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Japan Radio Company Ltd., Tokyo

NRD - 505

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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.

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<4 uV, SSB<2 uV,
2 - 30 MHz AM<0,5 uV, SSB <0,3 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

4 memories optional

The NRD-505 is a medium sized (340 x 140 x 300 mm and 10 kg) semiprofessional desktop receiver, JRC kept it's dimensions for all later sets. 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. Two knobs will control the RF and AF gain / volume.
In the middle of the front panel, You find the large frequency display with red glowing LEDs; in a red backlit window above the main tuning knob, You will find also a mechanical frequency dial with an accuracy of better then 1 kHz.
In the right part of the front panel, You find two rows of buttons and four rotary knobs. In the top row, You find the manual / preset selector, four pushbuttons to recall four frequencies from the receivers memory (memory was expensive in those days) and a MEMORY button to store them.
Just below, You find the switches for an external VFO, the DeltaF tuning (or receiver incremental tuning), the noise blanker, attenuator and the mains switch.
The four rotary controla operate the DeltaF / receiver incremental tuning to move the reception frequency a bit up or down from a stored frequency (useful if You use a radioteletype converter), the BFO, the reception modes switch and the two speed AGC switch. The reception modes switch selects also the narrow and wide AM bandwidth, the narrow CW bandwidth can only be used, if the optional narrow CW filter is installed.

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 receiver has got enthousiastic reviews when it appeared in 1977 as the first JRC radio aimed at the amateur radio market. Undersome conditions, it has been outperformed by a Sony ICF-6800W or another amateur grade receiver with an internal telescopic antenna, just to find out: this set really needs a good antenna to give You the results You expect from a semiprofessional set. The NRD-505's sensitivity is excellent and with a matching antenna, 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 also great when You switch from the 6/10 kHz ceramic AM filter CLFD6S to the AM-narrow / SSB / CW-wide filter: this real gem is a 2,2/4 kHz mechanical filter, the same with the optional mechanical 0,6/2,3 kHz CW-narrow filter!

The Japan Radio Corp. NRD-505 is an absolute classic among the semiprofessional shortwave receivers, as it's price tag was much higher then the one on the NRD-515 and the NRD-525, it is not so common on the used receiver market. If You can find one, You get a set that You can enjoy on the bands for all purposes of broadcast or amateur radio DXing without an investment in filter modifications, but it's worth to check whether the 4 frequency memory option is installed.

further reading:
d / e: JRC NRD-505 at www.radiomuseum.org
d: NRD - 505, 10 kg Technik mit Kurzzeitgedächtnis, Bernd Ehlers, addx kurier
d: Testbericht NRD - 505, Rainer Lichte, addx
d: Verlgeichstest NRD - 505 und AOR 7030, Dieter Schäfer, addx
d: NRD - 505 der 1. "Preiswerte" von Japan Radio Company, Nils Schiffhauer, Oldie KW-Empfänger

© Martin Bösch 4.7.2010