Cyclone 40

The Cyclone 40 is a David Cripe, NMØS, transceiver design with PTO tuning which covers the entire CW portion of the 40M band.

The receiver is a very quiet superhet with very good specs. It features an excellent 500HZ 4 crystal IF filter, outstanding full QSK, and an AGC which is an innovative audio derived design - very fast, smooth, and silent. MDS (Minimum Discernable Signal) is -125, which is below the normal 40M band noise level. It's IMD3 is 90 dB which better than most commercial gear, and its IP3 is +10 dBm another very good number The frequency readout is via a counter with audio CW output, 3 or 4 digit and 1 kHz or 100 Hz resolution.

The transmitter sports an efficient Class E Final - one of Dave's tradmarks. Filtering is excellent with all harmonics and spurs - 50dBc, and it makes 4 to 5 watts into 50 ohms.

Of special interest is that Dave has incorporated an octal buffer IC, a 74HC240, to handle the changeover from receive to transmit. All in all a very innovative design, which is another hallmark of NMØS designs. With a small PTO mod, it is a stable, easy, and pleasant to use rig. As proof of that, I have 188 qsos on mine as of this writing.

Revised 4 May 2014
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