In reply to MM0FMF:
The level shifter will be of the same order of complexity as a PTT
switch so you don’t gain anything. In fact it will be more complex.
Actually, the whole process can be done with a couple of MOSFETs for switching and some resistors to set levels. See: http://www.botkin.org/dale/yaesu_if.htm
I’m not saying its good for the job being discussed in this thread, but if ever you need to shift RS232 to TTL cheaply and easily, it works. I use one to program my VX-6 on a regular basis (one set of freqs for homes in G and GW, another for visiting the YL’s folks in London).
Ham Radio Deluxe
Granted, the GUI is hideous by comparison to some products, but once you get your head around it, it is functional. I think the decoding is a work of art - it runs with very minimal overheads and will decode where other programs wont. Its also worked well where others (MixW in my case) could not figure out what to do with some dodgy on-board sound on certain laptops. Plus, the shareware version is very and indefinitely functional.
Hmmmm. I’ve just realised, I’m actually talking about MultiPSK, not Ham Radio Deluxe! I’ll leave the above bit of soapboxing in, just in case it causes someone to discover MultiPSK.
Back to the topic: I think I might just rob the PTT bit from this chaps interface: http://www.vk2zay.net/article/161 and not bother with the isolation. Seems like it work for him.
Thanks for all the replies.
[edit to make links work]