When you first bring the dongle up in HDSDR you should be able to see HF band signals when you tune HDSDR to the IF frequency. Of the various SDR radio programs that are floating around the internet, HDSDR seems to be the best for interfacing the RTL-SDR with another radio and then being able to co-ordinate the tuning of the two systems. If you are doing this for the first time, some good instructions are located here. Now we can bring up the RTL-SDR in the HDSDR software. Ideally, use a short piece of 75 Ω coax to match to the RTL-SDR tuner input impedance (but 50 Ω is okay too). It is important to tap in right after the mixer and before the 1st IF band-pass filter, since otherwise the pass band that you can tune with the RTL-SDR as a pan-adapter will be severely curtailed by the IF filter. Usually a little study of the receiver schematic will make clear where you need to tap into the 1st IF signal, and whether the radio design will make this easy or not. On my old IC-745 I had to solder in a resistor at the right spot to get the signal. Tapping into the IF after the first mixer is easy on the IC-751A since there is an unused connector on the RF board that is designed for scope monitoring of signals at this location. Many HF receivers employ a first IF stage, mixing upward to a 45 to 75 MHz intermediate frequency.
To be useful for the HF ham bands, some up-conversion is required.
The device can tune from about 30 to 1700 MHz. My RTL-SDR is the common RTL2832U chip with R820T tuner.
For now, let us get this up and running.įirst a diagram of what we are about to do: Block diagram of hardware and software components. I’ll discuss the performance of RTL-SDR receiver in another segment. Once that is working, then we can look more closely at the actual RTL-SDR receiver performance, compared with the native performance of the parent receiver.
What I will describe are the steps required to use one of these devices as a full-band pan-adapter for a conventional receiver. Here I am adding my experiences to the crowd. Re-purposing the $10 tuner dongle to be an extraordinarily wide-band software defined radio is the subject of countless internet articles and videos. There is little doubt that the RTL-SDR tuner dongle radio receivers are the hottest new thing for the amateur radio experimenter.
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