MW DXing with the REALISTIC DX-398

My Realistic DX-398, Radio Shack's version of the Sangean ATS-909. If you look closely, you can see where I ground down the 'LOCK' button, to keep the radio from turning itself on when I had it inside my backpack.

The Realistic DX-398 is a radio that's been around for a while. In fact, they were introduced in the late 1990's -- the DX-398 is Radio Shack's 'version' of the Sangean ATS-909 digitally tuned SW-AM-FM-LW radio.

I've had mine since the very late 90's. For a while it was my main SW radio, and I used it all the time to listen to ham radio stations because the sideband and CW reception is so good on this radio. To DX the SW and ham bands with the 398, I used a 25-30 foot (9-10 meter) indoor wire, plugged into the antenna jack with a mono plug.

Although the DX-398 has a good MW section, I never used the radio for MW that much because of its somewhat muddy sound on AM, and I had other radios I preferred for AM band listening and DXing. Every now and then I'd listen to FM stereo on it though the headphones. But for the most part I'd use it on SW.

KPQ, Wenatchee, Washington, an AM station that can be heard in Seattle on 560 khz.

 

The fact that I used the DX-398 so much is apparent from the looks of the radio. The plastic stand in back of it is gone -- like most DX-398 owners discovered to their chagrin, it breaks easily. I have mine stored in a drawer somewhere.

I've probably taken the back off of my DX-398 more than any other of my DX radios. I first took it off to seal the edges of the plexiglass display window to the case, to keep dust from getting all over the LCD readout. Then, a few years later, the radio became intermittent. It was the negative battery terminal, which needed an extra shot of solder to hold the spring to the radio's printed circuit board. Hitting the terminal pad with solder solved the problem, and it's worked great since then.

Here you can see where I used a Dremel tool to grind down the "LOCK" button. After that, the radio no longer turned itself on when it was bumped. Recessing the "LOCK" button in this way really did the trick.

I ground down the "LOCK" button on the front of the radio because when I took the radio to work with me it would still turn itself on when jostled or bumped inside my backpack. Grinding it down solved that problem.

More recently, I ground down the little plastic 'guards' around the Tuner button with a knife file, because they just got in the way. The tuner button now has a more positive feel. I also took the back off the radio last year to spray-clean the insides of the tuner mechanism because it was starting to skip. Since then, it's worked like a gem.

The DX-398 with the front of the radio off. The button mechanisms are all plastic, as used in most computerised equipment. But they work well, and have a positive feel. The large LCD readout can attract dust -- which is why I glued the plexiglass readout window to the front of the case.

 A LOT HEARD ON MY 398 OVER THE YEARS

I used to take my DX-398 to work with me, and it was the radio on which I heard the first news reports of the terrorist attacks on the World Trade Center on September 11th, 2001. I've used it to tune in CB outbanders from Latin America and the Caribbean; 10 meter beacons; chanting 'pirate' hams from Kalimantan in Indonesia on 6999 khz and in the lower reaches of the 40 meter ham band; some tropo FM catches (mainly BC Canada FM stations); hams from all over the world during DX contests; and numerous stations from Asia and the Pacific rim on the 41 and 49 meter SW broadcast bands.

The only thing I didn't use my DX-398 for, ironically, was DXing the Medium Wave / AM band.

SOME HISTORY OF THE DX-398

The DX-398 / Sangean ATS-909 was the watershed in SW radios. Although it was a little expensive at the time, it was packed with features and was a very good performer for the money. Along with its replacement the Sangean ATS-909X, it is one of the few SW portables that will work with an external antenna without a lot of overload.

The DX-398 also came from the factory with a couple hundred shortwave stations (261 in fact!) programmed into the radio's memories. The DX-398's memory "pages" -- and ability to edit the page labels -- was a new idea for a SW radio, and was very useful once you got used to how it worked.

I soon re-programmed the memories on my DX-398 by SW target area and type. For example I had one "page" for aircraft frequencies only, another one for hams (I'd program in the first frequency of each HF ham band I monitored), another one for ships, etc. etc.

