Reader David Forsman, WA7JHZ, read the round-up of RTLSDR upconverter choices and sent me a photo and build schematic of one he designed which was featured in the January 2013 issue of QST, the ARRL‘s monthly magazine.
This circuit up-converts frequencies between 2.3 MHz and 43 MHz by 125 MHz (127.3 MHz to 168.0 MHz) for driving the Realtek RTL2832 quadrature decoder DVB-T device with Elonics E4000 tuner chip with USB 2.0 output. It also incorporates an input bandpass filter (BPF), diode limiter, RF attenuator, and amplifier.
The filter’s response curve:
David reported he’s built two of these up-converters with good sensitivity on 20 and 15 meters. I think I have all the parts except the crystal and coils to build this on hand, so this might be a good excuse to sting my antenna up again and try it out. Thanks David for sending this in!