Reply To: Hi From Bruce

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Steven Ollmann

Hi Bruce!

I am excited about WSPR and purchased 20M and 30M modules from TAPR. I purchased two (2) RPi 3 B+ modules and 2.25 AMP power supplies.

The 30M module came up quickly and has been on-the-air for a couple days now.

The 20M module required downloading a GIT hub repository, however the recent Raspbian image (Buster) when compiling complains about incompatibilities in the source that changed in GCC v7.1. Eventually it failed unable to resolve “makedev”.
* Next step was to change OS to Ubuntu, however some issues
* It was getting late but determined to make success, I used the WWoT image and installed on RPi 3.
– I did succeed in bringing it online and properly decode using SDRplay RSPdx.
– When I look at the frequency displayed on WSJT-X, I notice that the main signal is outside of the acceptable range above 1600 Hz.
… I double checked that SDRuno is tuned to the same frequency as WSJT-x and it is.
… WSJT-X is decoding a spur/harmonic that is inband (1400 – 1600 Hz).

* The 20M / RPi is connected to DX-EE dipole I usually use for my Yaesu FT891.
* The 30M / RPi is connected to HF-360 vertical.
* The RSPdx is connected to a cellular antenna inside the house in my office

My question was going to be, is there an incompatibility between WWoT image on the 20M module?

However, when I looked at the output of the 30M module, the main frequency is on the band edge right at 1600 Hz.

This brings me to the software application controlling the output frequency on the RPi’s. Two different RPi’s, two different modules (20M and 30M) and identical images.

I’m thinking that with QRP, I’d want the main energy transmitted to be in receive filter bandwidth.

Best regards,
Steve Ollmann