FRG-7700 receiver, connected to the line input of one of the station computers, to record the Pro III with Adobe Audition as it sounds on the air. This is a project in progress, but it seems worth a little effort given the large number of 756 series rigs out there, and the excellent AM receivers they have.

http://www.w1aex.com/756AM/756AM.html

I assume you can run an external analog audio chain into that same audio port on the rear panel. I have a Pro III ,think ill give it a try. 

[W1AEX]

Yes, you can certainly do that. I ran audio right into the little interface that I used for the digital modes. The tight bandwidth constraint in the PRO III firmware was still present of course but it was passable as long as the heavy-handed ALC was defeated with the little battery trick.

73,  Rob W1AEX