[Elecraft] Sinewave Sidetone Mod

[Mike Harris]

Hi,

One of the tasks completed this weekend was the installation of the 47k ohm
part of the sidetone mod.

The resistor was added without trouble and done with care can look neat and
tidy.  Before I did the mod I took a spectrum of the sidetone using the
inevitable Spectogram under the following conditions:

K2 audio source - KPA100 external speaker socket
AF and RF gain fully CCW
"Spot" activated - 700Hz tone.

The tone was set to 40dB on the Spectogram (v7) display, K2 StL level set to
012.

Before:

700Hz      40dB (reference) all other readings relative to 40dB
1400Hz  -23.9dB
2100Hz  -23.8dB
2800Hz  -36.1dB
3500Hz  -32.8dB

After:

700Hz      40.0dB
1400Hz  -31.1dB
2100Hz  -26.7dB
2800Hz  better than -40dB
3500Hz  -38.3dB

The sidetone is audibly cleaner and a beat with the 28MHz birdie was much
easier to hear.  Not a bad improvement for one resistor.  I didn't fit the
inductor 'cos I haven't got one.

Regards,

Mike VP8NO (IOTA SA-002)
K2/100 #1400