20m CW transceiver SW-20+
Japanese : Dec. 6, 2013, English : Dec. 7, 2013
Last update : May 6, 2015
Japanese page is here.
Overview of SW-20+
I built a 20m CW transceiver 'SW-20+' in December 2013.
SW+ series kits had been supplied by Small Wonder Labs, but now their all
kits seems to be discontinued. As of May 2015, the 'Rock-Mite' series are continued called 'Rockmite ][ ' by a successor QRPme.'FREQ-mite' is also supplied by the Four State QRP Group.
My SW-20+
（ For modification, a push switch, a volume control, two LEDs are added
on the front panel. ）
( There are holes on the top plate for speaker addition. )
SW-20+ PC board
Rear panel of my SW-20+
（ The phone jack and the DC jack are not original. ）
My SW-20+ overview (modification points)
Inside of my SW-20+
（ There is a 'FREQ-mite' in the left front. )
( There is a LM386 audio amplifier in the right front. ）
( There is a speaker on the top plate. )
Main modification points are as follows:
Front panel of my SW-20+
( Some letters are added. )
Speaker addition
A LM386 audio amplifier, a thin speaker of 57mm in diameter and a volume control are added.
MC-6 -- LM386 audio amplifier kit -- supplied by the AITEC Electronics
Labs. in Japan
Frequency indication
In order to indicate the frequency, Dave Benson K1SWL's 'FREQ-mite' supplied by the Four State QRP Group, a Morse-readout frequency-annunciating device, is installed, and a push switch is added on the front panel.
'FREQ-mite' ( left photo )
An audio frequency low-pass filter and a volume control are added to the
output of the 'FREQ-mite' ( right photo )
Upgrading of the low-pass filter after the final transistor
One more stage is added to the low-pass filter after the final transistor.
Low-pass filter after the final transistor
References
Toru Kato, JG1RVN：'HF mono-band CW transceiver -- Building of SW+ series
which came from USA', Mobile Ham, Mar., 1999, p.20 - 25.
Past images from Dec. 2013 to May 2015 are here(Japanese).
Copyright (C) 2013-2015 by MATSUMOTO Koichi, JN3DMJ