Amateur and Shortwave Radio

Paul Lannuier

West, Texas • McLennan County
EM11kt • 31.80°N • 97.09°W
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Notes on the Japan Radio Co. NRD-535 HF Receiver (and other JRC models...)

JRC Brochure Archive

PDF copies of various JRC brochures from my collection (NRD-345 brochure courtesy N9EWO - tnx Dave!). Click on thumbnail to download.

NRD-505 NRD-515 NRD-525 NRD-535
NRD-545 NRD-345 JST-100


NRD-535 Receiver Design Concept Sketches

These artist concept images were sent to me by T. Shiono, head of the NRD-535 engineering team, shortly before I was scheduled to visit JRC's Mitaka factory for the design review meetings in June 1990. Click any image to enlarge.

I arrived in Tokyo armed with numerous ideas and opinions, including many from people in the SWL hobby such as Tom Sundstrom W2XQ, who was a big influence in improving the RS-232C interface command set from the prior model, the NRD-525.

After hammering out the desired feature set of the receiver, we met with the artists to review the concept drawings . It was decided that a combination of the dimpled arrow buttons from A and the control layout and contoured front panel of B would be ideal, with a few tweaks here and there with respect to control placement. I recall arguing strongly against the front panel speakers of C and D. The curved s-meter LCD segments of the final design were added after my return to New York.

JRC IF Filter Designators

JRC's optional crystal IF filters were sourced from NDK and did not have the JRC "CFL-xxx" designator marked on them. Use the following cross-reference chart to help identify wich crystal filters are installed in a JRC radio. I don't have the NDK "YF" numbers for the two optional CW filters (300 and 600 Hz) that were available for older radios like the NRD-515 and JST-100; if anyone has this info, please email me and I will update the chart.



-6dB Width



240 Hz



300 Hz



500 Hz



600 Hz



1.0 kHz



1.8 kHz



2.4 kHz


Nice Ass (Button)!

One of the more humorous episodes to occur during the NRD-535 design review meetings at JRC was the now-infamous saga of the ASS Button. In 1990 the then-current marine/GMDSS HF receiver, model NRD-240, had an interesting function called "Automatic Scan Start", enabled by pressing a front panel button labeled "ASS". This had already been the source of great amusement at SWL festivals where I distributed brochures on the NRD-240, not to mention the endless ribbing I endured by attendees at the Dayton HamVention where we had the '240 on display.

Now, as the NRD-535 was being conceived, the ASS button made it's way into the discussions. As the only person at the meetings whose first language was English, I felt it was my responsibility to make them understand the marketing implications of having the word "ASS" appear prominently on the front panel. This involved a combination of spoken word and insane hand gestures, with some translation help from Shiono-san. It was bad enough that they used the prefix "NFG" to denote the JRC line of antenna tuners. "Please," I begged them, "don't make me market a product with an ass button!" A moment of silence was quickly followed by an eruption of laughter as it finally became clear to the group what my fuss was all about. The ASS button was scrapped, thankfully.

NRD-535D IF Filter, BWC and Firmware Upgrades (or: What's an NRD-535Db?)

The NRD-535D (the "D" model included ECSS, BWC and 1 kHz crystal filter options factory-installed) was released in the North America market in 1991 - I don't recall the exact date of first delivery but my records show that orders were being accepted in January 1991. In short time it became obvious that certain modifications were necessary, most notably:

  • Variable Bandwidth Control (BWC): Originally designed for the JST-135 transceiver, it only worked in SSB/RTTY/CW modes and only with the intermediate (2.2 kHz) mechanical filter. It needed to be enabled in AM mode and made to work with the wide filter.

  • Wide Filter: The standard Murata CLF-D6 filter (around 8 kHz @ -6dB) was a step backwards from the CLF-D6S which was used in the NRD-525 and earlier JRC receivers which was spec'd at 5.7 kHz @ -6dB (8.7 kHz @ -60dB); . The '535 needed to switch back to the D6S.

  • Computer Interface: Some commands behaved badly, others needed to be added to keep the software developers here in the States happy.

At my urging the factory incorporated these changes into production runs starting with NRD-535 serial no. BR56005. To differentiate this improved model from older units, Dick Robinson at Electronic Equipment Bank (Vienna, VA) decided to add the "b" designator in his ads and catalog listings for the NRD-535D. It was never an official JRC designation, but the terminology was adopted by NRD-535D users and continues to this day on various JRC-related reflectors and online groups.