The DX-398 tuned to a station in Eastern Oregon -- KUMA 1290 in Pendleton. Here you can see how on MW you can label each of the eighteen MW memory locations (two 'pages' of nine memories each) with alpha/numeric names.

Looking back, the fact that a company like Sangean put out a radio with so many pre-programmed memories shows just how far HF has dropped in importance. There are radios today with more memories than the DX-398, but there are vastly lower numbers of SW stations to listen to. You couldn't fill 100 memories with SW stations today, much less 261 -- with very few international broadcasters left on the bands, and few regional and national broadcasters receivable worldwide, there's no way a company like Sangean could pre-program so many memories with stations today.

On any given night or morning I now hear maybe 20 SW stations -- that wouldn't even fill a tenth of the DX-398's 261 SW memory locations. Most of the SW memory locations in my DX-398 are left over from 2003, when I last seriously DXed the Shortwaves.

RE-DISCOVERING MY DX-398

For maybe 5 or 6 years my DX-398 just took up space on my shelf, mostly unused. Recently I pulled it off the shelf and fired it up. For a lark, I decided to see how well it works on the AM band. I grabbed a wall-wart and took my DX-398 out to the storage room during an afternoon, just to tune around while working out.

The first thing I noticed was that KIT 1380 Yakima (200 km away, over a mountain range) was coming in at 4 in the afternoon. That was a good sign. Then I noticed my wall-wart was the wrong voltage! For some reason I thought the DX-398 took 9 volts when it takes 6. Wooops! Nine volts into a 6 volt radio -- not good! I immediately unplugged the wall wart. When I plugged in the 6 volt adapter, all was well. Whew! Luckily the higher voltage wall-wart didn't blow up my radio!

Lesson learned: Always double check the voltage on your radio and your wall-wart!

Over the next few nights I tuned the MW band with my 398. I always knew it was a pretty good radio on Medium Wave. But after a few DX sessions I've learned it's a better DX radio on  AM than I'd originally thought. First, the sound isn't as muddy as I'd thought. It's not a high fidelity MW radio, but you can still DX with it on a pair of headphones and enjoy the experience. Second, the radio DX'es well even without an external loop.

The DX-398 with the back cover off. At the bottom you can see the negative battery terminal spring. The solder pad -- to which it is secured -- has extra solder -- a fix I made when the radio went intermittent 4-5 years ago. It's the only 'glitch' my DX-398 has had.

SENSITIVITY AND SELECTIVITY = VERY, VERY GOOD

The DX-398 has very good selectivity. Mine will bring in CBR Calgary on 1010 right next to local KOMO 1000 and as long as conditions are decent, it's very readable with minimal splash. This is with the "Narrow" filter permanently engaged.

The selectivity in fact (at least in the 'narrow' position) is tighter than my PR-D5, which is a fairly well known MW DX radio. My DX-398 will pull in TIS stations and traces of a broadcast station in Ontario, Canada on 1610 that my PR-D5 reads with difficulty due to a local splash-master station on 1620. With the DX-398, I tune to 1609 and the Ontario station is more legible (the PR-D5 only tunes in 9 or 10 khz increments on the MW band).

On some channels the DX-398 will tune in between channels with no audio except some splash. The radio would probably be excellent for DXing Trans-Atlantic and Trans-Pacific stations for this reason.

The tight selectivity in the narrow position doesn't make for high fidelity listening, but there is no listener's fatigue, either, strangely enough. The sound is smooth and reasonably pleasant.

My DX-398 is permanently set to "Narrow/Mono" because I broke the "Wide/Narrow" button when re-closing the case the last time I had it open. So I set it permanently to Narrow, because that's where I always set it when DXing the ham bands with it. As I said, I've found it's a tiny bit narrower in selectivity than a Sangean PR-D5, and narrower than my DX-370 (which I've reviewed in another article here on my blog). I'm guessing it's somewhere around 3-4 khz wide -- reception can be altered after that with the tone switch on the side of the radio.

