Locked Re: What should Radio TX Power Setting really be? #wsjt-x #WSJTX_config

Peter Hall, VK6HP


You're probably getting the message that there are a number of ways to get an acceptable RF signal but I believe it's useful to verify - at least initially - the result that you're achieving with a particular setup. The RF output meter is not, a priori, the sole indicator of where the WSJT-X slider should be.  For example, for a given audio interface and/or transceiver sound-card attenuation and gain settings you want to be sure that you're not over-driving the audio stages, one cause of the visible harmonic and other distortion sometimes seen. Similarly, while some ALC systems are fairly benign, the dynamics of others are capable of unduly broadening digital signals.  I find that running the transceiver into a dummy load and monitoring the output with a second receiver and decoder (with spectrum displayed) is invaluable. With most JT modes you have to be very careful of excessive coupling into the monitor receiver but, once that's done, you have the opportunity to familarize yourself, at your leisure, with your computer and radio settings.  You may learn more than you want to know: for example, I can see very low level passive RF intermodulation products in my 630 m antenna, with its very poor, opportunistic ground system incorporating the pool fence.

As far as radio power settings go, in my TS-890S I find the power setting control and the per-band, per-mode power limiting to be useful, especially with an LDMOS amplifier.  The ALC is in the benign class and, while I normally run without ALC showing, signal quality typically remains good right up to the "red" region on the scale.  Your setup is different but the message is that it's not hard to do some very useful monitoring.  Much of the time I use a low-ish cost RSPdx SDR (with one of the antenna input cables terminated), while running the WSJT-X monitoring instance on an old laptop. (The same laptop runs the SDRUno SDR interface and various virtual audio and CAT utilities).

Of course when you believe you have it right there are also remote monitoring options available which, depending on where you live, might be useful.

73, Peter

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