Michael, K1JE said (in part)
> When I first started with RTTY over 20 years ago, we used active filters
> composed of cascaded op-amp circuits (741's worked well). Mark and space
> had separate filters, each 80 Hz wide (nominal). I think most sound-card
> based RTTY decoders emulate this type of filter, we just don't see this
> detail usually. The radio's filters are merely another IF in the
processing
> chain, with more or less limited selectivity.
My first RTTY demod. was a device that ANARTS put out in kit form and was
called a DT-600. The filters consisted of wire wound 'pot cores'. It was
connected up to an old Siemens paper chewer and I used paper tapes to send
out CQ's and other monotonous stuff..... I built mine in the early 1980's
and I still have it.. Unfortunately, I have long ago lost the schematics
and hook-up information for it.. If anyone had or has one of these devices
and is currently using it in conjunction with a computer, I would love some
info on it....
John - vk4cej
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