MW DXing with the Realistic DX-350 / Sangean SG-700L

As I have mentioned in several previous posts here, one of my hobbies is Long Distance AM/MW band radio listening (also known as AM/MW 'DXing').

The Realistic DX-350, a small analog tuned AM-FM-SW-LW radio made by Sangean. The top one was made in Taiwan. The bottom one (badged "Radio Shack" instead of "Realistic") was made in China.

I use several radios for MW DXing. None of them are high end models. They're all portable radios. This is for a couple of reasons. The first reason is economics. I just can't justify spending $500-$1000 for an Icom R-75 or Drake R8 to listen to long distance AM radio. The hobby is fun, but not so important to me that I would spend more when I can make do or spend less.

The second reason is I prefer the challenge of using radios I already have bought over the years, and making do. A lot of DXing is skill, anyway. I live in the NW US and I've heard Mexico City and Alaska on a boombox. I've heard Cuba on a Radio Shack Pocket Radio.

You don't necessarily need a high-end radio to get results.

Radio Shack now seems to be in financial dire straits, but they used to be THE store here in the U.S. to go to if you were a radio enthusiast and wanted a radio that not only worked, but worked rather well. Consequently, like many radio enthusiasts, I have a few Radio Shack branded radios.

RADIO SHACK AM/FM/SW ANALOG GEMS

I decided to post some info on a couple Radio Shack models I use for MW DXing that aren't mentioned by a lot of DXers online: the Radio Shack DX-350 & 350A. There isn't that much info online about them, either. And because there is so little information online about the DX-350's, this article is a little more in-depth than it normally would be.

Both DX-350 models were sold by Radio Shack in the 1990's and 2000's. I suppose by now they would be considered relics, but they work well, especially on the MW band.

The DX-350 was Radio Shack's version of the Sangean 700L radio ("L" standing for Long-Wave, as the 350 has a LW band as well as AM, FM, and SW.

The DX-350 has reasonably high fidelity -- especially through the headphone jack -- and is fun to listen to SW with, and is fun to DX the AM band with.


Of course, the DX-350 isn't available new anymore, but some online retailers carry them used, and I am certain they are available on auction sites like EBay.

Naturally, a DX-350 won't compete with a tabletop, high-end DX radio -- but with a loop next to one, it will do quite well. With a loop next to my DX-350A, I can hear what I hear with a Superadio.

And if you seriously want to hear something from very far away on the MW/AM band, you probably are using an external loop, anyway.

REALISTIC DX-350 AND DX-350A

The "DX-350" is actually two separate radios (DX-350 and DX-350A). It is an analog tuned 12 band radio -- AM, FM, Longwave, and SW in 9 bands (49, 41, 31, 25, 21, 19, 16, 13, and 11 meter shortwave bands). The MW band tunes the North American X-band, up to 1710 khz. The radio is reasonably small, and would probably fit into a large shirt or coat breast pocket (if you wanted to take one on a trail, or on a bicycle, for example). The DX-350 runs forever on a set of 4 AA batteries.

SANGEAN RADIOS

Both DX-350's are Radio Shack versions of the Sangean SG 700L and SG 700LA, respectively (the "L" apparently stands for "Longwave"). The later version of these two radios, the DX-350A, was marketed as a "DX-350", but the Radio Shack catalog number, and Sangean's ID# on the radio's printed circuit board both have an "A" attached, indicating the updated model.

Some time during these radios' run, Sangean moved production from Taiwan to China and completely re-designed the radio, with a different chip and PCB.

These are identical looking radios on the outside, and the specifications are similar. They look different on the inside, however. The difference is the IF chip used , as well as the number of ceramic filters used on the AM and SW bands. Other components are different also. The 350A has more 'mini' IF cans. In performance, the DX-350A is a bit more sensitive, and the DX-350 is more selective. On FM the sound is full but in mono, not stereo.

The Taiwanese made Realistic DX-350 with the front off. You can see the numerous tuning coils (those little metal square 'cans') used to tune the various SW, MW and LW broadcast bands. The Toshiba TA8122 IF chip can just be seen to the left of the tuner (the tuner is that big clear plastic thing in the middle of the radio). The radio receives FM in mono, so it just has one audio chip. The sound through the speaker is fairly good for a small radio.

The earlier of the two models, the DX-350 / SG 700L, was made in Taiwan, and it has a TA8122 IF chip and a separate, mono audio chip. It has two ceramic filters on AM and SW which narrows the bandwidth and makes it a good DX radio. It's an excellent MW DX radio, especially if you use an external loop. The selectivity is robust, and the sound through headphones is full and smooth. Being that it only has a 120mm X 8 mm loopstick, it's not a Superadio, but in high signal areas it probably can give most portables a run for the money.

A pic of the DX-350A's 120mm MW/LW loopstick, showing its flat top (the bottom is flattened also), making it compact but still 8 mm wide. The loopstick, plus the hot CXA1019 Sony chip inside the 350A is probably what makes it perform better than you'd normally think. The loopstick on the earlier, Taiwanese made 350 is identical.

