[RTTY] Opto Couplers ?

[Robert Webb]

Hi all and a Happy new year from sunny England. I have been building an FSK
interface between serial port and 1000MP. All the designs i have seen use
Opto Couplers but which ones ??. I have used a low current version from
siemens SFH618-2 and seems to be working but no fsk out from the radio.
Works ok with the FSK from a Kamplus and my meter suggests that the output
from my interface is working but no joy. Any suggestions B4 saturday 16:00
would be appreciated, all the very best de Robert G0URR K