003: 50MHz to 7MHz 0.4W transverter (2SC1973)


I made this one in 2005 to be on the air not only on 50MHz but also on 7MHz with the QRPP 50MHz SSB/CW transceiver. The RF top amplifier (2SK241) is unnecessary, and it is now skipped. As for the balanced mixer of a couple of J-FETs, IMD was much better than expected, and the trouble of the sensitivity suppression etc. was less in the contest. The final is 2SC1973 often used in the 70's , which was the last one stocked in my parts box for a long time.

As the operation was very comfortable, I frequently used this set while I was in JA7/Hachinohe area for five years. It is comparatively easy to make contacts to the Midwestern of the US with such a low power on 7MHz. and the high light was QSO with Brazil and Argentina in the ARRL DX contest.




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