Recently I have been asked what I use to generate a signal on 630-meters. There are a lot of ways to do it, of which I use two, and currently the only commercially available rig that supports 630-meter as well as 2200-meters are the newer Flex rigs which take into account the band pass requirements with filter changes. That’s great but what about the guy that wants to use an existing HF rig that might not be so easy to perform the MARS/CAP mods?
Enter the MF Solutions 630-meter transmit downconverter, developed and distributed by John Molnar, WA3ETD / WG2XKA, and Pete, N1DYL (SK). Using an HF rig transmitting an IF signal typically residing in the HF bands and mixing with a LO (about 475 kHz away from that IF freq), a signal can be generated from 472-479 kHz quite easily. Filtering and amplification can then bring the signal up to useful levels. This downconverter has many options available, including 10 MHz LO option for GPSDO and RX pass through and is considered an improvement on the G3XBM design, which I started out using in 2012. At 12V, I can generate 22 watts at around 85% efficiency. I attenuate and square the output signal to drive my GW3UEP amplifiers. This process has been flawless. It is important to point out that this converter is Class D/E so it can only be used with non-linear modes. That’s OK as you see non-linear modes almost exclusively on 630-meters due to a higher degree of compatibility with band conditions.
See the flier below for the MF Solutions converter. I am available to answer questions and orders can be made directly to John Molnar at WA3ETD@gmail.com.
Download the PDF for the converter here.