I recently tried using SatPC32 for CAT control of my Yaesu FT-818nd rig for automatic tuning during a pass of the XW-2B linear transponder satellite. The radio appears to be just a minor hardware refresh of the FT-817 and FT-817nd so I have it configured to use Yaesu FT-817 in the radio control settings. My CAT control interface is using a U5 Link which connects to the accessory port on the back of the radio. Inside the box, it is just an FTDI chip. It is set to the baud rate 38400. I have successfully been using this box with both Ham Radio Deluxe and N1MM for various other controls. However, I had an issue with SatPC32 not making all of the correct adjustments.

From what I can tell, it is dropping commands. The radio was only partly

configured correctly such as setting the USB/LSB modes on VFOs A/B. It was not adjusting the frequency. I had the CAT delay set to the original value of 70 ms and tried increasing it. At 180 ms, it was still having issues, but I finally bumped it up to 300 ms and the radio started responding correctly. I then saw it tuning both the TX and RX VFOs as needed throughout the pass. However, at this delay, it spends a noticeable amount of time in the TX VFO before it updates the frequency and, if I'm not watching carefully, will press the PTT on only to have it jump to the RX VFO to transmit. It also means more time where I won't be hearing the incoming signal if someone else is talking.

Are there any recommendations for improving this situation or could I possibly have a bad (cheap Chinese clone?) FTDI chip that is limiting the rate that commands can be sent? I have not had any issues with HRD or N1MM, but I expect they are sending commands at a lower rate since it's not a constant Doppler shift. Anyone else have a solid FT-817/818 setup?

- Loren K7IW