Note
Ham Radio, Feb 1971, p. 74.
National's HRO- 600 communications receiver was a high-performance, solid-state receiver. The "systems" concept allowed a user to custom-tailor a receiver to their specific needs at the lowest cost consistent with their requirements.
The HRO-600 receiving system consists of a main frame, choice of three frequency control plug-ins, and a selection of accessories. The main frame contains all receiver signal path circuits from antenna inputs through line and speaker audio outputs.
These circuits include an antenna attenuator, slot filter assemblies, frequency converters, IF amplifiers, IF filters, AM and product detectors, and audio amplifiers. It also includes a frequency synthesizer for first mixer injection, a BFO, and a 115–230 volt 47–420 Hz power supply.
When the main frame is augmented by one of the frequency-control plugins, the receiver is capable of operating at any frequency between 10 kHz and 30 MHz. Modes include AM CW, SSB, FSK and FAX. FSK operation requires an accessory plug-in FSK converter or external audio equipment. FAX reception requires external audio equipment.
Other accessories available for the NRCl HRO-600 include a noise blanker, diversity combiner, remote-control system, DC power supply, VLF/MF/HF preselector, and independent sideband adapter.
References
Brief description. Ham Radio, Feb 1971, p. 74.