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Japan Radio Co. JRC
NRD-630 DSP HF Receiver


JRC's Last (HF) Receiver , the NRD-630.
DSP based yes, one of JRC's best....NO !!!
(Photo : N9EWO)


(I do not own JRC NRD-630. A borrowed sample was used for this report)

Firmware/Software on tested sample : 1.4 1.1

(This is how it was displayed). I believe the 1.4 is for the DSP and the 1.1 is the Operation Firmware ? I was able to see the sticker on the EPROM IC next to the DSP IC’s and was marked as 1.4 , I was unable to get easy access to the front panel to check the other 1.1 number out. )

Country of Manufacture : Japan

Discontinued Receiver


Very Limited Number Made. Only One Production Run ?? Price Varied Greatly (at least in the USA).

I don't have any solid information here, but from what I was told the NRD-630 was a "one production run" model. Price in the USA started out at $ 9000. USD, however it quickly dropped..

How many that were actually made is unknown, but if the single production run rumor is true, it sure can't be very many ? Good thing too as this JRC DSP set was nothing to get excited about as we will cover in this report below.

Excellent Construction But Not Using Mother Board Scheme , Direct Keyboard Entry With Excellent Keys, No Feet Included.

As is the tradition with Japan Radio products, the NRD-630 is beautifully constructed. Heavy gauge aluminum shell with 2 die cast rack handles. One major difference is that it is not using a customary mother board with side in computer style boards. Instead, it’s divided up between 4 PC boards of varying sizes mounted flat on the floor (or roof) of the set. 2 on the top (including the DSP/CPU board), the small main RF board on the bottom, and the much larger main microprocessor board on the front. Reminds one of the
JRC consumer NRD-345's board layout.

If one peers into the innards, it might be said “Where’s the Beef”? , as it’s DSP light with fewer components. It came in on our scale at only 12 lbs 10 oz (raw with no external cabinet). The entire RF section is on ONE small PC board, and that includes the "front end" preselection filtering too.

However, there are no “spaghetti” bowl of wires to be found either.


The 3 main NRD-630 PC Boards. The entire RF Unit is on ONE Small Board (right).
You can clearly see the 2 DSP IC's (DSP Board "left lower" picture).
(Photo's : N9EWO)

Can be disassembled in seconds too with only 4 screws holding the top and another 4 for the bottom. Just 4 more to remove the front panel from the main body.

If one does not use a additional outer cabinet with the receiver, the owner will have to add some large stick on feet as the raw cabinet does not provide any at all. With the 4 bottom cabinet screws this will be a requirement.

There is a excellent and very quiet switching power supply inside the receiver as well. This not some aftermarket supply JRC found laying around either. It’s custom made by a JRC sub-division (
Nagano Japan Radio Co. Ltd.). Even the potentiometers are top drawer using “Tokyo Cosmos Electric” controls.

All keys have a very good feel and are similar to ones found on preceding JRC professional models (NRD-240, NRD-301A etc). These are not of the “tac switch” membrane variety used with consumer equipment, so should be robust. They do not have a real distinctive tactile feedback however.

Direct frequency entry with the keyboard can be entered in MHz with the decimal or just as kHz without. JRC always does this right here and with the NRD-630 is no exception.

Oddly there are 2 unmarked dormant buttons found on the front panel.

It appears that the memories are non volatile, that is not being back by a battery of some kind (could not verify this) ?

Intermittent Operation With Keyboard Use In Testing.

In testing we did experienced a strange drop out issue.

Using keyboard entry (right after we hit enter) , intermittently the receiver would go totally silent. , along with the s-meter going to almost full scale.

Was like the RF gain control was turned fully counterclockwise (but it wasn’t).

Once we keyed in another frequency it would come back to life as well as the meter.

Again it only did this very intermittently, but this is inexcusable for a close to a $ 9000. professional set.

Very Good Ergonomics and Tuning Knob (Optical) , Channel/MHz Knob Not Quite As Good Feeling, Good PBT, But No Easy Center “O”, Notch Filter MIA. “Fiddly” Controls;

Ergonomics are almost at the top of the heap as there are a few minor bugs that lurk. Some of the controls are touchy and become a chore to use. For example, the PBT control has no center dimple on it’s control. One has to watch a LED until it shuts off. This is a very touch control and can easily be accidentally left on.

The RIT is another one that is sensitive to use. The RIT is adjustable 200 kHz from the tuned frequency, and is toggled on or off by single button with a led to indicated that it is in use, this is adjusted using the main tuning knob. There is no fast way to “zero” this one either, however it can be zeroed in the user defined functions, but is another chore here to make happen.

Weighted tuning knob uses a high quality optical encoder and is one smooth operator. But there is no mechanical resistance adjustment to help slow it down, so tends to be a bit too smooth. There are 8 tuning steps available with the tuning knob (1 , 10 , 100 Hz and 1 , 5 , 9 , 10 and 100 kHz) Up down slewing buttons just above the knob can be set to one of 4 steps (1, 5 , 9 or 10 kHz) located just above the main knob. You can also slow down the pulse rate of the main tuning knob encoder in the user defined functions and this helps with the overly aggressive speed, but not entirely.

