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N9EWO Review :
Japan Radio Co. JRC
NRD-93 HF Receiver

(JRC) Japan Radio Co. NRD-93 HF Receiver

Discontinued Receiver

(This light review is from 1998 and has been edited from that version)

Solid Construction / 5 Volt Switching Power Supply / Pass Band Shift / Sensitivity Very Good

The JRC NRD-93 has not been sold new since 1995. Audio quality is MUCH improved over "any" other JRC receiver that I have owned before (except for the NRD-545). The sound is sharper, clearer and the AGC works good (in fast only, see text below). No "woolly" sounds, or hiss coming out of this set. Construction innards are similar to the NRD-525 , except there are no surface mount parts that I could see ? Unlike the model that followed (the NRD-240) the 93 does indeed have Pass Band Tuning.

Unit runs pretty cool, a bit more heat comes from it's 5v switching power supply (did I say switching supply..yes I sure did), but is more on the warm side than hot. The "Dimmer" is a control and not a bloody 2 or 3 step button, a big plus. The LED's are much easier on the ole' eye balls. All the controls have a excellent feel, no wobbly knobs. All pot's are above average (sealed) quality...not the usual consumer grade. Even the metal plate that contains the serial number is impressive.

The speaker arrangement is a bit different from what we "consumer's" are used to. The speaker audio output is at 600 ohms (1 Watt). Jack is in the front for the included externa; speaker, 600 ohm output. This speaker is a 8 ohm, but with a 600 to 8 ohm transformer inside. There is actually a 4 ohm output on the rear connector, but still uses a internal audio transformer. Even the audio "Line" output is isolated with a 600-600 ohm transformer.

The "PBS" (Pass Band Shift) works great. Overall sensitivity while very good is no barn burner. Most more modern JRC sets (say the NRD-545) will give for better performance in the deep down "in the mud signal" capture. Stable as a rock. When you get the receiver and the optional NDH-93 memory unit all placed in the cabinets the weight gets very close to 45 lbs....huffda.

LED Display Noise

The NRD-93 has a sound that I have never heard emitting from a radio. It’s a very high pitched whine. It will get louder as you turn up the LED display brightness control. This sound seems to be coming from the power supply part of the set ? This also is where part of the circuit is for the LED brightness control is as well. JRC continued to use a similar circuit in the NRD-301A as it too whines the same way, and increases in pitch and volume as you push the Dim "button". This seems to bother some people but not others, depending how good your hearing is. It drove me up the wall, and was one of the main reasons why I did not keep my NRD-93. This whine never enters into the receiver or audio chain of the radio, but it sure does fill the room up with this sound of those who can detect it.

Limited Voice Bandwidths / Non JRC Filters A Pain To Make Work

IF bandwidth filter arrangement for voice modes is not perfect for broadcast voice use. You have either a 3 or 6 khz as it came new. As usual for me the 6 khz was a bit too narrow for my tastes. Thank goodness I still had around a 8 khz filter that I had pulled from my old "early version" NRD-535 that fit the bill real well. From information that I received via Rob Sherwood (Sherwood Engineering), you have to be careful installing filters in a JRC receiver. JRC filters use a 600 ohm impedence (termination). Most other filters including the ones that he sells are around 2000 ohms. No cigar if this is not met. You can modify most JRC radio's to work with other voice bandwidth filters from other sources. JRC never offered any optional voice filters. I was not up to sending if off to have any mods done and the 8 khz (perhaps closer to 10 ??) filter worked good for me. I cannot help it, I like the wider filters. I used manual ECSS with the 3 Khz filter for the trouble spots on the dial.

To the left of the main display (green) indicates in Khz the BFO/Clarfier adjustment made, to the left indicates the PBS (Pass Band Shift) adjustment in Khz. Each of the NDH-93 Memory unit channels store the Frequency, Mode and the Bandwidth. Not bad as the older NDH-515 (memory unit for NRD-515) only stored frequency.

Nice S-Meter, But Not Lit / Sherwood SE-3 a No Go

Unlike the NRD-525-535 and even with JRC's NRD-545, the 93 has a good old standard S-Meter. I have yet to see it pin, and is very useful. However , it lacks proper markings, also it takes a pretty strong signal to make it start to read . It also doubles as a "line level" audio indicator as well, but I found it to read WAY low.

