Dongle SDR receive and RasberryPi 3 TAPR shield 100mw transmit

4 posts / 0 new
Last post
Last seen: 1 year 2 months ago
Joined: 2012/12/28 - 21:30
Dongle SDR receive and RasberryPi 3 TAPR shield 100mw transmit

Hi All, I just thought I would pass along a set up I have been using for WSPR that is relatively low cost but seems quite effective. On receive I am using a NooElec dongle plus GQRX SDR software plus WSJT-X 1.6 on an very old AMD dual core laptop converted to Linux Ubuntu from Vista. Runs about 75% cpu. On Transmit I am using a RaspberryPi 3 runny WsprryP1 with the TAPR 20m Shield (which I understand they are seriously considering producing another batch of) producing 110mw according to my power meter. My receive antenna is an MFJ tunable loop mounted 12ft above ground on my garage roof. My transmit antenna is a low (avg 15ft) 48 foot non-resonant dipole fed with balanced line to an unbalanced antenna matcher with a balun. I leave the AGC on fast in GQRX with no transmit receive switching and get a +23 db report of myself on WSPR with no seeming damage to the dongle front end--using separate but closely spaced antennas and only 110mw. This set up is in down town Tucson, AZ, USA and is far from a ideal QTH. You can check out the results using my call in the WSPRnet data base. My most distant reception was VK2EFM 5 watts at 0552 and 1452 gmt 9/28/16 at -19 and -23 db, 7810km in the last day. I was so surprised by the results of such a simple cobbled up set up that I thought I would at least pass it along. Using WSJT-X for WSPR, the dongle is not far off the performance of my IC7000 or K3 on receive. 110mw produces a surprising number of spots across the USA and Western Canada which is comparable to my normal distribution of spots at 100w CW although the 110mw is probably only equivalent to 2-3 watts CW given WSPR performance advantage. Just a FYI post.
Jim Carson KB4DXV