One can be thankful that it does not use a even more touchy VRIT circuit.

The other larger knob just left of the main tuning is multi function, and again is used for a quick MHz adjustment, memory channel selection and also for selecting a group used with scanning functions, This encoder is not up to the main tuning knob’s quality, but is OK.

A lock button is provided, and in the user defined functions can be toggled to work just for the tuning knob or for all other buttons as well.

Where is the notch filter ? Another feature that found on
JRC consumer NRD-545 set but not on this $ 9K professional.

LED Display Top Drawer, 4 Level Dimmer, NRD-93 and NRD-301A’s Display Whine No Problem Here

Longevity is the name of the game here. The NRD-630 makes use of LED’s entirely. As we have said in years past, high quality and properly fed LED’s will outlast any LCD or Fluorescent device hands down. There is also a excellent 4 level dimmer. Well chosen steps, with one barely even detectable that’s it on at all.

The high pitched background display “whine” that plagued the
NRD-93, NRD-301A (and other JRC professional sets over the years) is totally absent on the 630.

Excellent Switching Power Supply, Cool Operation

As the comment was made above the NRD-630 uses a switching power supply, it has no power transformer. Mains power can be anything between 100 to 240 VAC (give or take a bit). No switches to fiddle with or fuse changes. Also one can power the set with 24 VDC. No 12~13.8 Volt DC input is provided, but being this is a professional receiver, this was not considered a drawback.

It’s clean too with no buzzes that consumer supplies commonly give out. The entire receiver runs cool as well.

Like many other professional receivers we see a sub-power switch on the rear panel. This needs to be turned on before the main power switch on the front becomes active. The LED in the main power switch changes from a dim to bright green between stand by to when the receiver is actually powered up.

Strange AC Power Input Jack Continues. Separate Input Fuses. Not UL listed.

Just as it was with the NRD-93 and NRD-301A we tested, the NRD-630 continues to use the weird AC and DC input power sockets/plugs. These are extremely solid and made by the highly respected Japanese company “
Hirose Electric” (HRS). They use a metal locking ring which provides accidental removal, but in a non professional environment setting, this will make a bit more difficult for a easy replacement of these cords.

With the tested sample that included a 117 VAC cord, it was only a 2 wire type. So if one desires a ground connection, there is large wing nut provided right next to the AC socket.

Another common trait with just about all JRC receivers, we could not find any UL or CSA listing marked on the rear panel. There are separate fuse sockets for the AC and DC inputs also found on the rear panel (see photo below).


Nagano Japan Radio Co. Ltd switching Power Supply (left), Hirose Electric "strange" AC and DC Power Inputs (right)
(Photo : N9EWO)

N Type Antenna Connector Being Used

The NRD-630 uses a N type antenna connector. While this may be a requirement for VHF and certainly in the UHF part of the spectrum, for a HF receiver this is downright weird. So most will have to purchase a adapter for conversion.

Unlike the older
NRD-301A sibling we tested years ago , the threads on this N connector were good.

Dual DSP IC’s, More advanced DSP Over The NRD-545. DSP Overloading Issues.

Two 32 bit “Analog Devices” DSP IC’s are being used in the NRD-630. These are a more advanced DSP IC’s that is
used in the NRD-545.

However, there are two DSP overloading issues that very disconcerting anyway.

The first one is similar to the NRD-545's DSP issues, but not quite.

During nighttime listening conditions with a good antenna (say 49 meter band at night, or any strong signal too even in the 19 mb during daytime conditions), we experienced a pulsing (popping sound) signal mixed with broadcast stations. In this case it does not pulse along with the audio stream. Can be with just a broadcaster with a dead carrier.

Difference here over the NRD-545 is that when the 10 db attenuator was engaged (with the pre-amp off) , this issue totally disappeared. In the case of the NRD-545, it does not cure the DSP overloading most of the time. So with the NRD-640 this is more controllable over the NRD-545, but should this DSP overloading really be there at all at almost $ 9K ?

Second DSP bug is much less important, but for the record. With extremely STRONG local MW signals, we noticed a stream of clicking-popping noises in step with the modulation of the signal. It is not like the NRD-545's overloading sounds.

This was only unearthed this in our extremely intense testing and really is small potatoes as this gremlin was not detected in any other part of the spectrum that it covers.

We were able to control this by switching off the pre-amp, or sometimes adding the 10 db attenuator. But of course this reduces the sensitivity too.

Sour Audio Quality, Harsh and Excessive Distortion with SSB Signals, Lousy Internal Speaker. No Synchronous Detection.

A major downside to the NRD-630 lies with audio distortion and quality in general. Yes, we have excellent audio recovery with it’s DSP. However it loaded with nasty distortion in SSB modes. This can be controlled by carefully decreasing the RF Gain control (and/or the attenuator). The ACG setting still needs to be in “slow” as well.

