Thursday, 20 February 2014

Output gain control in digimode working - hints

When running digimodes, the controlling of the RF output in older or "simpler" transceivers can be a little bit tricky. The reason is that the AF gain is adjusted according to human voice and thus it depends on where on the waterfall spectrum you are sending. You might have noticed that the gain is smaller at the edges of the waterfall.
Output power as function of frequency. In this example HRD DigitalMaster and my IC-718.
Previously I wrote how this issue is handled with Ham Radio Deluxe's DigitalMaster: using the centering button and filters. This helps also greatly in QRM/AGC issues.

In JT65 working I mostly want to see the full spectrum, and in JT65 software there is typically no centering button. In the HB9HQX edition of JT65-HF this is solved neatly with a gain control window:
The audio gain control window in JT65-HF HB9HQX Edition
The gain control window above is not needed, when I work with my TS-850S, because there is a handy mic gain knob at the front of the rig. However, there are no such handy knobs in simpler transceivers, like my IC-718, so the gain control window is crucial for convenient working.

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