Owners of NRD-535D receivers older than BR56005 were offered an upgrade kit which included a CLF-D6S filter, a new crystal filter for the CLF-243 BWC board, and a new set of EPROMs (version "D") updated the receivers firmware to enable the BWC to work correctly in AM mode and with the CLF-D6S and included several bug fixes, and implemented several fixes and additions to the RS-232C interface command set.

The upgraded BWC board was designated CLF-243W ("W" for wide) in units with serial numbers BR56005 and later; the easiest way to tell if an original NRD-535D has been upgraded is to simply see if the BWC works with the wide filter in the AM mode; if it does, then the upgrade kit was installed. I am not sure whether JRC still offers the NRD-535 upgrade kit; I suggest contacting Universal Radio in Ohio for further info.


I've received a couple of emails about this in the past and I've seen the question posed on some of the receiver forums, so I thought it would be useful to lay out the definitive answer to the question, "What is an NRD-535GS?"

The '535GS, sold by Gilfer between 1995 and 1997, was a standard NRD-535 (non-D model, without BWC, ECSS and 1 kHz crystal filter) that was enhanced for shortwave broadcast DXing. Here is the description from the old Gilfer web site:

The NRD-535GS was developed by Gilfer Shortwave for the serious shortwave broadcast DXer. While the stock NRD-535 and NRD-535D receivers are already excellent performers, we have taken the basic NRD-535 design a step further, improving several critical perfomance characteristics to create the ultimate SWBC DX machine!

I.F. FILTER SELECTIVITY - To compliment the standard 6.0 kHz wide AM filter, a custom 3.5 kHz ceramic filter specially designed by Kiwa Electronics for the NRD-535GS is installed in the intermediate filter position, in place of the stock 2.2 kHz filter. For SSB, JRC's 2.4 kHz crystal filter (CFL-251) is installed in the narrow filter position. In the aux position, we will install your choice of JRC crystal filter: 300 Hz (CFL-231), 500 Hz (CFL-232), 1.0 kHz (CFL-233) or 1.8 kHz (CFL-218A). Finally, a rear-panel toggle switch is installed to give users the ability to bypass the aux filter stage entirely, using only the receiver's 12 kHz. This delivers the widest audio for pleasurable program listening.

AGC PERFORMANCE - We modify the automatic gain circuit to increase the decay speed. This reduces the AGC "hang time" in both fast and slow AGC settings.

AUDIO QUALITY - The high audio cutoff frequency is raised for brighter sound quality, especially when the IF filters are bypassed for local station listening!

SYNCHRONOUS ECSS (optional) - Add JRC's optional ECSS unit (CMF-78) for outstanding phase-lock synchronous AM detection with independent selectable sideband operation.

Other options include the CGD-135 High Stability Crystal Kit, NVA-319 External Speaker and CMH-530 RTTY Demodulator.

Each custom NRD-535GS receives a complete bench-check and frequency alignment before shipment. Gilfer warranties the NRD-535GS for a one-year period (parts and labor)

When ordering the NRD-535GS receiver, please be sure to specify exact filter and ECSS configuration.

The NRD-535GS sold for $1,659.95; it was available with optional ECSS unit for $1,869.95. I don't remember how many were sold, probably only a few dozen. The "NRD-535GS" should not be confused with the "NRD-535G" - the latter was simply the European verision (factory pre-set to 220V and supp[lied with Euro power cord); JRC used the "G" suffix on several models as a designator for Europe, while "U" designated North America. These designators are only marked on the carton, not on the radio itself.

Disclaimer: Why am I doing this?

I receive fairly regular emails out of the blue from SWLs and hams who own JRC receivers and transceivers, asking for info that I might be able to share with them. Some of them know and remember me from the old days when I was a sales manager for JRC's New York office, others find me by Googling or whatever. Now, as then, I am happy to help however I can, although my contacts at JRC have been severed and my memory is rapidly failing. Therefore, I have created this page to post some of my thoughts and recollections of my time with JRC and my small part in bringing the NRD-535 receiver, JST-245 transceiver, and JRL_2000F to market in North America. I welcome comments and additional info from JRC enthusiasts, but please keep in mind that I no longer represent Japan Radio Co., Ltd. in any capacity, and that any interest I have in JRC amateur and SWL products is purely that of a fellow enthusiast and ham. Any opinions stated or implied are solely my own and most likely do not reflect those of Japan Radio Co., Ltd.

©2013 Paul Lannuier WW2PT