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Japan Radio Company Ltd., Tokyo

NRD - 535

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überarbeitet am 19.10.2010

Five years after the introduction of their very popular NRD-525 receiver, the Japan Radio Company brought out a successor called NRD-535. It features continuous bandwidth control and an improved synchroneous demodulator.
Take care of the various receiver variants: only the NRD-535D (US version, golden model number lettering) and NRD-535DG (European version) are equipped with the ECSS board, the BAdnwidth Control board and the narrow 1 kHz filter. In early sets up to Serial No. 56005, variable bandwidth control BWC is only active with the INTERmediate filter in SSB operation.

Tripe conversion, IF 70,455 MHz, 455 kHz, 97 kHz

Digital frequency display , 10 Hz resolution, coverage 100 kHz - 30 MHz

AM, AM-Sync. optional, CW, USB/LSB, RTTY, FM-n

Sensitivity 100 kHz - 500 kHz AM<15,8uV, SSB<5uV, 500 kHz - 1,6 MHz AM<6,3uV, SSB<2uV,
1,6 - 30 MHz AM<2uV, SSB <0,32 uV, FM<0,5uV

Selectivity -6/-60 dB
AM wide 6/15 kHz, inter 2/6 kHz, narrow* 1/3 kHz, aux/FM 12 kHz & variable IF bandwidth

S-Meter, RF-Gain, three AGC speeds, Pass Band Tuning, Noise blanker, Notch Filter

200 memories, Scan modes, Clock / Timer, integrated RS-232 interface.

The NRD-535 has the same dimensions as it's predecessors (33o x 130 x 287 mm, 9 kg), it's anthracite front panel colour and the arrangement of the front panel controls have been kept from the older model, but the design has been improved with rounded pushbuttons and more elegant knobs.
The receiver can be powered from 100 - 240 V mains or 12 - 16 V DC for mobile operation onboard vehicles or boats. A tiny monitor speaker allows You to control the cerroct function of the set, for pleasant listening, You have to connect an external speaker or decent headphones. JRC had not only the simple NVA-88 speaker but also a high tech speaker with integrated audio filtering, the NVA-319, in their catalogue.

JRC did slightly rearrange the controls on the front panel, they moved the three positions mains switch the the left side of the receiver. In the right lower corner, You find the volume and tone control. The numbered keys for direct keypad frequency entry are still in the same position as in the earlier model, You still risk "NRD users wrist cramps"... (I know, You can get pain from using Drake's R-8 keys too, but these pain has a different location). Six pushbuttons above the big main tuning knob alter the function of the two big UP and DOWN buttons. Their function is indicated by small green LEDs in the buttons, You can set the UP / DOWN buttons to control frequency, IF bandwidth, AGC speed, tuning steps and tuning speed and You can activate ECSS operation.
Siy rotary controls in the left lower part of the front panel are used to control RF gain, the Notch filter to eliminate an interfering carrier's signal, the Squelch circuit, the Passband tuning to shift the IF filter bassband to the less disturbed side of the signal, the variable bandwidth control and the Noise blanker activity.
As a reaction to complaints from confused users, JRC added a small red indicator to keep You informed that ATTenuator, PBS, NOTCH are active, to the main display.
It is very helpful that JRC renounced using concentric knobs and double functions of the rotary controls. Six pushbuttons just below the frequency display give You direct access to the different reception modes, all of these have a second function for scanning modes, etc. not so often used.
JRCs engineers did not follow all complaints about the multicoloured fluorescent display: the 535's S-meter is still a restless yellow line or yellow bar, the big bright blue digits will indicate either reception frequency or the time, but not both at a time. The memory channel numbers and the indicators for activated reception modes, bandwidth, AGC speed and so on, are much smaller. But You can finally rely on the fact, that with the S meter line most lefthand on no red indicator on, the set should perform normally, You should hear some slight background hiss.

The rear is very similar to the one of the NRD-525, only the model designation and the missing VHF/UHF connectors will tell You, You are sitting behind a '535. You can switch the antenna connector from high impedance long wire to low impedance coaxial socket.

An incoming RF signal will pass a 35 MHz low pass filter and the switchable -20 dB attenuator; an electronic preselector will let pass only the desired reception frequencies. After a RF amplifier stage, the signal is mixed to the high first IF of 70,455 MHz, after a next IF amplifier stage, it will be converted to the second IF of 455 kHz. In this stage, the Noise Blanker and the switchable IF bandwidth filters as well as the variable bandwidth control circuitry are active. After another conversion to a third IF of 97 kHz, the signal has to pass the electronic notch filter and the passband tuning, the filter passband can be shiffted to one side to let pass only the less distorted half of the signal, and the synchroneous demodulator for automated ECSS reception, the signal is demodulated and will reach the listeners ears...
All frequency synthesis takes place on the main processor board, the oscillator frequencies are generated in a low noise PLL circuit with an accuracy of 1 Hz.
An RS-232 interface is already integrated in the receiver, an optional RTTY decoder board can be plugged in, but there is no option to install an internal VHF or UHF converter.

In practical use, the NRD-535 performs at least as well or even better then it's predecessors. It has a high sensitivity, thanks to the high first IF, spurious signals and intermodulation effects are very rare, as are "birdies" the internal processor. The dynamic range is wide, the NRD-535 performs quite well with improvised randem wire antennas, but even long long wire antennas or dipoles will not cause overloading.
The capabilities of RF signal processing are excellent, You have several different options to reject an unwanted interfering signal. In early sets, the skirt selectivity of the standard filters has caused complaints, the filters in the G version perform well, the filter skirts with activated bandwidth control seem not to be very steep, so the audio with bandwidth reduced th 2 kHz sound not as crisp as with the Collins mechanical 2 kHz filter. The high frequency hiss from the internal synthesizer has been reduced nicely.
The ECSS mode with selectable sidebands, in this mode, an internally generated carrier is added automatically to the received sideband, is a useful tool to improve readability - signal strength is not subjugated to carrier fading anymore. TBe careful with tuning the PBS and BWC, every time, the ECSS looses synchronisation, You will hear a howling noise.

The NRD-535 is an excellent allround receiver suitable for broadcast DXing as well as CW and radioteletype reception for the Utility DXer. The set has been several test team's reference set, before the DSP receivers NRD-545 and Watkins Johnson HF-1000 made their appearence on the market.
So it was possible to buy a NRD-535 in good condition second hand after the introduction of DSP receiver technology for a reasonable price. You should make sure that You are looking for the right version before You bid on an eBay offer. Usually in Seitzweland, prices are much better then in Germany, as the German importer made a very good profit just for adding a German language translation of the Owners manual.

It was not a difficult task to prepare a serial cable to connect my PC with the NRD-535's RS-232 socket, after I had found the informations about the pins in the manual. You can control the rig from a Windows terminal programme, I did use the SMART NRD Control from Mark Fine, there are several other rig control programmes available.

further reading:
d / e: JRC NRD-535 at www.radiomuseum.org
d: JRC NRD-535 DG - der Beste?; Ch. Ratzer, weltweit hören 11/92
d: NRD-535 G von JRC; kurier 8/91
e: the JRC NRD-535; Bob Evans, fine tuning's proceedings
e: comparing the Drake R-8 and the JRC NRD-535; John Bryant, fine tuning's proceedings

© Martin Bösch 25.7.1999