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
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