ORIGINAL MESSAGE:
On Wed, 13 Jun 2007 10:50:39 -0400, Stephen & Marilyn Haines
<shaines@chaconet.com.py> wrote:
> From a RTTY newcomer: I'm using MMTTY, a soundcard, and an FT-757. If I
>keep the audio drive to the "phone patch in" connector on the rear of
>the rig to a level just below where the ALC indicator begins to move, I
>get around 25 watts out. I don't know precisely, but the MFJ tuner
>indicates roughly that.
>
>Is that the correct operating procedure: no ALC indication? From what I
>can tell, the tones are clean, and psk31 with MMVARI also works.
>
>Secondly, is 25 watts enough drive for a small amp? Say, the Ameritron
>811 or 811H, or the solid state mobile amp? Would that be the easiest
>way to end up with 100 to 150 watts output.
>
>73 from Paraguay, Steve ZP9EH
------------ REPLY FOLLOWS ------------
The answer depends partly on whether you are using AFSK or FSK input
to your transceiver. With FSK (highly recommended), the ALC and/or
compression have no effect on signal quality. Set your drive to
anything you like.
With AFSK, it is almost the same but not quite. You can drive your
transceiver much harder than with PSK31 for example, because RTTY is a
constant-amplitude signal. Don't go too far, though or you might
generate distortion within the audio part of you rig, although the RF
part will be unaffected. Your transmitted signal will still be clean
except that you will have two or more signals on the band at once, due
to the harmonics of the audio drive frequency. You will hear this on
the air from time to time. Again, do FSK if possible and this can not
happen.
Having never used 811's I can't comment on drive level.
Bill W6WRT
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