Using a Mixer to Listen to HF on a RTL-SDR Dongle

Over on YouTube user w2aew has uploaded a tutorial video that clearly explains the theory behind upconverters. Upconverters are commonly used with the RTL-SDR to receive the HF (0 – 30 MHz) bands. In the video he shows how to make a simple homemade double-balanced diode ring mixer for the RTL-SDR and shows its performance in HDSDR.

#174: Using a mixer to listen to HF, shortwave, ham, etc. on RTL-SDR dongle

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Due to only a 8 bit A-D conversion, the RTL-SDR dongles have terrible dynamic range (about 50dB).

Without adequate filtering in the up-converter, it’s a case of garbage in and garbage out.

In the case of a direct sampling implementation, there is no ESD protection, leaving the RTL device very susceptible to damage from static discharge as well as the entire MF/HF spectrum being completely unfiltered and wide open to overload/desense and garbage. The HF reception is possible with aliasing and in practice you only get DC-14.4MHz in the first Nyquist zone, but 14.4 MHz to 28.8 MHz is possible using a bandpass filter.


I like the video and what he did . I think I do better with direct sample . I found that I don’t have to do all that filtering , just a FM trap . I use a MJF 1020c . Now I live In Pensacola and I can at leased pickup half the way around the world .


Wow I would buy this or assemble it. Appears to be a nice alternative to ham it up. Looks like no up conversion losses.