The DX-350A / SG 700LA was the updated version of the radio. It was made in China, and instead of a Toshiba chip, it has a high-gain Sony CXA1019 IF chip which performs all functions. This same chip is used in some Sony headsets and clock radios, but it's also used in their ICF-38 AM/FM radio, which is also a very good performer.

HIGHER FIDELITY DXing

The 350A has a single ceramic filter -- similar to the set up in your average table radio or boombox. It sounds like it's about 8 khz or 7 khz wide, which gives a full sound on AM and SW -- through headphones the sound on the MW/AM band is amazing. Shortwave stations sound rich and full also through headphones. On SW you can hear heterodyne whistles when there are two stations really close to each other, but in today's sparse SW environment that's less of a problem than it used to be.


It is a terrific radio for IDing a MW station on a crowded channel. The sound is so lush through headphones that it makes DXing a pleasure. Over the past several years since I rediscovered the hobby of MW DXing it's probably the radio I enjoy using the most, because of the headphone sound.

There is a plus and minus to higher fidelity on a DX radio. The plus is that it sounds great. And you can ID stations easier when you can hear the audio better, especially the highs, which usually get cut on a narrower bandwidth radio. There is less midrange, and it's next to impossible to get listener's fatigue on a 350A.

However, the drawback from the 7-8 khz selectivity is that you get more splatter and interference from strong channels nearby, and on some occasions a strong local may swamp a weak adjacent. In this case, using an external loop and placing it 6-8 inches (130mm to 200mm) away from the radio helps.

As the CXA1019 chip -- which is the heart of this radio -- has a built in RF amp on AM and SW, the radio is fairly sensitive. It's obviously not a Superadio, but with a loop it can probably match one in sensitivity.

FM PERFORMANCE - DECENT ON THE 350, OVERLOAD ON THE 350A WITH WHIP EXTENDED

On FM the Taiwanese made DX-350 is fairly selective and pulls in most, if not all, FM stations that my other SW digital portables pull in. Not being an FM DXer, I have no idea how well this radio would work for such pursuits. But it has a decent FM section, with little overload.

The CXA1019 which the 350A uses also has an RF amp section for FM, so it will pull in stations, but the high gain and fairly wide bandwidth probably makes it a poor FM DX radio. Comparing the 350A to the 350 I have found that it has a tendency to overload on FM at my location. I have to keep the whip antenna retracted to get decent FM reception. With the whip retracted I receive most the local stations, including stations in the public section of the FM band and the sound is full and pleasant. But the overload and wider bandwidth precludes reception of fringe stations. The only way one could DX with the 350A is to be away from local transmitters, or find a terrain shadow. In this way it's probably like your average boombox of the 80's or 90's -- decent reception, but will only DX in certain locations.

For tuning the FM band, the Taiwanese made DX-350 is much better.

The inside of the Chinese made DX-350A. As can be seen (when compared to the similar pic of the Taiwanese made DX-350 above) the components are different; they are in different places, and there are less of them. The two versions of DX-350 are almost like different radios. Of the two DX-350 radios, I've used this Chinese-made one the most.

As the CXA1019 chip has an electronic volume control (in other words, the adjustment in volume is actually controlled by a function inside the chip itself), chances are very slim that the DX-350A's volume control will ever get scratchy, which is cool.

DECENT FOR SW BROADCAST LISTENING OR BANDSCANNING -- BUT CAN HAVE LOCAL FM INTERFERENCE

Both versions of the DX-350 are fun for bandscanning and listening to SW radio broadcasts. In 2012 I heard CKZN, St. John's, Newfoundland, one evening on my DX-350A, just off of its whip antenna. It was just underneath CKZU, Vancouver, BC (200 km away), on 6160 khz. There was a definite echo on the CBC programming, and then the second station, CKZN, went to a separate local newscast. It's the only time I've heard that station, which is a fairly low power station. Obviously, atmospheric conditions were excellent. But it's an example of the radio's ability to hear stations on SW.

I sometimes use my DX-350's for listening to SW broadcasts while working out in my workout/storage room. Living in the NW US, Asian stations come in quite well. Just before writing this, I heard the Voice Of America on my DX-350A, broadcasting in Korean on 9800 Khz., while working out.

If you're located near strong FM stations you'll get some FM hash on the SW bands on the DX-350's, which I 'null out' by moving the SW whip antenna until it's mostly gone. Strong SW stations will cover such hash completely. Of the two radios, the Taiwanese model with the narrower selectivity has the least amount of FM hash on the SW bands.

LONGWAVE

Both models receive longwave. I've never LW DXed with either radio, but I was hearing a few local NDB 'beacons' (up to 50 miles away) until my router and other local RFI covered the LW band with buzzing and hash last year.


My guess is with a good LW loop one could probably LW DX with a DX-350. Not having a longwave external loop, I haven't tried that.

