There is a solution for recent SW-3B rigs that have a long T/R switching time. On my rig, bought Feb. 2024, the T/R switching time was 600 ms. It was long enough that I missed the first few characters in callsigns coming back to me. Judging from videos of earlier SW-3B prior to 2022, the T/R used to be near-QSK.
The value of a capacitor C37 on the RC network applied to the MUTE signal going into the receive section is too high. The schematic says 0.01 uF, but I measured mine as 0.1 uF. This would apply an extra long time constant on the switching. When I replaced my C37 with a 0.01 uF cap, my T/R went down to near-QSK.
This part of the schematic is similar to the Elecraft KX1, where the cap in the RC network is also 0.01 uF. Now my SW-3B and KX1 have similarly short T/R switching times.
The cap is easily accessed on the bottom of the board and is a fairly easy job. It made this rig an even better one, combined with the recent improvements on CQ memory flexibility and screen visibility.
73 Mike N9OHW
Edit: added photo of the bottom of my board where I changed C37, the SW-3B schematic from Venus’s website, and the KX1 schematic from Elecraft’s website, both showing 0.01 uF for this capacitor.
