Built a better PSK31 interface box

Started playing with PSK31 on my mac last year as reported earlier. As I said, I'm running the excellent CocoaModem software.

Until last week I was using the RTS line on a USB serial cable to key the transmitter which made for rather too many cables on my desk so I've jumped in and built a better interface box that has a VOX for keying PTT and includes level controls for both send and receive audio.

The box includes my old audio interface with 600/600 ohm transformers for audio in and out and ads a VOX board I built from a jaycar kit. Initially I ran in to some RF effects that caused the PTT relay to drop out during transmit, but the addition of RF chokes on all inputs and some bypass capacitors seems to have cleared up the problems.

On the back is a 5 pin DIN plug so I can make leads to connect to my rigs. To start I've made an Icom data cable.

So far I've had contacts with New Zealand and Queensland and can hear people in WA, SA and Victoria. We've had a lot of rain recently and I'm not sure that my home constructed balun has kept out the water. (The TV used to black out when I transmitted and it isn't any more - so in my book that's a bad sign...).

Very much hoping to catch up with VK3SL, Les, in Melbourne if he gets set up.