Sangean ATS-405 AM/FM/SW Radio

Sangean has upgraded its ATS-404 with the new ATS-405 portable radio and I was excited to find that  this new model offers several important new features radio lovers has been clamoring for ever since DSP (Digital Signal Processing) appeared. Externally the two models look quite similar but internally and operationally this is a completely revamped radio with improved performance and features. At its introduction it was generally available for just under $90.00 plus shipping and now it is in the $70’s at Amazon.

In a nutshell, DSP puts almost all of a radio’s receiving circuits onto a single pre-programmed chip. This eliminates lots of discrete circuitry and allows for economies of production and theoretically improved unit-to-unit consistency. DSP also has provided in many models, breakthrough FM performance, once achievable only in the most sophisticated equipment.

But, as with many new technologies, DSP has not been without its problems. First, AM performance has often suffered from digital noise – referred to as birdies, hets or whines –  created by these complex chips, so many DSP equipped radios have performed less well on AM than their predecessors. Additionally, some “features” built into the chips have not been to the liking of serious radio users…chief among them, something called Soft Muting. Soft Muting is supposed to reduce the noise between signals, or when signals fade, but it has many deleterious side effects, such as muting then surging (also referred to as “pumping”) of the audio as a signal falls below a certain threshold, then fades back in again. It can also reduce the volume if you try to tune away from the exact center frequency of an AM or SW signal, such as when you are trying to avoid interference from a neighboring signal…again, an annoyance. Finally, many digitally-tuned radios, even before DSP, are hampered by muting while tuning, which makes band scanning difficult compared with radios that let you hear everything as you tune.

Although the ATS-405 is not a top of the line radio (for example it does not include SSB or Synchronous Detection), it nevertheless is a bold step for Sangean in that there are now dedicated keys that let you turn off Soft Muting and Tuning Muting – this is exactly what we have been waiting for. It also offers fully adjustable and defeatable Squelch on all bands, three different AGC Gain settings in addition to the usual Local/Distant switch, three bandwidths and a three position Tone switch. There are two oddities; the ATS-405 includes FM RDS but only the “CT” (time set) function is available. I suspect this is because RDS has become more or less standard on most of the DSP chips but it would require a more expensive LCD display to make use of it. Also, there is no Auxiliary Antenna input jack, although I got good results clipping a short random wire to the rod antenna. More on this later.

Features & Details:

Frequency Coverage:

MW/AM: US 520-1710 / Europe 522-1710 10KHz/9KHz steps

FM: 87.50 – 108/76-108 With Stereo/Mono Switch for headphone listening

SW: 2.3 – 26.10 MHz Continuous Coverage with 14 Meter Bands

Soft Mute – Defeatable

Tuning Muting: Defeatable

Squelch: Defeatable and Adjustable from 1-10

108 Presets / 36 each band for AM/FM/SW

Wide/Normal/Narrow bandwidth selection for AM/SW, Wide/Narrow For FM

Five Tuning Methods: 10 Key Pad Direct Frequency Access, Auto Scan, Manual Tuning, Memory Recall and Rotary Tuning

Fine Tuning with 1KHz steps

Three AGC Gain Settings working in the IF stage

Local/Distant Switch working in the RF stage

Built-in battery charging with LED indicator/uses 4AA Batteries

Carry pouch

Three Position Music/Normal/News Tone Switch

Clock (12/24 Hour modes selectable) /2 Alarms/Sleep Timer/Snooze function

Headphone and DC In jack

Lock Switch

Size: 6.4″ Wide x 3.9″ High

Initial Impressions: Sangean always packages their radios beautifully. Opening the box revealed a few surprises. First, there is no external antenna, either reel-up or plain wire, such as those usually supplied with shortwave portables. After looking at the radio I realized the ATS-405 does not have an external antenna jack…a relatively rare omission. You can always use a clip-on antenna or simply wrap some wire around the rod to get enhanced SW sensitivity, or a small loop which needs no connection to enhance AM reception.

The ATS-405 comes with the usual protective carrying pouch. Also in the box an AC adapter for charging rechargeable batteries or for operating the radio on AC power…it seemed to work well and introduced little noise in my tests. No earbuds are supplied.

Adjustable Squelch – Tuning Mute Soft Mute Status: This is something I’ve been waiting to see and hear but I didn’t expect to see it for the first time on a sub $100 radio. Apparently Sangean has listened to its customers and allows them to defeat all of these three mute functions…the ATS-405 is the first portable radio to accomplish this and to make it completely user-friendly without hidden menus and not dependant on firmware revisions…thank goodness. All of these options as well as others are available with the radio either on or off which is very user friendly, via the use of a Menu Button which enables a secondary set of features associated with the numeric keys. Most of the numeric buttons are labeled with these secondary functions: Squelch, T-Mute, S-Mute, 9/10 K tuning steps, AGC Gain and others allowing you to easily turn any or all of them off or on at your pleasure. Finally!

Squelch works on all bands and can be turned Off or adjusted between 1-10 for each band (AM/SW/FM individually. Signals below the threshold you set are silenced and this also affects auto scan functions so, for example, if you are in an unfamiliar city you could set it fairly high and find only the local signals. A nice feature.