The tone switch has three positions -- you can hear the differences best through headphones. There's "normal", "news" (the narrow audio filter setting), and "music" (the wider, more scooped audio filter setting). Switching the audio filters while trying to ID a difficult station can help.

A side view of the DX-398 showing the tuner mechanism with the knob off of it. You can shoot tuner lubricant / cleaner down the side of the tuner shaft and it will clear up any glitching that occurs when tuning the radio using the knob. The shaft has just enough clearance to allow lube and cleaner to get inside the mechanism. It may take a few shots of lube and cleaner to treat it in this manner -- but it works.

SHORTWAVE SENSITIVITY GOOD -- NEEDS EXTERNAL WIRE

The DX-398 has excellent sensitivity. On Shortwave it is excellent with an external antenna.

On its whip antenna it is weaker than other, cheaper portables on SW, however. The design was a compromise to get more reception on FM off the whip, and an external antenna jack was installed for SW listening.

There are some who complain about the DX-398 / ATS-909 and 909X's "deafness" on SW, but this is not true. You just have to attach 15-25 feet (5-10 meters) of wire and either clip it to the whip or use it as an external antenna. It's very easy to do. Most serious SW listeners are using a wire antenna of some sort anyway, even if it's just the wind up wire antennas that come with many radios.  So I don't share the complaints others have about the DX-398's SW performance off the whip.

The radio has built in diode protection to keep the RF transistors from getting zapped in case of static discharges. Even so, I wouldn't use a long outdoor antenna in lightning country without caution.

A view of the DX-398 with the back off. You can see the MW/AM ferrite loopstick antenna -- it's not really large, but because of all the extra IF circuitry inside the radio it is quite adequate for DXing the MW/AM band. The extra circuits make the DX-398 a good performer on Longwave, also.

MEDIUM WAVE SENSITIVITY IS EXCELLENT

The DX-398's sensitivity on AM is a little surprising in that it only has a thinnish 120 mm loopstick. But the RF FET amp, and the several stages of IF amplification after that, all make up for the medium sized loopstick. My DX-398 also works very well with an external loop antenna. I only add it when needed.

My DX-398 will hear nearly everything my Sangean PR-D5 hears -- the other night I compared them both without any external antenna. The PR-D5 brought the distant stations (KBRE 1660 and XERF 1570) in with a little more readability, but the difference was minimal -- maybe 1.5 db or so.

Another view of the MW loopstick antenna, with a ruler showing it's 120mm long -- it's the average MW loopstick antenna used in many Sangean digital SW portable radios.

My 398 has slight overload on 1330 (a couple of my other radios have it on 1340 -- it must be due to a couple overly strong locals), mostly during the daytime, and another spot of overload on the higher side of 1380 -- both of which reduce in strength at night. There are minor images on 540 and a couple other frequencies, many of which come and go. None of them are so severe that they get in the way of DXing. Adding a loop eliminates them. Other than that, there are no glitches with reception.

MEMORIES ARE VERY USEFUL FOR DXing THE AM BAND

The radio has 18 memory locations allocated to the MW/AM band. This is very useful, as you can "edit" the memory location labels, and type in the call letters of stations you hear on those frequencies. I have the main regional DX stations labelled and saved on mine: KSL, KFBK, KUMA, KIT, KONA, CBU, CBR, KGO, etc.

On a couple frequencies I have more than one station labelled in a memory location.

LONGWAVE

The DX-398 tunes the Longwave band from 150-519 khz. Unlike a lot of Longwave radios available, it tunes the entire Longwave spectrum, including the Beacon band as well as the European LW broadcast band. The European LW band covers 150-270 khz., but above 270 are a lot of Non-directional aeronautical beacons, especially in the U.S. In the U.S., unless you have a really good antenna, beacons are the only thing you'll hear on Longwave.

I haven't tried any serious DXing with the DX-398 on Longwave using a loop, but I tuned around the Longwaves over the past few mornings and received most of the Puget Sound area navigation beacons with readable signals (fair to poor, depending on the evening).

