Bogen Challenger CHB 20A Vintage Tube-Powered PA (public address) Amplifier. Offered here is a Bogen Challenger CHB 20A Vintage Tube-Powered PA (public address) Amplifier. It comes with no other accessories or paperwork. We appreciate your business. In most cases these pieces come from surplus and business liquidation auctions and sales. We try to describe our items as best as possible and provide a number of quality photographs. We never intentionally sell broken items represented as working, and if we do sell you a broken item that we said worked, we will take it back. We take pride in our packaging and do a quality job of packing all of our items. We use quality new packing materials and boxes. Powered by SixBit’s eCommerce Solution.