- Category: Our Stuff
- Published: Thursday, 22 November 2007 14:19
- Written by Gary De Bock
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The Sony ICF-EX5 Portable Receiver on Medium Wave (by Gary De Bock)
As most medium-wave DXers know, after Sony discontinued the highly sensitive ICF-S5W in 1981, it has never returned to the North American market with a medium-wave DX specialty portable. But a little known fact is that the Japanese market has had a phenomenally successful medium-wave DX receiver sold continuously since 1985… the Sony ICF-EX5. Since this radio was strictly designed for the Japanese market, to my knowledge, it has never been offered for sale here. In addition, since almost all of the documentation on the web is in Japanese, the existence and competitive suitability of this portable unit are generally unknown in North America. Intrigued with the Japanese reports of outstanding sensitivity and selectivity, I placed a couple of orders for the radios, eager to test them out against contemporary portables.
In my opinion, the ICF-EX5 project was Sony’s attempt to improve the ICF-S5 design , by incorporation of double conversion circuitry, synchronous detection, and a more automated design. The ICF-S5 (and S5W, the North American model) was highly sensitive and selective, but suffered from mediocre image frequency rejection. Despite this notable shortcoming, the ICF-S5 radio was very popular in Japan, and the rarer S5W models are still highly sought after in North America, with decent units bringing $250 or more on online auctions (or five times their original price).
Like the S5 design, the EX5 radio covers medium wave (530-1640 kHz), the Japanese FM band, and has crystal-controlled coverage of the 6 Japanese NSB shortwave stations (NSB 1 and NSB 2, on 3, 6, and 9 MHz, but the crystals do not allow any deviation from the NSB shortwave frequencies). Unlike the S5, the EX5 also includes the North American FM Band (total coverage of 76-108 MHz). The EX5 has an analog design like the S5, but extensive efforts were made to automate and compact the circuitry, with the result that the EX5 is lighter than the S5, despite having one more “C’ battery.
The S5 and S5W are easily aligned for peak sensitivity and can be quickly adjusted to cover 530-1700 kHz, but the internal adjustments for the EX5 are sparse, and full coverage of the X band seems unlikely without component changes (assuming one has a Japanese-language service manual!). AGC performance on this portable is commendable, as it can tune quickly from a strong local (KIRO-710) to a fringe station (CHMJ-730) without any delay in AGC response. The EX5 has an AM sensitivity switch, and plug-in sockets for an earphone, and 6 VDC adapter (not included).
The rear panel has connections for an external antenna and ground. However, since the internal ferrite bar antenna is not disconnected by this terminal, the bar antenna can compromise the performance of a strongly directional external antenna.
While connection of such an antenna generally improves reception greatly (especially on the higher frequencies), it also increases image frequency susceptibility on the lower frequencies, and increases the risk of spurious signal generation adjacent to strong locals.
Also like the S5 design, the EX5 maintains an analog tuning dial, with the rather unique “linear scale” tuning system. In function, this means that frequency spacing is identical throughout the band, and that the tuning dial does not compress the higher frequencies into narrower segments. Although still an analog design requiring the user to “track” frequencies, this feature somewhat aids frequency determination, especially at the top of the band. As aligned by Sony, both review units had accurate dial calibration.
Physically, the EX5 very much resembles an ICF-2010, reduced in size about 20%. Whereas the 2010 has a keypad in the center right area, the EX5 has a list of Japanese stations arranged by frequency and locale.
Obviously, this feature would be of little use in North America, except perhaps to TP DXers dreaming of targets. Even when filled with 4 “C” batteries, the radio is remarkably lightweight (1 kg).
Dis-assembly reveals circuit components very similar to the 2010, and the top edge even has the 2010’s shiny metal strip. The radio measures 10.25 x 5.5 x 2.25 inches, or 260 x 145 x 58 mm. As opposed to the S5’s green and red LED tuning display, the EX5 has a single red LED to indicate station tuning.
The LED generally lights at the same signal level as the S5’s red LED. Competitive Testing The EX5 model was tested against three other Sony portable radio designs, for daytime ground wave weak-signal sensitivity, selectivity, image rejection, synch detector operation, and audio quality. To the maximum extent, all units were checked for normal operation, prior to the tests. The other units were all stock examples of the ICF-S5W, ICF-2010, and ICF-SW7600GR models. All the testing was done using live signals in side by side tests, without resorting to instruments. Three relatively weak signals were tested, one at the lower end of the band (KONA-610), one in the middle (CFAX-1070), and one at the high end (KDZR-1640).
