[Elecraft] Improved sidetone - Baudline

Mon Nov 18 13:35:59 2002

The url is:
http://www.baudline.com/

It looks like it only runs on Linux.

I haven't tried it yet, but it seems like Spectrogram could be used for this
evaluation too.
73,
Bob - AG5Q

----- Original Message -----
From: "Bob Nielsen" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
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
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>
> --
> Bob Nielsen, N7XY                          [email protected]
> Bainbridge Island, WA
> IOTA NA-065, USI WA-028S
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