receivers dating back to the original model that have been restored by vintage amateur radio enthusiasts and other hobbyists. See also ARC-5 ART 13 transmitter BC-348 BC-654 Hammarlund super pro R-390A References External links The Evolution of the National HRO and Its Contribution to Winning World War II HRO receiver HRO receiver models National Radio product line A brief history of the National Company, Inc. Originally published in The AWA Review (Vol 1 1986) National Radio with HRO details Dating The Early HRO, Antique Wireless Association Radiofrequency receivers Amateur radio receivers Military radio systems of the United States World War II American electronics Equipment of the United States Navy Military equipment introduced in the 1930s