Ameco TPA Preamp / Indoor Active Antenna. Like-new condition, used only a few hours. $50 + shipping. The Ameco TPA is a dual-function device. It is a sophisticated preamp covering 220 kHz to 30 MHz with over 20 dB gain. The preamp features dual-gate FET circuitry and accepts input from a longwire, 300 ohm or random wire antennas. When an outdoor antenna is not available you can use the TPA as an indoor active antenna by extending the 30 inch built-in telescopic whip! Input from external antenna and output to the receiver is RCA phono jack.