Selectivity was tested by checking fringe KPQ-560 in the shadow of local KVI-570 (perpendicular), and by checking fringe CHMJ-730 adjacent to local KIRO-710 (both from the north). Image frequencies were checked from very strong local KSUH-1450 (on 540 KHz), and spurious products were also checked, adjacent to this local pest. As this was strictly a competition between stock units, no attempt was made to connect an external antenna to any of the radios, so that the test data would be entirely based upon the internal circuitry. Neither was any attempt made to test the radios in an optimal DX location—they were all compared in a typical suburban environment, the Puyallup River valley, 40 miles south of Seattle, Washington. EX5 vs. S5W These two sibling designs have very much in common, since the EX5 is the Japanese-market replacement for the S5.
Weak-signal sensitivity reception was absolutely equal on KONA-610 and CFAX-1070, with the EX5 showing a very slight sensitivity advantage on KDZR-1640. However, for all practical purposes, there was no clear “winner” in this comparison, and any difference one may note is more likely due to individual alignment and/or component differences, rather than any circuit superiority. Selectivity of the two designs is also remarkably similar, with both radios able to solidly receive KPQ-560 in the null of KVI-570, and CHMJ-730 adjacent to KIRO-710.
However, in this comparison, the EX5’s synch detector was effective in reducing remaining splatter from the locals, giving it a significant advantage in listening quality (the S5W has no synch detector). Image frequency reception was the primary criticism directed against the S5W, so I was curious to see how the EX5’s double conversion circuitry would address the problem.
The S5W has a strong image on 540 from KSUH-1450 (enough to light the red LED in the tuning display). The EX5 has the same image on 540, but its strength is reduced by about half, so that it no longer sounds like a “local.”
Further investigating the image matter, the S5W has a moderate image on 650 from KZIZ-1560 (in the null of CISL), but the image is almost inaudible on the EX5. In summary, there is a significant reduction of the problem on the EX5, but not a total solution. The S5W has excellent audio for a portable, easily the best of any of these receivers.
It has a relatively powerful speaker with good bass reproduction, and a continuously variable tone control.
In this respect, the EX5, with its single-switch tone control and less robust speaker, comes up short by comparison. Its audio quality is fully adequate for DXing and pleasant listening, but not in the same league as the S5W. EX5 vs. 2010 Obviously, the 2010 is an outstanding receiver, and has a wide range of functions that the analog EX5 cannot hope to emulate. But in a simple test of weak-signal sensitivity, the EX5 was more than a match for the 2010.
In reception of the 3 weak signal stations, the EX5 (and its sibling, the S5W) consistently had a moderate but definite advantage in audio strength and quality over the 2010. KONA-610 and KDZR-1640 typically fade in and out here in the daytime, but the EX5 was always first to make the signals readable, and last to lose them to fades.
CFAX-1070, by comparison, has a steady weak signal, but the EX5 usually makes the audio perfectly readable, in comparison to the 2010’s problematic reception. In selectivity tests, however, the 2010’s stock narrow filter was a significant advantage in reducing local splatter. The reception of KPQ-560 was basically equal, with the synch detectors operating in a similar fashion (the sideband is manually switched on the EX5, however, and there is no LED to indicate lock).
The EX5’s synch detector, when locked, was quite effective, although it requires somewhat more careful tuning than does the 2010’s circuit. CHMJ-730 has unavoidable splatter from KIRO-710, but the 2010’s narrow filter, in conjunction with the synch detector, made the splatter a little more tolerable than on the EX5.
With the exception of the 2010’s narrow filter, however, basic selectivity of the two radios is very similar. As mentioned earlier, since the EX5 has a minor image frequency issue, I was curious to compare this aspect with the 2010. The 2010 has absolutely no image of KSUH-1450 on 540 (or any other images), but it does suffer from spurious products on 1425 and 1475 (moderate strength), and on 600 (weak strength), none of which show up on the EX5. So, in judging the units’ ability to reject image and spurious products, one could conclude that they are roughly similar. Audio quality is another quite similar comparison.
Neither of these radios will ever win audio awards, but the 2010’s larger speaker and more powerful audio circuitry give it a slight edge. Both are fully functional for pleasant DX and local reception, however. EX5 vs. SW7600GR Again, the SW7600GR is a great value as a shortwave portable, and has many digital functions that the analog EX5 cannot match. But since both of these units retail for about $160, this comparison should be particularly interesting to medium-wave enthusiasts searching for an inexpensive first receiver.
Sensitivity tests on the three weak-signal stations revealed the EX5 as having a definite advantage, to a slightly greater degree than with the 2010. Before the fade-prone signals of KONA-610 and KDZR-1640 were audible on the SW7600GR, they were already easily readable on the EX5. CFAX-1070 was always perfectly readable on the EX5, but was close to the SW7600GR’s noise level.
