[Elecraft] Improved sidetone - Baudline

[Bob Nielsen]

On Mon, Nov 18, 2002 at 12:34:38PM -0600, Bob - AG5Q wrote:
> The url is:
> http://www.baudline.com/
> 
> It looks like it only runs on Linux.

Yes.  I have been looking for an alternative to Spectrogram which runs
on Linux, since both of the computers in my shack run only Linux.  I've
found a few spectum analyzers, but none which would be adequate for
what Spectrogram does.  Thanks for the url.  I downloaded it and
will take a look.

If it doesn't work for aligning my K2, I'll probably create a small
disk partition for Windows 98 and use Spectrogram, but hopefully
baudline will do the job.

> 
> I haven't tried it yet, but it seems like Spectrogram could be used for this
> evaluation too.

I suspect so.

73, Bob N7XY

> 
> 
> ----- Original Message -----
> From: "Bob Nielsen" <nielsen@oz.net>
> To: <elecraft@mailman.qth.net>
> Cc: <matti@mailman.qth.net>
> Sent: Monday, November 18, 2002 12:10 PM
> Subject: Re: [Elecraft] Improved sidetone
> 
> 
> > Can you provide a URL for the "baudline" software?  Possibly this would
> > be an alternative to using Spectrogram (my wife wouldn't appreciate
> > dragging her Windows computer into the shack).  I looked at the Hamsoft
> > site (http://radio.linux.org.au) and couldn't find any reference to
> > baudline there.
> >
> > Thanks & 73,
> >
> > Bob N7XY
> >
> > On Mon, Nov 18, 2002 at 10:18:39AM +0000, Marteinn Sverrisson wrote:
> > >
> > > Improved Sidetone in K2...
> > >
> > > I have not been satisfied with the sound of the current
> > > side-tone in my K2. I have done the side-tone mod, using a 47mH choke.
> > >
> > > Looking at the circuit it is a High-Pass filter with some
> > > peaking in the 600Hz region but it does not attenuate the
> > > higher order harmonics of the side-tone.
> > >
> > > Why not make a Low-Pass filter using the same choke?
> > > I moved the 47mH choke (rs=180 Ohm) in series with
> > > C33 (the 2.2uF cap) and put a new 2.2uF cap across Rp5 pins 7 and 10,
> > > making a genuine LP filter.
> > > The internal resistance rs of the choke controls the Q of the filter.
> > > This makes a huge improvement of the side-tone sound, now it is soft
> > > and sweet :-).
> > >
> > > To make the mod I had to cut the trace from C33 leading to U10,
> > > I cut it next to C33 and inserted the choke across the gap,
> > > soldered it to the C33 pad and the pad for C35,
> > > this is done on the underside of the Control Board. Then solder
> > > a small 2.2uF cap between pins 7 and 10 on Rp5.
> > >
> > > Here are measurements of the side-tone harmonics before and after.
> > > The harsh sidetone is now gone and instead a softer tone is now
> > > generated, almost a pure sinewave.
> > >
> > > Side-tone at F0=600Hz, reference level 0dB.
> > >
> > >                 Before          After
> > >
> > > 600Hz           F0=0dB          F0=0db
> > > 1200Hz          F1=-16dB        F1=-42dB
> > > 1800Hz          F2=-27dB        F2=-42dB
> > > 2400Hz          F3=-54dB        F3=-70dB
> > > 3000Hz          F4=-47dB        F4=-70dB
> > >
> > > Higher order harmonics not visible on the spectrum, with the new LP
> filter.
> > > Measurements done with "baudline" program running on Linux.
> > >
> > > 73's
> > > TF3MA