Note
The AT-1000 is a fully automatic antenna tuner for high power amplifiers. The AT-1000 is intended for use with most tube or transistor amplifiers with an ouput up to 1,000 watts SSB. It will tune dipoles, verticals, Yagis or virtually any coax-fed antenna.
The LDG design uses banks of fixed capacitors and inductors, switched in and out of the circuit by relays under microprocessor control. A built-in SWR sensor provides feedback; the microprocessor searches the capacitor and inductor banks, seeking the lowest possible SWR.
The tuner is a “Switched L” network consisting of series inductors and parallel capacitors. LDG chose the L network for its minimum number of parts and its ability to tune unbalanced loads, such as coax-fed dipoles, verticals, Yagis; in fact, virtually any coax-fed antenna.
Using seven toroidal inductors, the total inductance ranges from 0 to 10 μH. Each inductor’s value is selected to provide 128 different combinations, with a resolution of 0.08 μH. The inductors are switched in and out of the circuit by relays controlled by the microprocessor. An additional relay switches between high and low impedance ranges.
Features
– Automatically matches antennas from 6 – 800 ohms impedance, or a 10:1 SWR
– Handles 1000 watts output on SSB, 750 watts CW and 500 watts on FM, digital or other 100%
duty cycle modes
– Tunes in less than 10 seconds, usually less than 5 seconds
– Retains last tuned setting as long as DC power is connected
Specifications
– Impedance range: 6 – 800 ohms, or SWR up to 10:1
– Minimum power for tuning: 20 watts
– Maximum power while tuning: 100 watts with rollback, 20 watts without rollback
– RF power limits: 1,000 watts SSB, 750 watts CW, 500 watts “key down”, FM, digital or any other 100 % duty cycle mode
– Meter accuracy: +/- 5% of full scale across entire range
Microprocessor: 68HC11
Power requirement: 11 – 15 volts DC, 2.5 x 5.5 mm coaxial plug, center pin (red lead) positive
– Current consumption: 1 Amp or less
