Note
QST, Aug 1947, inside back cover.
Concord catalog 9-47, p. 160.
Allied catalog 1948, p. 155.
Lafayette catalog number 89, p 175.
See National's Notes: QST, May 1949, p. 59.
Lafayette-Concord (1949 #949), p. 144.
QST, Sep 1951, p. 117. ("while they last"}
Even though the HR0-7 shed the basic black livery of its predecessors and acquired a sleeker cabinet, inside it was still cast in the mold of earlier HROs. It had plug-in coils, and frequency readout was interpolated from the PW dial and a scale attached to each coil. Standard HRO practice was also followed with the external power supply. Nine sets of coils covered 50 to 430 kHz and 480 kHz to 35 MHz. The 12-tube HR0-7 improved upon previous HRO designs with the addition of a voltage regulator tube for the HF oscillator B+ and a more effective noise limiter.
