RTL-SDR for HF 0-30MHz


The standard RTL-SDR receives from 25 – 1725MHz, which does not include the LF band from 30-300KHz, the MF band from 300KHz – 3MHz and the HF band from 3 – 30MHz. However with the use of an up-converter, these bands can be received (100KHz – 65MHz). Fig.1 shows the 1st version of the RTL-SDR with the mcx antenna connector, and the 2nd version with the sma connector. The second version is connected via an sma m2m adapter to the HamItUp Nano up-converter. The up-converter requires DC power, so this can be supplied by USB cable or via a BiasTee on the RTL-SDR. In Fig.1 the USB cable (mico-usb to stnd-usb) provides power to the up-converter. I am using a Sabrent USB port extender.

Fig.1 HF Receiving Equipment RTL-SDR + HamItUp NanoUpConverter (Ref.1)

Fig.2 shows the up-converter schematic from the data sheet (Ref.1). The input signal range of 100KHz – 65MHz is low pass filtered then mixed up to 125MHz. A band pass filter then selects the upper sideband USB. Fig.3 illustrates the mixing process for the LF/MF/HF bands. Fig.4 shows a Scicos simulation of the up-conversion process and the results in Fig.5/6.

Fig.2 HamItUp Nano Up-Converter (100KHz – 65MHz) Schematic (Ref.1)
Fig.3 Upconversion Process for LF/MF/HF to 125MHz
Fig.4 Mixer Simulation 640KHz AM Station & 125MHz Mixer
Fig.5 AM 640KHz Baseband 10KHz Tone
FIg.6 125MHz Mixer Output


Fig.7 is a YouTube video showing operation of the up-converter and some signals received in the LF/MF/HF bands. SDR# (Ref.2) is used for reception.

Fig.7 YouTube Video RTL-SDR for HF 0-30MHz

Please send your comments, questions and suggestions to:

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#1 – Nooelec HamItUp Up-Converter

#2. – SDR# Receiver Software

#3. – “Learn Telecommunications by Simulation”