National Horizon 20 HiFi Amplifier Manual Sorry, this product cannot be purchased. $8.99 Category: National Description Description For sale is reprint of National Horizon 20 HiFi Amplifier Manual. Manual is 8 pages Includes Part List and Circuit Diagram. Manual also includes 2 Service Bulletins Hi-Fi-8 and Hi-Fi-9 Related products National NC-57B NC57B Radio Receiver Manual $10.49 Read more National NCX-3 NCX3 HAM Transceiver Manual $9.99 Read more National NC-173 NC173 Radio Receiver Manual $10.49 Read more NATIONAL HRO Communication Receiver Manual $10.49 Read more