Shortwave listening and everything radio including reviews, broadcasting, ham radio, field operation, DXing, maker kits, travel, emergency gear, events, and more
“It’s a great radio with top FM, AM, and speaker sound. It blows away my C.Crane Radio-2E. Lack of illumination, however, makes it less than ideal as a bedside clock radio.”
National RF, of California, has introduced a new “semi-kit” receiver: the RF 75-NS-3. Here’s an excerpt from the product description page of the National RF website:
National RF’s 75-NS-3 receiver is a complete super-hetrodyne mini high frequency receiver, designed specifically for the short-wave listener, electronics enthusiast or radio amateur, who wants to use their hands and build a radio. The receiver is offered as a semi-kit in which the electronic assembly is loaded and functionally tested at the National RF facility. The customer must then go to the grocery store (yes…the grocery store!), procure a can of [Spam] lunch meat, eat it or give it to the dog, and then proceed to drill and paint the can, in order for it to become the receiver’s enclosure! […] Detailed drilling instructions and final assembly instructions are provided as part of the kit. All other parts required for completion of the receiver are provided as well. Recognizing that the finished assembly looked somewhat like the fabled Collins receiver of the ‘60s, the 75S-3, (particularly when the can is painted a light gray) National RF engineers dubbed it (with tongue firmly planted in cheek, of course) the 75-NS-3! Although we have had fun packaging this receiver in a lunch meat can, it is nothing to turn your nose at! Its performance and portability will surprise you, and it is an ideal radio to bring with you on any trip!
The receiver architecture is that of a single conversion super-hetrodyne receiver, that is capable of receiving AM, SSB, or CW. The receiver incorporates a dual gate FET as an RF amplifier with manual peaking and gain controls. A ceramic filter is used in the IF section with a front panel switch that controls a broad or narrow IF response. Other front panel controls include audio drive, BFO setting, and a band switch for the HF bands. The 75-NS-3 has internal receive frequency coils that are switched at the front and rear panels. The frequency range of the receiver, over three band set positions, is 3.5 through 12 MHz. This allows reception of several international short-wave bands, the 80, 60, 40, and 30 meter amateur radio bands, and of course, WWV time and frequency standard stations at 5 and 10 MHz.
For those who simply want a lower cost receiver to monitor the shortwave frequencies, National RF offers two variants of the original receiver: the 75-NS-1 and the 75-NS-2. Both are based on the design and circuit of the 75-NS-3, but do not have the band switching and frequency range of the 75-NS-3 receiver. The 75-NS-1 covers between 3 and 6 MHz, including the 80 and 60 meter amateur band. The 75-NS-2 covers between 6 and 12 MHz, including the 40 and 30 meter amateur bands. Both units have the fixed ceramic resonator band width set for about 6 KHz. And, of course, they are both designed to fit in the tasty potted meat can!! All other specifications presented apply to both of these models as well.
Pricing of the 75-NS-x versions:
Type 75-NS-1 Mini HF Receiver Semi-kit (covers 3 to 6 MHz) $189.95
Type 75-NS-2 Mini HF Receiver Semi-kit (6 to 12 MHz) $189.95
Type 75-NS-3 Mini HF Receiver Semi-kit (band switched from 3.5 through 12 MHz in three switched positions) $269.95
Shipping and Handling to within the US $10.00 each
Readers: if you haven’t checked out the SWLing chat room, I would encourage you to do so! There’s almost always someone there and, many evenings, readers share reception reports in real time. Click here to check out the chat room.
After publishing my initial review of the Sangean ATS-405 on July 25, I contacted Sangean and requested a sample radio for comparison purposes. Back story: there were some receiver performance issues that I suspected may have been tied to my particular ATS-405 unit. Sangean kindly dispatched another ATS-405 which I received last week. The following is an update to my initial ATS-405 review.
In truth, there were two main reasons I wanted another unit to compare to my initial review radio:
I wanted to see if the new unit showed improved performance–sensitivity, selectivity, and, specifically, noise floor–in comparison with the first review unit tested
I noted strong DSP “birdies” (noises) on 800 and 1600 kHz on the test model, while several of our readers commented that their ‘405s did not feature birdies
Shortwave sensitivity/selectivity and noise
I noted in my initial review that the initial ATS-405 had an ever-present noise, a sort of low-volume static hiss. The noise floor, while not high, certainly seemed to be higher than other comparable shortwave portables, and was most noticeable when tuned to marginal/weak stations. I suspect many listeners may not notice it unless they compare it with other portables.