Rear panel has BNC jacks for a external 10 MHz reference, and a 455 kHz IF output. The Sherwood SE-3 "Sync" detector will work right out of the box with this set (using the IF Output) ??

However we tried a Sherwood SE-3 external Sync with the NRD-93....and FORGET IT ! It did not interface well. Audio distortion at ANY IF level adjustment. I got much better just audio using manual ECSS tuning with the wide filter..MUCH better in fact. So forget the SE-3 with the NRD-93 ! To be fair, let me say that it did help with the fading distortion very much. However the overall audio quality that was being heard from the speaker and even more so from the "Record Output" of the SE-3, was distorted and buzzy, it did not sound overdriven either. The overall audio comming from the NRD-93 without the SE-3 actually sounds better. "MAYBE" some tinkering with the IF level inside the 93 would have helped, or maybe another buffering stage {maybe not ??}???, but I'm not about to play with the way !! So was better without it.

Strange AC Power Input Plug / Grounding The Set is a Must / Changing AC Input Voltage is Hard Wired

The AC power input is strange. They are using a oversized 2-pin Microphone connector. Take a standard 4-Pin CB mic connector..make it 2 pins centered in the middle, and a bit larger and that is about it. From what I have been able to find out from others, JRC used this as it was a standard on some other marine radar system(s) ?? You have to make sure that the set is well grounded, as the case carries at bit of a potential (can give you a nasty buzz on your skin). I just used a 3 wire power plug/cord and this problem goes away 100%. I have talked to others who have owned NRD-92's and 93's and all have experenced this same little gremlin. So if you ever get hold of one of these..Ground the case it BEFORE you plug it in !!

This is caused by 2 disc ceramic capacitors connected across the rear of the AC input socket inside the set and those are connected to ground (case) of the set.

If you need to change the AC (mains) input voltage , this is done with hard wiring and not a switch. One will need a soldering iron to get the job done. The manual covers this information well.

Is It Perfect ?? / Audio Quality / Slooooooow AGC

At this point you are saying....for a professional receiver, it should be perfect ?? Well that would be nice..however there is no such a receiver on this planet that is and the 93 has it's share of bug-a-boo's. Remember that the 93 was on the drawing board in very early 80's.

It's synthesizer is relatively noisy. If you pull the antenna off and tune around the band, in certain areas (the 11 Mhz area is full of them) they show up. However this is not as bad as it seems. Just the noise in the band covers up most of these birdies. The NRD-535 has a much worse problem as far as noise goes.

Now you might be wondering..."does the NRD-93 audio sound as good as the AOR AR-7030" ?? Well that ones easy....NO WAY !! For AM mode broadcast stations, the audio is one of the best in a JRC product that I have ever used (up to the NRD-545 which was the best JRC receiver in my view for audio). SSB signals actually sound better on the NRD-93 vs the AR-7030. Cleaner, and less clipping distortion. If I used manual ECSS with the NRD-93 (which by the way works very good) the audio distortion is almost nil.

The AGC "Slow" decay rate is "way" too SLOOOooow. Matter of fact the slowest I have ever used with the expection of the EARLY Kenwood R-1000's , which is the all time slowest for me. If all signals are about the same strength, (let's say you are tuning in a number of Hams on one frequency), it's useable. But if you have one strong signal with a bunch of weak ones, you better switch it to fast or you will not hear any of the weak signals at all. Good news here is that the fast works well even on SSB signals. No excessive distortion. On certain broadcast signals the "Slow" setting can actually help iron out really deep fading distortion (but not always). It's not a major drawback.

Good or Bad ??

The NRD-93 is a fantasic piece of equipment. Built like a tank, ease of operation and performance is excellent. However these are "really" getting more rare and old on the used market, and those who have one usually hang on to them until they are cold in the ground. But once in great awhile one does surface. Used prices seem to be hitting the sky as well (no where but "up"). Also finding a sample that has not been aboard a boat or ship is a important point to concider.

Someting else to keep in mind. As is the case with most JRC receivers, the NRD-93 is full of mechnaical relays and in it's old age will require attention sooner of later.

Dave N9EWO
N9EWO, all rightrs reserved
Ver 9.0

Discontinued Receiver

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