Note
QST, Mar 1973, p. 168.
QST, Aug 1974, p. 152. (420A)
QST, Dec 1976, p. 184.
QST, Aug 1977, p. 152.
A low-power electronic keyer using complementary CMOS integrated circuits. The EK-420 offers effortless, self-completing dots, dashes and spaces, dot memory, iambic operation, built-in side-tone and 4-inch speak-
er, built-in power supply and a reed relay for grid-block keying or solid-state rigs.
The keyer operates on 115 VAC or +4.5 to +14 VDC. Because of CMOS circuitry, the EK-420 consumes only 0.5 mW during standby. When keying, power consumption rises to 180 mW. This allows extended operation on an inexpensive 9-volt battery. A rear-panel accessory socket allows instant connection an optional 2048-bit (200-character) memory unit. Front-panel controls include sidetone volume and pitch, weight and speed, tune, self-test, and AC/battery selector switch.
All eight ICs, three transistors and the reed relay plug in to allow easy field
service.
The EK-420A incorporated measures to eliminate faulty keying due to contact bounce. Its susceptibility to RFI was also reduced.
