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Japan Radio Company Ltd., Tokyo

NRD - 515

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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.

Double Conversion, 1st IF 70,455 MHz, 2nd IF 455 kHz

Digital frequency display, accuracy 100 Hz, coverage 100 kHz - 30 MHz.

AM, CW, USB/LSB

Sensitivity 100 kHz - 1,6 MHz AM<6uV, SSB<2uV,
1,6 - 30 MHz AM<2uV, SSB <0,5 uV

Selectivity -6/-60 dB
AM 4,5/10 kHz, SSB 2,2/4,5 kHz, CW (optional) 0,5/3 kHz

S-Meter, RF-Gain, two AGC speeds, Pass Band Tuning

24/96 Memories optional

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.
Two knobs at the left and the right of the main tuning knob will control the RF and AF gain / volume. Above the RF gain control, You find a knob acting as BFO control in the shortwave ranges and as preselector control on mediumwaves.
In the right lower corner, You find the switch to activate the AGC with fast and slow decay time and the reception MODEs switch. In the upper row, there are the Delta-F (corresponding to RIT / receiver incremental tuning, slightly shifting the reception frequency), the Passband Tuning (active in SSB modes only) and the bandwidth selector. In the standard version, the receiver comes only with the 2.4 and 6 kHz filters installed.
In the upper front panel parts, You find the analog signal strength meter, the red LED frequency display, indicator lights signalling external frequency control or Delta-F frequency shift, the switches for the noise blanker, two step attenuator and the mains switch.

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.
For broadcast band DXing, some users have had an optional 3 - 4 kHz filter installed, for CW reception, JRC had an optional 600 Hz filter for sale.
An optional external memory module has been extremely useful for storing 24 (NDH-515) or even 96 (NDH-518) frequencies. To use the external memory unit, the receiver has to be set to EXTernal VFO mode, the main tuning control will be inoperable then. So, there is no possibility to continue bandscanning from a stored frequency, You can only make fine adjustments using the Delta-F control (e.g. for CW or RTTY decoding). A very useful toll is the wired frequency control NCM-515, it looks like a big pocket calculator and gives You full control over the receivers VFO with direct frequency keypad entry and offers You four (!) memory channels.
Another option ist the Receiver control system PFC-100 made by the Swiss Poly Electronic Company: it offers You not only additional memory channels but also alphanumeric memory tagging. But these features usually found on modern sets did cost You the same amount of money as the complete NRD-515 receiver itself, so not too many of these control systems have been sold.

further reading:
d / e: JRC NRD-515 at www.radiomuseum.org
d: NRD - 515, ein Allbandempfänger der Spitzenklasse, Horst Marx, addx kurier
e: the Japan Radio Company's NRD-515, Kirk Allen, David Clark, fine tuning's proceedings

© Martin Bösch 25.7.1999