[RTTY] RTTY fsk? with FT1000MP Yaesu

[Kok Chen]

On Aug 24, 2008, at 10:38 AM, F4DVX David wrote:

> It's possible using my SIGNALINK SL-1 interface? or only TNC?

David,

You cannot use the SignalLink SL-1 with FSK.

The SL-1 is an AFSK interface -- it adds transformer coupling to the  
audio lines (to reduce ground loops) and it has a built in VOX circuit  
that automatically generates a PTT keying signal for the transceiver  
when the SL-1 senses an audio signal from the computer.

You will need to use AFSK.  Place the FT-1000MP in PKT mode, and  
connected through the 5-pin DIN "Packet" connector at the rear panel  
of the rig.  Just connect ground, PTT, data-in and data-out pins  
between the SL-1 and the FT-1000MP.

With good software programs that apply waveshaping to the keying  
waveform, you will transmit a cleaner AFSK RTTY signal than if you use  
FSK, as long as you monitor the ALC meter to make sure not a single  
segment of the ALC indicator is lit (the PKT mode automatically  
disengages the audio processor).  You can also use the same setup for  
PSK31, MFSK16, Olivia and DominoEX.

The SL-1 is probably the easiest way to get digital modes working,  
since it requires only two audio connections to the computer.  But, as  
a VOX device, the SL-1 will not work with low duty cycle modes such as  
Feld Hell or J2A CW, since the VOX delay is too large for those  
modes.  You will also need to make sure no music or operating system  
chimes are sent from the computer to the SL-1, otherwise you will be  
transmitting music and chimes in the RTTY subband when the SL-1 VOX  
engages, HI.

73
Chen, W7AY