[Xastir] does Xastir work with Rascal interface?

[BDonnell at ar-northwest.com]

For some amateur modes, both the RX->TX and TX->RX timing has to be controlled pretty tightly - AMTOR and PACTOR come to mind.  A slow change from TX to RX creates a minimum distance that the other station has to be away from your station, so that your radio returns to receive by the time the beginning of his reply bits start arriving at your receiver.  If the other side of the equation, the keyup delay, is too large, then a similar limit is set on the maximum distance a station can be.  These modes were designed the propagation delay in mind.  So properly controlled T/R control has significance.

Also, depending on the TX audio level, source impedance, and the loading by the capacitor/diode combo, the audio tone could become distorted.  Not a big deal for 1k2 packet, but harmonics and distortion of the audio tone would have a very observable effect on PSK31 when those harmonics fall within the passband of the SSB filter in the transmitter. 

73, Bob, KD7NM

> -----Original Message-----
> From: Wes Johnston [mailto:wes at kd4rdb.com]
> Sent: Friday, March 18, 2005 2:38 PM
> To: Kurt A. Freiberger
> Cc: xastir at xastir.org
> Subject: Re: [Xastir] does Xastir work with Rascal interface?
> 
> 
> I've wondered why no one has made one of these units which 
> used a Nchannel FET
> for the PTT trigger.  I would seem to me that diode in line 
> with the gate and a
> resistor and cap in parallel.  Audio could be used to charge 
> the cap and cause
> the FET to key PTT.  The resistor would slowly (like a few 
> mS) discharge the
> cap and eventually unkey the radio.
> 
> Stephen Smith made a vox sound modem interface that uses +8v 
> on the mic jack of
> your radio http://webs.lanset.com/wa8lmf/ham/tonekeyer.htm
> 
> Wes
> --
> 
> 
> 
> Quoting "Kurt A. Freiberger" <kurt at badgers-hill.net>:
> 
> > Jason Winningham wrote:
> > <snippage>
> >
> >
> > > can't tell much about this one from the web site.
> >
> > Except they're mighty proud of them - Around $200?
> > Ack.
> >
> > >
> > > -Jason
> > > kg4wsv
> > >
> >
> > 73/Kurt
> >
> > --
> > Kurt A. Freiberger     Austin, TX	kurt at badgers-hill.net
> > Amateur Radio Callsign WB5BBW  		AIM Handle: WB5BBW
> > "Some people are like Slinkys - Generally considered useless, but
> >   you can't help smiling when you see them falling down the stairs."
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> >
> 
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