Q At a recent estate sale I picked up a Daiwa CNA-2002 automatic antenna tuner. Unfortunately, there was no documentation whatsoever. Can you tell me anything about this unit?
A Daiwa manufactured the CNA-2002 in the early ’80s. It is the higher-powered cousin of the CNA-1001, which was reviewed in the November 1981 QST.
These units were among the first automatic HF antenna tuners designed for amateur use. The CNA-2002’s tuning function was limited, though. You had to select the band manually, then apply 10 W or less while briefly pressing the TUNE button on the front panel. When the button was pressed, the control circuitry in the CNA-2002 would activate a dc motor and a system of gears to rotate two small variable capacitors. The SWR sensing circuits would trigger when the SWR dipped below about 2:1, abruptly stopping the motor. At that point you could accept settings the tuner “found” for you, or use the FINE TUNING control to reduce the SWR even further. The idea was to diminish the tedium of operating an antenna tuner.
The CNA-2002 was rated for 1.5 kW, but that was a PEP rating, not continuous power. The small, encapsulated variable capacitors had a tendency to arc at 100% duty cycle power levels greater than 500 W.
From QST March 2000
