To use a 5351 for RTTY (FSK) you can use two of the PLLS set for the desired
MARK and SPACE frequencies and use gateing with the UART Tx signal.
That comes close to how it was done in the OLD DAYS with a FSK VFO and a
relay.
This way I could run RTTY on Bob Macklin
K5MYJ
Seattle, Wa.
"Real Radios Glow In The Dark"a QRP rig connected to a laptop PC for the TTY
terminal.
toggle quoted message
Show quoted text
----- Original Message -----
From: "Shirley Dulcey KE1L" <mark@...>
To: <
[email protected]>
Sent: Wednesday, August 07, 2019 6:17 AM
Subject: Re: [qrp-tech] DDS Options???
That's normal for a PLL. DDS is the way to go for fast frequency
changes, like you need for fast frequency sweeps or spread spectrum
modes; they can change frequency in microseconds.
The Si5351 can be reprogrammed on the fly but it does not change
frequency very fast. I tried to do a frequency sweep and found 3.5
milliseconds to change which severely constrained the number of
frequencies I could use.
