[RTTY] rtty afsk.

[Hill, Don]

I think we are getting a little technical here which is
good.  But for simplicity sakes, one can consider AFSK to
be when audio is sent from a TNC or sound card to the radio's
audio input and FSK is when on/off (or open/close) keying
is sent to a radio's FSK input.

Do we really care what happens inside the radio?

Just my .02 worth while I sit here waiting for the VP6 to
show up on RTTY.

73, Don AA5AU


-----Original Message-----
From: Kok Chen [mailto:chen@mac.com]
Sent: Wednesday, March 20, 2002 1:54 PM
To: rtty@contesting.com
Subject: Re: [RTTY] rtty afsk.


On 3/20/02 9:36 AM, "Ronald A. Stunden" <sparks@quik.com> wrote:
> The FT 990 is for sure FSK as I have been using it for some time...VE7YC

If you look at the schematics (AF-UNIT F3178000A) of the FT-990,
you will see that the RTTY Key line is used to key a digital sine wave
oscillator whose output is binary encoded voltage levels, with 8:4:2:1
resistor weights feeding an op amp, whose output is controlled by
the RTTY-Level pot.

The FT-990 not an FSK rig, it is a keyed-AFSK rig.

The only rigs which I have used that are FSK are the Omni V and
the Omni VI.  With those, you have to occasionally go in and adjust
a trimmer to get the shift re-adjusted to 170 Hz.

73

Chen, AA6TY



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