Fortunately, my new review unit’s noise floor seems to be slightly lower than that of my initial review unit. [Perhaps this unit’s board is better soldered–?] The noise is still there, but can be better mitigated by judiciously using narrow filters and the three-position audio tone control.
I suspect this is a noise somewhere in the audio amplification chain, because I find it less noticeable with headphones, and more pronounced via the ATS-405’s internal speaker.
In terms of sensitivity and selectivity on the shortwave bands, I believe my new unit is identical to that of the initial review unit. That is to say, the ATS-405 is not an especially sensitive shortwave receiver, but fairly average, and thus will fit the bill for most but not for the discriminating weak-signal hunter. Frankly, even my $46 Tecsun PL-310ET does a better job of pulling in weak stations.
I’ve tried tinkering with the AGC settings and soft mute–very cool features!–in an attempt to improve sensitivity, but alas, these only help the quality and stability of the received signal.
Birdies
Immediately after opening the box of the new ATS-405 sample, I popped in a fresh set of AA batteries and tuned the Sangean to 1600 kHz AM. [If you read my initial review, I noted a strong DSP birdie on 1600 and (to a lesser degree) on 800 kHz].
At first listen, I was happy to note that the new unit lacks the wild DSP noise that overwhelmed my favorite local station on 1600 kHz.
As I listened more carefully, though, I did note a metronomic “chick” sound that was also present but partially buried in the noise on my initial ATS-405.
Below, I’ve embedded audio comparing the two receivers:
Initial review unit:
New review unit:
Listening to these samples, I realize I may have had the filter set to the middle position on the first sample and the wide setting on the second (hence, the brighter tone).
To further demonstrate the difference between the two, I made this short video; I start with my initial review unit, then switch to the new review unit provided by Sangean:
Note that this was recorded at least 100 feet from my house on the tailgate of my pickup truck. DSP birdies on 800 kHz sounded very much like the 1600 kHz sample, save the noise level on the latter is slightly lower and there are no broadcast stations in the background.
None of my other portables have digital noises or birdies on 800 and 1600 kHz.
So, the bad news: I do still hear a noticeable (and slightly annoying) internally-generated noise on the new review unit. The good news: it isn’t as objectionable as that on my initial review unit.
While the new ‘405 review sample seems to perform better than the initial ‘405 sample, I find the discrepancy somewhat marginal, especially since I spend the bulk of my time on the shortwave and mediumwave bands.
I’m not a fan of production runs where units vary so greatly from one to another, making accurate testing difficult. Therefore it’s quite possible you might receive a unit that performs better than those I tested…but unfortunately, the opposite is also true.
So, if you’re a Sangean fan, if you don’t mind the birdies on mediumwave, and if you mostly listen to strong shortwave stations, you may entertain purchasing an ATS-405. The keypad layout is almost identical to previous Sangean models.
To be clear, of course, this radio’s negatives above have been viewed under a microscope; the ATS-405 is not a “bad” receiver, it’s just not that exceptional. Other than the added mute/AGC/squelch features, when compared to its predecessors, it’s really not a better iteration.
Many thanks to Jarkko Mäkivaara with Siru Innovations who writes with the following update:
We have added some new features to our SDR20 portable radio!
Please see the video [below] for a demonstration of the following features:
* Smooth zoom in FFT/waterfall view
* Adaptive menu
* Frequency memory with snapshot pictures of signals
* Sliding effect between views
* Keyboard beep
* FM broadcast receiver
* Example of Ham radio transceiver with Narrow-FM mode
You also might got the email sent out Today where this is in HTML format.
Many thanks to SWLing Post reader, Paul, who commented with a link to the new Degen DE221 “ultralight” radio: http://ebay.to/1fKWZ2m
Paul’s link lead to the discovery of several new Degen models, in fact. Many of the new models have the same form factor–and a slightly different model number–from their predecessors.
There may be even more 2015 Degen models than those I listed here and, in fact, they could’ve been on the market for a while.
I’ve already purchased the Degen DE221 for review since its predecessor, the DE321, was an acceptable radio for the $20 price tag. The DE321’s analog dial made for very vague tuning, however, so I’m curious if the DE221’s new digital display will be a worthy improvement. At this point, I don’t plan to review any of the other models above.