SDR techniques for Boatanchor Radios

W9RAN started playing with RTL-SDR dongles about 6 years ago, and knew they were going to have a big impact on the radio hobby.   But since these $15 receivers only tuned the VHF and UHF bands, he designed a wideband upconverter to make HF coverage possible, and described how it worked in an article in Jan. 2013 QST "Cheap and Easy SDR".   The "RANVerter" as he calls it has evolved since then to become an SDR board for use with small Linux computers like Raspberry and Orange Pi.   

At Jonesborough 2018, Bob showed the latter - a board about the size of a matchbook that fits inside the Orange Pi enclosure and wirelessly streams data to a nearby PC, phone or tablet.   SDR software has evolved too - from an application that required a pretty high-end PC back then to a client-server approach that makes it possible to use any device which has an HTML 5 capable browser.   

It's an ideal way to add a panadaptor to a boatanchor radio since vintage radios have IFs in the 455 to 10.7 MHz range - all of which can be tuned with the RANVerter SDR.   OpenWebRx is a free SDR app developed by a young ham in Romania that is becoming popular for use with remote SDRs, and also works well as a panadaptor.   The signal is picked off of the first mixer so several hundred kHz on either side of the IF frequency can be seen and zoomed-in to provide as much resolution as desired.  And it's more than just t a visual display - complete DSP audio demodulation is available with selectable modes and filters that can be tuned independently from the vintage receiver or transceiver.   This makes it easy to listen to other signals up and down the band or even to receive AM on a SSB transceiver that has no AM detector.   

This blending of old and new technologies brings modern features to older radios without hacking or modification.   Not only can you see and  hear your Swan or Heathkit or Hallicrafters on your smartphone or wi-fi tablet, but with dynamic DNS you can do so from anywhere an internet connection is available - from the back porch to the other side of the world!