AM audio is no great shakes either. Additionally any static is downright painful to deal with.

A poor front facing internal speaker doesn’t help the sour pie. The use of a external speaker is a requirement and not a option. The rear mounted phone speaker jack uses a standard 1/4 inch type.

But even with a better external speaker in use , the audio quality is just downright tiring (narrow sound). It’s strictly flat communications quality that make’s for difficult any broadcast listening.

And yes, there is no Synchronous detection either (double or selectable sideband). So that cannot be of any help.

After about a 20 minute stint we had to turn this receiver off due to the painful audio (in any mode).


The Real Panel of the NRD-630, Uses a N type Antenna Connector
(Photo : N9EWO)

Digital Radiation

Here we find the self generated radiation to be is quite respectable. On SW is not noticeable at all unless you park another receiver right on top of the main LED display. And even here it is minimal.

On MW it’s touch more, but it’s not excessive either. Using a MW loop nearby should be no problem at all as long as it sits a foot or 2 away.

300 Memory Channels That Are Easy To Use, Scanning / Sweeping

For most applications the internal 300 memory channels are more than adequate. This is 100 more over the Ten Tec RX-340 and 200 over the WJ8711A.

Entry is super easy and access is done turning the left larger knob. This is excellent in use.

The old NDH-95 memory unit (designed in the 1980's) can also be connected to the NRD-630 as well (not tested).

Scanning up or down of the frequency spectrum or the memory channels are a dead ringer to the NRD-301A. Both work well.

Noise Blanker OK, But Not Adjustable

Noise blanker function while reducing local power line noise fairly well, has no other adjustments or settings. It’s either on or off and that’s it.

Excellent Sensitivity Performance With Pre Amp On, 2 Step Attenuator

As long as one leaves the 13 db pre-amp engaged, the sensitivity is excellent. If you operate it in the ruff with no pre-amp, it seems deaf (just like the Icom IC-R9500).

A 2 step attenuator at 10 and 20 db are provided and necessary too as covered above (DSP overloading).

Selectivity DSP Sharp, But Not Without A Serious Limitation

As far as DSP adjustability goes with professional receivers (or non professional for that matter), the NRD-630 falls flat on it’s face.

It’s sharp enough and does the job for taming adjacent signals. However, there are only 6 selectivity selections available and these cannot be changed or any additional added.

In reality there are only 4 that are useable with the lower 2 being useless CW bandwidths . The values are : 0.3 , 0.5 , 1.0 , 2.7 , 3.0 and 6.0 kHz. JRC’s lower cost
NRD-545 is much better here for versatility , and of course all other professional sets tested on this web site have a much improved arrangement for selectivity choices.

What happened here is a good question, it just simply is short of what it should be for a DSP based receiver.

AGC, Fast, Slow and Off, But “That’s All Folks”

3 AGC selections are available. FAST / SLOW plus OFF. The real down side is unlike all other professional sets tested, there is no other adjustment of the decay rate, etc. that can be done, at all.

It works well enough, however as cover elsewhere in this report, SSB signals are washed with distortion (even with Slow AGC properly selected) unless the touchy RF gain control is used.

Good S-Meter Performance, But Just Like on NRD-301A Is Non Illuminated And No Proper Calibration.

We have a excellent s-meter in the NRD-630. Never pins and is very linear. The only bug-a-boo that also has been the case with many other JRC professional sets (including the NRD-92/93, 240, 301A etc), is that the meter is not illuminated. A silly oversight as even a long lasting bright LED could have been used here which would have outlasted most other components.

Also continuing the tradition, there is no real calibration either. Just 0 to 10. One can alternatively select the meter to show the audio level of any given signal as well.

BITE Feature, Reset Button (Both Internal)

Many professional receivers offer “Built In Test Equipment” function or otherwise known as BITE. The NRD-630 provides this as well.

It’s not as handy as it could have been as one must remove the 4 top cover screws and press a small tac button on the DSP PC board to make happen. This is not covered in the instruction manual at all.

Once pressed with the receiver on, a series of numbers on the frequency display will appear followed by “good” if all is well.

Another internal button right next door to the BITE , is a “reset”. This does not clear any memory channels or “User Set Up” functions. It just helps one to get out of a locked up situation which thankfully we never encountered other than the intermittent “dead” mode as covered in the above text.

NOT the Best Choice In A Professional Receiver For Non Professional Use.

The NRD-630 is one extremely well made receiver. However with it’s limited DSP functions and lack of features surrounding this, it’s just does up not make up for the major downfalls. The nasty audio quality pretty much spoils the pudding to well steer to another model. Just about any of the other professional models tested here will more than likely be a better choice and maybe at a lower cost too. But it will be a hard find on the used market being very few were ever manufactured. This was JRC's last HF receiver and
NOT one of the best they produced in my view.

Dave N9EWO
N9EWO
Ver 2.2


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