> On Fri, 4 Feb 2022, Paul Kasley wrote:
>>
>
> However, is that the way modern radios actually generate FSK? and CW?
> Or do they actually generate AFSK internally and put it into the audio
> chain?
>
When I used a Yaesu FT-1000D I discovered that it was keyed (externally) like a "true" FSK transceiver but that, internally, the signal was being converted to AFSK and that was what was being transmitted. I realized this after being told my on-air signal was overdriven.

I later switched to an FTDX-5000. The manual for the 5000 has a note under RTTY Operation that states: "In the FTDX-5000, "RTTY" is defined as an "FSK" mode, whereby the closing and opening of a keying line (to ground) causes the Mark/Space tones to alternate. The RTTY mode is not an AFSK based mode in this transceiver and the AFSK output tones from a TNC will not cause Mark/Space shifting to occur. Use the "Packet" mode for AFSK-based Baudot and other data modes."

After switching to the 5000 I never had problems with overdriven signal again, which is one reason I bought the transceiver. There is definitely crud on the air from digital modes transmitted without proper audio adjustment.

The only other "modern" transceiver I've had RTTY experience with was an ICOM IC-765 which was also "true" FSK. So, I can't speak to the really more modern rigs.

Kevin

W5TTY