[RTTY] Distortion

[A.J. Cioffi]

Generally speaking, if you are using the FSK circuit of your radio, you need
not adjust anything other than your power output since the radio is
generating the Mark and Space tones.  One already assumes that the radio is
in functioning order for this to be true, so there will be no distortion.

If you are using AFSK (where an external device is creating the tones) those
levels of audio being pumped into the audio circuit need to be at a certain
level; enough of a level to produce an acceptable output while also being
able to crank it up to 100 watts without distortion.  I have found through
experimentation with most sound cards, a 48:1 voltage divider works very
well for AFSK use on the 1000MP.  Anything lower or higher will greatly
attenuate the inbound level or over drive the audio circuit.  You should be
able to run 50 watts of power without seeing many (if any) ALC levels.  This
is all predicated on using the PACKET receptacle. I have not tried the mic
connector although I don't believe that there will be much of a difference.

Remember that there are a couple of inbound adjustments that need to be
made.  Your sound card and the mic gain.  In order to minimize the infinite
amount of variable between the two, keep your sound card at a fixed level.
Adjust your mic gain on the radio for your desired output power.  You should
not see any major ALC levels on the MP.  Then - have fun.

Tony - N2KI
SYSOP - N2KI DX CLUSTER
dxc.n2ki.com:7300
RF Gateway 145.650
Website: www.n2ki.com
DX Spoken Here


> -----Original Message-----
> From: rtty-bounces at contesting.com [mailto:rtty-
> bounces at contesting.com] On Behalf Of Phil Duff NA4M
> Sent: Tuesday, 24 August, 2004 22:47
> To: rtty at contesting.com
> Subject: Re: [RTTY] Distortion
> 
> I use my 1000MP's RTTY (FSK) DIN connector "shift" input (pin 1) driven by
> a COM port TxD line via a simple homebrew keying interface that uses a
> transistor and resistor.   The COM port is driven by MMTTY or other RTTY
> s/w that uses the MMTTY engine.
> 
> So - with this scheme there's no levels to adjust that I know about.  I
> assume that the MP's RTTY shift input only needs to be toggled via the
> COM
> port TxD line and interface to drive the internal 1000MP generator.
> 
> 73 Phil NA4M
> 
> At 02:02 8/25/2004, Don and Diana Cunningham wrote:
> >Phil,
> >You have to turn down the audio from your AFSK generator, which I
> assume is
> >the soundcard output.  Does your "interface" have a means to adjust
> audio to
> >the mic input on the rig?? If not, you will need to build up a "padder"
of
> >some sort to do that.  There is an awful lot of output from my soundcard,
> so
> >would HAVE to have some way to cut it back here to use it.  Hope that
> helps!
> >73,
> >Don, WB5HAK
> >----- Original Message -----
> >From: "Phil Duff NA4M" <na4m at arrl.net>
> >To: <rtty at contesting.com>
> >Sent: Tuesday, August 24, 2004 7:44 PM
> >Subject: Re: [RTTY] Distortion
> >
> >
> > > At 18:53 8/24/2004, Kok Chen wrote:
> > >
> > > >So, if you operate without a single of the ALC bars lit, then IMO you
> are
> > > >just as clean as operating "FSK" from that rig.
> > > >
> > > >I used to have my 1000MP's meter set to show Power/SWR.  Now
> that I have
> > > >transitioned from FSK to AFSK, I seem to have my meter sitting most
> of
> >the
> > > >time at Power/ALC :-) :-).
> > >
> > > I have an 1000MP
> > >
> > > I see no adjustment for FSK/AFSK drive level in RTTY mode to have no
> ALC
> > > indication.
> > >
> > > All adjustments I make to RF power, MIC, or PROC levels on front
> panel
> >have
> > > little effect on indicated ALC in RTTY mode.
> > >
> > > The 1000MP manual indicates that the MIC control should be set to
> >mid-scale
> > > for RTTY operation and then adjust output power.  This results in an
> ALC
> > > indication of about mid scale with small variation depending on
> output
> > > power adjustment.
> > >
> > > 73 Phil NA4M
> > >
> > >
> > > .--. .... .. .-..     _. ._ ...._  _ _
> > >
> > >
> > > _______________________________________________
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> > > RTTY at contesting.com
> > > http://lists.contesting.com/mailman/listinfo/rtty
> > >
> 
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> 
> 
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