LOW BATTERY DRAIN

As both DX-350's use 4 AA batteries and have very low current drain, they just go and go and go and go and go before the batteries die! They would make excellent emergency preparedness radios. Aside from DXing with the radio, I sometimes use my DX-350 around the house, to listen to football games in my workout room. I change the AA's maybe once or twice a year (I listen mostly on headphones, though -- except when listening in my workout room). There have been times I've taken AA's out of a digital SW portable and popped them into my DX-350's and the radios will still work for a while on them.

USING AN EXTERNAL LOOP

Two years ago I did most of my DXing on the MW with my DX-350's and a loop. To get a little more selectivity out of the 350A (the model made in China with the single ceramic filter) I just moved the external loop further away from the radio, which definitely helps.

My DX-350A inside a box crate loop which I made from 110 ft. of wire (around 33 meters) and a tuner from an old AM radio. Setting it inside the loop works well unless more selectivity is needed.

One thing I've discovered is that with both of these DX-350 versions, if you use an external loop, it's best if you keep the loop 5-8 inches (13-20 cm) or so away from the side of the radio. Even with the more selective Taiwanese made 350, you'll get a little more gain that way.

I have been able to DX with a box crate loop (as shown in the picture above) by setting a 350 or 350A inside the loop. But in cases where I needed more selectivity, I've set the radio outside the loop (as mentioned before), maybe 6 inches distant (15 cm).

This is especially needed with the Chinese made DX-350A, which is less selective. On channels with no local adjacents, setting the loop next to the radio will add gain, but on channels with strong adjacents, the target channel can get swamped unless you place the loop 5-6 inches away.

GREAT SOUND THROUGH HEADPHONES!!

Of the two versions of the DX-350, I use the 350A a bit more often because it's a little hotter, and the sound through headphones on the AM band is so lush. It's very useful for hanging out on a 'graveyard' MW channel (a channel which has numerous stations on it) to catch an ID, because the higher fidelity makes it easier to catch ID's. It's a little less useful for hanging out on a channel near a strong local, because unless you set the external loop just right, it can be a bit difficult to null out the splatter. Every radio seems to have a trade off of some sort -- the fidelity vs. selectivity is the trade-off here.

GOOD FOR EMERGENCY PREPAREDNESS, TOO

If you have one of these Radio Shack radios -- or their Sangean equivalents -- and are into MW distance listening, they're worth trying out. And if you are into emergency preparedness and you have one of these radios, bear in mind that they pull in stations well and are very, very light on battery usage. In the event there ever is a grid failure (God forbid), a DX-350 loaded with fresh AA's will last quite a while, especially if headphones are used (the radio is small enough to fit into a large coat pocket).

And face it: you can stock up on AA's cheaply and store them in a shoebox, if necessary -- or store them out of the way, in a small drawer. Several sets of AA's would probably drive a DX-350 for a year.

ADDENDUM, May 22nd, 2024:

After a few years of not using my DX-350's much, I started using my DX-350A on MW and SW. With MW, it took a bit to get used to using the radio with the loop, as it had been a while since I DX'ed with it a lot. On SW, however, I learned a new trick -- to use a wire antenna with your DX-350 or 350A, rig up a resistor or two to clip between the wire antenna and your DX-350A / 350. I had rigged up a couple different resistors to try out with other radios. The resistors themselves were a little high in range -- 47K ohms and 33K ohms, but with a high gain radio like a DX-350A the resistors seem to cut down the signal levels off a wire antenna and reduce and/or eliminate overload. 

Ideal resistor values would probably be between 250 ohms to 1K-2K ohms or so. 

Being that one 47K or 33K resistor seemed to cut down signals a bit much, I used both in parallel, giving me roughly 19K ohms, which was enough to cut down overload, and still pull in WWCR, WRMI, Marti, Reach Beyond Australia (in Korean to Korea), Radio Educacion, CFRB Toronto (6070). WRMI on 9955, and a bit of Missionaria on 9665 -- all clearly, except for Missionaria, which was really weak on all my radios last night. All stations were on the 49, 41 and 31 meter bands. I also got armchair copy off of Radio New Zealand on 9700, and KNLS's Russian service. The last two stations were strong enough the whip would probably have brought them in, but with the resistors, I was able to use my 25 ft / 9 meter indoor wire without worrying about overload. 

To connect the resistors? Use alligator clips. One end of the resistor hooks around the set screw on the alligator clip, and you tighten that down -- and the other resistor lead is for your antenna lead to clip to. To run two high value resistors in parallel if you don't have a 200 ohm or 500 ohm resistor, just clip the two resistors to the whip next to each other, and clip the antenna lead's alligator clip to both of the resistor leads.

Here's a 2024 pic of the DX-350A with the two resistors, in parallel, clipped between my 25 ft. wire and the whip antenna. This particular night I was able to DX the SW bands with minimal overload using this method. I took the pic while listening to a station in the 31 Meter SWBC band.:

It just goes to show you -- you never stop learning how to use your radios. :-)

C.C.