Japan Radio Company Ltd., Tokyo
NRD - 515
überarbeitet am 19.10.2010
As a company with a very good reputation for maritime communications equipment, the Japan Radio Company brought out their first affordable shortwave receiver aimed at the amateur radio market in 1977, the NRD-505. It's successor was the NRD-515, the first JRC receiver that went into mass production. It was an absolute success as fas as it's design, it's straightforward operation scheme and it's shortwave reception performance are concerned.
The NRD-515 is a medium sized (340 x 140 (with memory unit 190) x 300 mm and 7,5 kg) semiprofessional desktop receiver, JRC kept it's dimensions for all later sets. The matching speaker NVA-515 came with the same height (140 x 140 x 300 mm), the NSD-505 is the matching amateur radio transmitter. The set is mains powered and can be set to 117 or 220 V mains operation.
The front panel is grey / anthracite coloured; at it's left side, You find
a big rotary knob to select one of the thirty 1 MHz segments and the main tuning
knob. For faster tuning, You preferably use the UP/DOWN switch, as the main
tuning knob gives You only 10 kHz frequency chance per revolution. A small LOCK
switch will lock the main tuning knob, all impulses are electronically sent to
the receivers PLL circuitry.
After the attenuator circuit, the RF signal has to pass a 1.6 MHz high pass filter and a 35 MHz low pass filter active in the shortwave bands. In the first mixer, it is converted to the high first IF of 70,455 MHz and after an IF amplifier stage it is mixed to the second IF of 455 kHz commonly found in commercial shortwave receivers. In the stage, the signal will have to pass the Noise Blanker and IF filter bank, and will reach the demodulator after another amplifier stage. The set uses an internal PLL frequency synthesizer, as an alternative to the main tuning control, the receiver can be controlled from an optional external memory expansion or the pocket calculator - like external frequency controller NCM-515.
The receiver has been appointed receiver reference, when it came out, and
I'm still enthousiastic about it thirty years later. The NRD-515's sensitivity
is excellent and You can make full profit out of it, as the set performs
free from unwanted signals thanks to it's high first intermediate frequency.
The selectivity is acceptable if You use the ceramic 6 kHz IF filter within
a broadcast band, the real thing is ECSS reception using the mechanical 2.4
kHz IF filter which is switched in only in SSB mode. Use the Passband Tuning
to eliminate an unwanted interfering carrier from an adjacent channel, the set
comes without a Notch filter.
© Martin Bösch 25.7.1999