Tonight I made the first successful decoding of WSPR on the 630 m band. What inspired me was all the talk on the Elecraft reflector on the new synthesizer which in addition to having less phase noise, also allows the K3 to go below 500 kHz. I don’t have that synthesizer, but the discussion reminded me of the low frequency converter I built many years ago. It converts 0-1 MHz to 14-15 MHz. Using the KXV3 transverter interface of the K3 it was easy to interface and get up and running.
The first signals I decoded are shown in the water fall above, and their origin in Germany and the Netherlands is shown in the next figure.
According to WSPRnet, PA0A’s 2 Watt transmitter is 784 km away from me, and DK7FC’s 1 Watt is 1164 km away.
The converter is based on a 74HC4053 switch used as a mixer with a 74HC04 for a 14 MHz oscillator. It is based on SM6LKM’s design, but with a different oscillator frequency and a simplified output filter. It is one of many small projects that I have built in Altoids tins. The antenna used was my trusty old 80 meter horizontal loop with a 4:1 Elecraft balun.
Perhaps the next step is to finish the 475 kHz filter of my Ultimate 3 WSPR transmitter and see if others can receive me? That is going to be more of a challenge antenna-wise.