Tuning Muting silences the radio while tuning which radio hobbyists have disliked ever since the advent of digital radios. Some radios have it…some don’t. Now you can have it your way and turn it on or off as you wish…unbelievable! I leave it off.

Soft Muting can also be defeated as was already described.

Use Tests – AM Performance: The first thing I did was to check AM reception and I was pleasantly surprised by the Sangean’s good performance on this band. The AM reception was quite a bit better than the Tecsun PL-660, PL-680 and PL-880 which were hissy on AM by comparison. The Sangean was about on a par with the Eton Satellit on AM reception. This is great performance at this price level. The AM was also refreshingly free of digital hets or birdies which are common with many DSP portables and with the ability to defeat soft-muting and tuning muting it is a delight to band scan with. This is a great little AM portable. There are three bandwidths for AM and SW…although the manual states these are nominally 6K, 3K and 1.8K on AM (4K, 2K and 1K for SW) they are audibly much more trebly than this might suggest. On AM the widest setting is very bright sounding…like FM. On good signals many people will like this…I did most of my AM listening in the middle bandwidth setting which to my ears produced a very natural sound with excellent selectivity. I kept the News/Normal/Music tone switch in the Music position.

SW Performance: SW performance is decent compared with the other portables it competes with. I tuned many weak and medium strength (daytime) SW signals on all the radios in this group and they were generally so close that moving the radios produced bigger differences than those inherent in the radios. Even a short random wire produced far bigger gains…since the ATS-405 has no Aux Antenna jack I clipped it to the whip where it worked well. The ability to defeat Soft Muting was a definite plus. At night the ‘405 was a bit less impressive on SW compared with the other radios in this group. Sometimes it showed better audio clarity which helped but overall signal levels seemed weaker than the Tecsuns and Eton. Also remember…the ‘405 has no SSB so if that is important to you you’re going to have to look elsewhere. I hope Sangean updates their 505 with the new levels of performance and features they have lavished on the ATS-405…that would be a another great addition to their line.

FM Performance: Another example of what DSP can do…the ATS-405 is a good FM receiver with excellent selectivity although it was not quite as sensitive as the other radios in the group. Most of my usual stations came in just fine but I was able to dig out a few traces of very weak signals on the other radios that were just not there on the Sangean. This won’t affect most users but this is not the radio for FM DX’ers. Sound was good on FM and stereo sounded great through earbuds.

Sound: While certainly no boombox, overall the ‘405 sounds quite nice. On FM the sound is clear and natural..on AM and SW as I mentioned the wide filter seemed a bit bright but you have the three position tone switch and also a medium and narrow filter which also tame those highs. I did most of my AM/SW testing in the middle bandwidth position.

Sangean specs the audio amplifier at 1 watt output running on batteries or 1.5watts when operating on external DC. That’s quite a bit of power for a smallish portable where most radios typically run around 1/3 to 1/2 watt at best. The radio does play loudly when desired with little apparent strain and audio is very good for its size.

AGC Settings versus the Local/Distant Switch: One unusual feature on the ATS-405 is a three position setting for the IF AGC Gain affecting AM/SW but its description in the owner’s manual left me scratching my head such that I had to experiment with it to figure out what it was doing. Automatic Gain Control attempts to keep all signals of varying strengths playing at the same relative volume, so weak signals are just as loud as strong local signals. All modern radios have AGC. This AGC setting does not turn the automatic gain control on or off as its setting names would imply nor does it affect the AGC time constant…it is a change to the overall gain of the IF AGC circuit in 10 db steps. It’s settings are 30db, Auto and 50db but it should be more intuitively labeled Low, Medium & High since the AGC still regulates signal levels automatically in all three settings. The setting has little to no effect on the quality or signal to noise ratio of the received signal. Rather it changes the range of signals that the AGC can handle without losing volume on weaker signals or overloading (distorting) on stronger signals. Although the default setting is “Auto” I recommend using the 50db setting unless you are in a very strong signal area and experience overload or at night if fading produces audible pumping – then, a lower setting might help.

The Local/Distant Switch (Local/DX) works at the RF input stage where it does have a profound effect on received signals. Leave it in DX unless you experience strong signal overload. BTW…the manual says it works on all bands but it does not work on FM.

Conclusion: The Sangean ATS-405 was a surprise in many ways. I expected an average-performing radio with typical features but what I found was a breakthrough in terms of being able to control aspects of the DSP chip we’ve all been clamoring for. AM Reception is as good as the Eton Satellit and better than any of the Tecsun portables. SW is excellent in the daytime…about on a par with the competition, but nighttime SW was a bit weaker.  FM is selective but hair less sensitive. If Sangean chooses to upgrade the next model up in the line, adding an Aux antenna jack and SSB while retaining the features and good AM of the ATS-405 that would be another great addition to their line. but as it is the ATS-405 offers solid overall performance and some breakthrough features that radio lovers are sure to appreciate.

See It At Amazon:

Jay Allen