I know a lot of QRP Labs products can be programmed with a TTL-level serial protocol. The USB to serial adapter products that use a genuine FTDI USB serial chip seem to be the most compatible and reliable.

I helped design the Masters Communications Ultimate FTDI TTL serial adapter. This uses a genuine FTDI USB chip and has eight LEDs to monitor the TXD, RXD, and ALL eight handshaking lines that are present on a DE-9 serial connector. It's like getting a DE-9 breakout box with the adapter The only thing it lacks is TTL to RS-232 converters. From my limited research, QRP Labs products only need TXD, RXD, and GND signals but the handshaking lines could be used for other purposes.

The product is offered as a kit or assembled. Granted you can buy a USB to TTL cable for about $20US that probably has no LEDs and only limited handshaking capability, and that may be all you need, but if you like to see blinking LEDs and want the flexibility of having the six handshaking lines, you might want to look into this product. Go to www.masterscommunications.com then look for "Ultimate FTDI" and contact Kevin directly.

Bob M.