John's Musings


Yeah, Me Neither

How to use an UpConverter with SDR in GQRX

As with most geeky things I've found that NOBODY hardly puts those "seal the deal" details on the internet. Smart guys will say something like "balance the decombobulator" without actually telling you how to do it. Hey, they know how to do it and that's what matters.


In fact that is the whole premise of my webpage and my blog. To capture that minutia and those details and write them in a step by step easy to follow process.


First of all, what is an UpConverter? An upconverter allows you to get roughly between 0 and 24 MHz. There is where you find AM radio, Shortwave, and HF transmissions. Just beyond 24 MHz, and usually reachable with an upconverter is CB radio as well. So your basic SDR dongle doesn't quite reach that. Well actually one does. This one.



Here's how you do it in GQRX. When launching GQRX for the first time or while selecting "Configure I/O Device" here's how to get the HF frequencies........


Select the Realtek device and make sure the Device string says


rtl=0,direct_samp=2


beneath that set LNB LO to:


-125.000000 MHz




Score. You might need to make sure "No Limits" is selected In the "Input Controls" tab as well in order to properly tune.




That makes that RTL-SDR an awesome little device. For $25 and some geekery you can listen to HF band radio on the cheap. An upconverter always works best though.


Here are the other two I have. An AirSpy Spyverter and a NooElec Ham It Up.




For the NooElec set it up like below. It is ALMOST exactly the same as above. Simply hook it up, then remove the ,direct_samp=2 from the Device String. The LNB LO is also -125.000000 MHz. Here's a pic with me getting a great signal from the local AM radio (1450).





Lastly........The AirSpy R2 and Spyverter. Very similar but different values.


In the device string type:


airspy=0,bias=1

with an LNB LO of -120.000000 MHz




And Bob is your uncle.


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