The edge of my DX-398, showing the ground-down LOCK button and the guards around the tuning button, which I filed mostly flat to make it easier to turn the tuner knob without skipping frequencies -- you get a more positive grip on the tuner knob that way. I used a regular file.

More surprising is reception of several beacons from BC Canada, including the "ZP" beacon in Sandspit, BC, in the Queen Charlotte Islands, which is over 500 miles / 900 km away up the Pacific Coast.  I also received the "NY" beacon in Enderby, BC, about 300 miles away; the "SX" beacon in Cranbrook, BC, over 350 miles away; and the "YYZ" beacon in Quesnel, up in the BC Interior, over 300 miles away. These loggings were all made using the radio's internal antenna.

I also noticed that there are several RTTY (or similar mode) transmissions on Longwave. I've since discovered that they are "DGPS" stations, which transmit data used by some GPS receivers to help correct and improve the location data. There is a DGPS Longwave station just 8 miles west of me, on Point Robinson, Maury Island, which comes in at S5. There are also other DGPS data stations I've heard from as far away as Cape Mendocino in California; Lincoln, California; and Alert Bay, British Columbia.

I'm certain that with a good external longwave loop, the DX-398 would definitely DX the Longwave band.

A side view of the DX-398 with the front and back off of the radio. You can just see the tiny switch mechanisms used for 9 khz / 10 khz, tone, and wide/narrow buttons. The wide/narrow switch is the one exposed, just above the volume control (the knurled knob at the bottom end of the radio. I inadvertently broke the little plastic part of the switch, so I stuck it in the "narrow" / "FM Mono" position.

Unlike some SW radios, the Longwave band on the DX-398 isn't plastered with AM band interference, so the filtering on that band seems reasonable. I do get some RFI, in the form of very subtle carriers on several places in the LW spectrum (probably from my router), but it doesn't destroy reception on the band by any stretch.

Listening to the Longwave band is sort of relaxing -- the background noise heard when receiving a Longwave beacon is very serene sounding compared to MW and SW, for some reason. After logging the station in Sandspit, I'm planning on expanding one of my unused Plastic Crate MW loops for the Longwave band.

The DX-398, showing the World Clock button (circled in orange). Pressing it toggles the clock to whichever alternate time zone you choose for it. You can also use the tuner buttons to view the present time in any time zone in the world (based on world capital cities). I have my alternate time zone set to UTC/GMT, so all I have to do is press the button to see what time it is in UTC for logging stations.

WORLD CLOCK -- USEFUL FOR HAM OR SW BAND MONITORING

The DX-398 has several timers, none of which I've ever used, and a World Clock, which I use all the time. You set the time for your own time zone, and it automatically can tell you the time in every time zone of the world -- listed by world cities. I.e., you set your local time in Seattle, and using the World Clock button, you can toggle your way through the world's major cities and see what the time is in London, Stockholm, Dacca, Perth, Sydney, Hong Kong, Tokyo, or other places.

The World Clock is also useful for DXing the SW bands: it gives you an idea of whether it's night, day, or twilight in a given time zone. This can help you figure out usable DX paths to and from other areas of the world without needing a grey line map. Some SW bands work better at night, others work better during the day. Choosing a night time or day time path can help you decide which SW band you want to listen to, to hear stations from a certain area of the world. The World Clock feature also helps if you're listening to the ham bands.

IT USES A FAIR AMOUNT OF BATTERIES

The biggest drawback to using a DX-398 is the battery usage. A set of 4 heavy duty AA's only lasts maybe a week if you use it nightly -- even with headphones.

I've found mine DXes well with a 6 volt AC adapter -- no noise from the adapter gets into the radio. Of course, my adapters aren't the switching type -- switching power supplies will wipe out reception on any radio in the house.

I also made a battery pack for my DX-398 when I was using it a lot for ham band monitoring and DXing. Four D cells will drive a DX-398 for a long, long time. You just leave in the AA's to run the clock.

