I have not seen any practical designs for using BITX20 for PSK31
mode. I am still working on completing the assembly but would like to
learn more about what mods can be incorporated as I am building. Some
ideas that I have thought about are:
1. Implementing VOX so that PSK31 can be used using VOX switching.
2. Using a transistor switch for PTT switching (similar to design
used in Small Wonder Labs design).
3. Building in the USB & LSB mode in the BFO (similar to the one
illustrated by Farhan in his 2 band rig).
Any ideas of implementions that can be uploaded to the files section?
Arv Evans <arvevans@...>
Check out the FILES section and you will find several suggested circuits for the features that you mentioned. There are two different VOX circuits there (I use the all-transistor version). There is a circuit in FILES for adding RIT, and a bookmark in the LINKS section showing more info on this circuit. My circuit for transistorized PTT is also in the FILES section.
Adding the interface for PSK-31 has been discussed on this forum in the past. All that is necessary is to take off the high-side of your Volume control with a pair of resistors to get the audio level down to where it will match the microphone input on your PC sound card. The PSK transmit is handled by adding another resistive attenuator to match sound card output levels to the microphone input level of your BITX transceiver. In my BITX20 I put two RCA-jacks on the rear panel and connected these to the above-mentioned attenuators. The VOX works fine to perform Rx-Tx switching for PSK.
On Fri, 2004-09-24 at 02:03, null1969 wrote: