[RTTY] FSK is bad?

[Joe Subich, W4TV]

On 10/25/2016 5:59 PM, Jeff AC0C wrote:
> As Joe likes to point out, full control with all knobs turned to 11 is a
> problem.  But I think that a guy who has learned to use his mic gain
> control can learn how to set his AF drive level on AFSK.

It is mostly a problem with those who pump the output of their sound
card directly into the mic jack without an attenuator.  Most rigs -
particularly those (Kenwood, Yaesu, Ten-Tec) designed for use with a
dynamic mic - have a fixed gain preamplifier (either a common emitter
NPN transistor or a low power op-amp).  Driving that preamplifier which
is designed for an input of about 5 mV with a 4V P-P signal guarantees
the audio presented to the mic gain stage is already heavily clipped
square waves.

One is far better served connecting the sound card output (with the
proper level adjustment network) to the transceiver's "Patch", "Data",
"PKT", or ACC jack which are typically designed for 100 - 200 mV drive
(25 to 30 dB higher than the typical dynamic mic) and do not have an
"uncontrolled" stage between the input and the mic gain control.

73,

    ... Joe, W4TV