A closer view of the tuner knob 'guards', which I filed mostly flat, and the space around the tuner shaft where one can spray tuner cleaner or Deoxit to clean the internal contacts of the tuner, so it won't skip. Some DX-398 tuners will skip from oxidation and age, and tuner cleaner definitely helps. There is just enough clearance around the shaft to allow tuner cleaner inside. Then you turn the knob a few times to work it onto the contacts. One may need several applications alongside the tuner shaft to get the job done. This also works on Realistic DX-394's, which can tune in only one direction if a contact gets oxidized. DX-394's have a very similar rotary, mechanical tuner mechanism.

If one were considering a DX-398 for a preparedness / emergency disaster radio, several extra sets of AA's or a battery pack would be necessary, especially if power is out for more than a few days. And one would want to use mainly headphones, which lowers battery consumption considerably.

However, because of its excellent performance, a DX-398 would be a good emergency radio otherwise.

FM

The DX-398 / Sangean ATS-909 was one of the first SW radios available everywhere that had FM with RDS -- a Radio Data System that uses the FM signal to carry station ID's, song titles, etc.

At first I had no use for RDS, but recently have come to appreciate it a lot more, because it's the only way you can tell what song is being played.

FM reception on the DX-398 is very good. I'm not an FM DXer, I mainly listen to the local rock and pop stations. But I've heard stations from Victoria, B.C., Canada during 'tropo' conditions, and that's pretty good for the hilly area where I live. 

FM sound in stereo is very good through headphones -- although my DX-398 is stuck in mono because of the switch I broke last year.

The memory "pages" can be labelled on the DX-398 rather easily, by using the "edit" button (just visible in the lower right of the picture) and using the tuner knob to scroll through letters and numbers. The newer Sangean ATS-909X has similar functions. Here you can see where in 2002-2003 I labelled this bank of frequencies as "India", as all of the frequencies were of All India Radio SW stations I'd heard, or other SW stations aimed at the subcontinent. The 10330 kHz station here was an AIR SW station from Madras (Chennai) beamed at overseas Indian listeners in East and Southern Africa. Sadly, that station isn't heard here anymore. 

***THE SANGEAN ATS-909X***

The DX-398 was discontinued some time in the mid to late 2000's, and it was replaced by the Sangean 909X, an updated version with some extra memories, a few cosmetic differences, and a different case. For the most part, the AM-SW-LW circuitry is exactly the same in both radios -- They're the same design.

Although there is some speculation that the 909X uses a modern 'DSP' chip (the SiLabs 4735) for all receiver RF & IF functions (a burgeoning trend in modern radio design), a look at the 909X's schematic diagram shows differently. The 909X is a DX-398 / ATS909 with some different parts, a different IF chip, and a SiLabs 4735 DSP chip replacing its predessor's FM RF-IF chip (the chip that amplifies and filters FM coming off the whip antenna) -- otherwise, the basic design seems to be the same.

The Sangean 909X's FET's are different part numbers, and the IF chip is different (instead of a TA7758, the 909X uses Unisonic's version of the TA7640). The IF chip is also only partly used, apparently as an extra IF amp for the AM-SW-LW section. The way the chip seems to be configured, there may be one extra stage of amplification, which may explain the apparent improvement in reception some 909X users report.

There is an added standard transistor right in front of the switchable filters in the AM-SW-LW circuits on the 909X. Whether it adds to the gain of the 909X or not, I really don't know.

In the FM circuits there is no 'front end' RF-IF chip -- a SiLabs chip is used instead, which does the same thing and may provide some extra filtering. From what I've read, the 909X is a slightly better performer on SW than the DX-398 / ATS-909, and presumably it's the same with the MW performance as well, possibly because of the newer model transistors or IF chip used -- or maybe that extra bipolar transistor in front of the switchable filters.

Either way, if the ATS909X is as good as the DX-398 is for Medium Wave, it would be an excellent DX machine. Reports I've read on the internet of the Sangean ATS-909X's Medium Wave performance is that it is an excellent MW DX radio.

