Re: WSJT-X running RIG split with N1MM and IC-7300
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Rich is correct
Some radios have significant roll off in the audio passband.
Other (newer?) may have none or less and may be much better designed so that the Audio passband in both TX and RX is designed to not have any Audio rolloff when in Digital modes.
As an example all the Flex 6000 series are absolutely flat (meaning no EQ adjustments) from just above 0hz to 10,000 hz (if you sent your filters that wide) in both TX and RX while in Digital operation. Meaning that is you have a 3khz wide TX and RX filter set on a 6000 series radio, you can call and receive up to 3000hz + your Carrier (VFO) setting and this will not affect your output power at all.
For other radios that do recognize digital modes, you may want to consult your owners manual to see if they handle it the same way. If they don't, then using Fake It is to your advantage. You can test this by running WSJTx Tune and start with your TX Freq set to 150 HZ and record your power out on a watt meter (on a dummy load - if you don't have one, ask for one for your Birthday or Christmas). If you don't have a dummy load, then make sure you are on a clear piece of radio spectrum and you can do it on any band since the readings/measurements are not affected by the band you are on. Then move your TX frequency to 250Hz, 400Hz, etc. all the way up until you get no power out. If you graph it, you will get a great idea of your sweet spot/range. When you do this, do not touch your VFO knob.
If audio passband is a bit foreign to you, don't hesitate to ask questions and we will do our best to help explain it. Sometimes the old farts (aka, me) think that newer hams have the same knowledge and understanding and that is a bad assumption. We are hear to help out.
On Sun, Aug 25, 2019 at 5:49 PM ve3ki <ve3iay@...> wrote:
If you were using a transmit audio frequency between 500 Hz and 1000 Hz, QSYing the rig down 1 kHz is exactly what "Fake It" is supposed to do - it moves the audio up by 1 kHz to compensate, in order to put the transmit audio into the 1500-2000 Hz range. That avoids any roll-off in the rig's transmit frequency response, and also avoids any likelihood of audio harmonics getting transmitted.