Here you can see the DX-398's little brother, the Sangean ATS-505 (also known as the Radio Shack "PLL Synthesised World Receiver"), with its back off. The MW/AM antenna is the long grey bar at the very top of the radio. It's 120mm long, just like the one on the DX-398. However, the 505 isn't as sensitive on MW as the 398, because it doesn't have the 4-5 extra stages of amplification and filtering that the 398 does on MW. The ATS-505 is still a good MW radio -- it's just that in low signal areas it's best to use an external loop. The radio sounds very good through headphones and the selectivity is amazingly good for DXing.

IN CLOSING

Although the DX-398 and its Sangean equivalent, the ATS-909, have been long discontinued, they are still available online, mostly used -- some I've seen for sale around $100 US. It's been my experience that there is very little that can go wrong with these radios, provided they haven't been misused, or provided that somebody didn't try to do an electronic modification and mess it up. The only defect mine had was a negative battery solder joint that took 10 years to go intermittent and it was a 15 minute fix (including removing the back of the radio).

The "tailgate" to my DX-398 (a plastic piece intended to prop the radio up at an angle), which broke once, and I tried reinforcing the corners with Delrin guitar pick material -- but to no avail. The tailgate ended up in the drawer, along with the flimsy handle that came off of my DX-390. Most DX-398 owners probably have the tailgates of their radios stashed in a drawer somewhere.

And, of course, if one wanted a new radio, the Sangean ATS-909X probably is just as good, if not a little bit better in performance.

The only problem I've read online that has happened with a DX-398 is the tuner button skips. I've seen this mentioned at least once online, so I'm certain some others have experienced this. This can be remedied by shooting tuner cleaner down the side of the tuner button shaft (a trick I learned when my DX-394 decided to only tune in one direction!).

As I discovered too late -- you don't have to take the back off the radio do do this -- you just pull the tuner button off the shaft, and aim a few good shots of tuner cleaner alongside the shaft (I used a paper towel to keep the overspray from hitting my eyes, or getting all over the side of the case). The tuner shaft has just enough play to allow tuner cleaner to get inside the mechanism and clear off any oxidation on the contacts.

You may have to do this several times for the cleaner to work its way past the shaft to the parts inside the tuner mechanism.

Above you can see a pic of my Cat Pumpkin, which I carved for Halloween 2014. It's probably my favorite pumpkin stencil that I've used for carving pumpkins -- I also used it this year in 2016. Although it's no longer Halloween, I decided to put the pic on this blog post, anyway. :-)

Here's hoping all of you who are into radio and DXing have a safe and productive DX season. And may the rest of you have had a good November & December, wherever you are.

C.C. 11-11-2016 and 1-21-2017.

ADDENDUM, December 3rd, 2022.:

My DX-398 has decided recently to act up on me. On battery, it turns itself off about 30 seconds or so after powerup, saying the battery is dead, even though I have fresh batteries in it. This has happened with more than one set of fresh batteries. So I know it's not the batteries.

The last time this happened, some time around 2011 or so, the negative battery spring had somehow weakened the negative battery solder pad on the radio's main PCB. Now it's acting up the same way again, and resoldering the negative battery connector isn't helping. So it's a repair that will have to wait until I have more time and patience. I'm guessing it's the positive side of the battery somewhere that is acting up this time. 

Radio works fine off the AC adaptor, so it's not the actual circuits. It's a physical connection somewhere.

Live and learn. -- C.C.

ADDENDUM, March 21st, 2023:

I found out what the problem was (the problem I had with my radio turning itself off on battery power). There was some corrosion on part of the positive terminal -- that little metal plate inside the battery compartment that delivers the positive side of the battery to the radio. The corrosion looked like white powder, with a tiny bit of green thrown in (probably because of the copper metal in the positive terminal plate).

I scraped the corrosion clean with a small screwdriver blade and then further cleaned it with a Q-tip cotton swab soaked in tuner cleaner. It took a bit of work to clean it up.

Now my DX-398 works like normal! I DXed with it both on MW and SW earlier this evening for nearly 45 minutes with no cutting off of the radio. I'm a happy camper. :-)

Lesson learned: check the condition of your batteries, and the condition of the terminals and hardware in your radio's battery compartment!

-- C.C.