The SW7600GR’s unique synch detector circuit was switched on to assist in reception quality, and it did make a noticeable difference in readability, although not enough to bring it close to the EX5’s reception level. In the selectivity tests, the SW7600GR had problematic reception of KPQ-560 in KVI-570’s null, but this was probably due to a sensitivity limitation, in my opinion. The CHMJ-730 test was much more competitive, with both the SW7600GR and EX5 limiting KIRO’s splatter to a similar degree.
With the two synch detectors switched on, the SW7600GR and EX5 can both eliminate most of the splatter, but as with the 2010, the EX5’s synch circuit requires more careful tuning than does that of the SW7600GR.
Overall, however, selectivity of the two designs is very similar, since neither has a narrow filter.
The EX5’s image frequency rejection has already been thoroughly reported, but tests revealed that the SW7600GR also had a strong KSUH-1450 image on 540, a moderate KZIZ-1560 image on 650, as well as a moderate KSUH spurious signal on 600, which the EX5 did not have. In this respect, it must be said that the EX5 has a slight edge in image and spurious signal rejection. As with the 2010, the audio of neither of these receivers will come close to high fidelity, but since the EX5’s speaker and audio are slightly more powerful, it must be given the edge in this aspect.
Verdict - The ICF-EX5 was never designed to compete with the multi-function digital shortwave receivers. For 22 years, it has excelled in the tough Japanese market for one simple reason: it delivers excellent value as a highly sensitive and selective medium-wave portable. Because of its lightweight portability and relatively low price, it is the receiver of choice for many Japanese medium-wave enthusiasts (which, incidentally, comprise a larger market share in Japan than they do in North America).
All of the tested receivers are common in Japan, and the Japanese themselves have run similar comparison tests (posted on the web), generally confirming my own results. Despite this, the analog ICF-EX5 is obviously not suitable for everybody. Lacking digital readout, a BFO, and memories, it is certainly not a logical choice for transoceanic DX.
Despite complete disassembly of the radio, I have yet to find adjustments that would extend frequency coverage to 1700 (the stock circuit will go up to 1640). And if you dislike the idea of analog tuning, or cannot live without memories, you will probably dislike the ICF-EX5.
However, for medium-wave DXers primarily interested in domestic (or Western Hemisphere) DX, at a price of $173 delivered, the radio certainly provides tremendous value for those interested in high sensitivity, selectivity, and portability.
At 1 kg (2.2 pounds), it is a logical choice for a high-performance travel portable. And for those who have always wanted an ICF-S5W, but don’t wish to pay $250 or more for a rare decent unit on eBay, this is a chance to obtain a new sibling unit with significant improvements, all at a lower price.
Supply Sources - To assist those interested in purchasing an ICF-EX5, I have investigated three possible sources, and have placed orders with two of them.
Audio Cubes (http://www.audiocubes.com) has the radios in stock, and offers them at a price of $173.00 US delivered ($159.00 plus $14.00 for EMS shipping). I placed an order with this company. They have my highest recommendation. My radio arrived within 2 weeks, well-packed, and with good communication throughout the entire process. Audio Cubes, in Osaka, Japan, allows you to pay with PayPal, credit cards, money orders, wire transfers, or even personal checks. The Audio Cubes website also has extensive information, in English, about the ICF-EX5, including a nice photograph.
Nichiei Musen Company (http://www.nichiei-musen.co.jp) can special order the radio for you, and quoted a price of $184.00 US delivered ($159.00 plus $25.00 for EMS shipping). Despite their website claims, however, the only form of payment they would accept was a bank wire transfer, which typically entails a $25.00 fee here in the U.S. Because of this, and because of an unclear warranty policy for service and repair, I did not place an order with them.
Japan Direct Company (http://www.japan-direct.com) can also special order the units for you, and offers extremely fast shipping (within 1 week). Unfortunately, this comes at a high price: $265.00 US delivered ($222.00 plus $43.00 for shipping, handling and insurance).
Thinking that some readers might wish to go this route, I placed an order with them. It was not a wise decision. My radio did indeed arrive within a week, but inside a shopping bag (apparently as a customs dodge), and had alignment problems (probably due to the rough transoceanic trip).
My experiences with Japan Direct could fill an entire page, but I will spare you the unpleasant details, and simply say that after payment of an additional $70 for postage both ways, I had a replacement radio equal in performance to the one from Audio Cubes. Readers are free to draw their own conclusions.
Disclaimers - Although this review of the ICF-EX5 was done with the utmost effort for accuracy, it is not possible to please everyone, when radios are directly compared. I am fully aware that proponents of other portables may not readily accept the result and that is understandable. There has always been a controversy about which portable is best for medium-wave DX, and my own subjective opinion is that all of the tested units have a claim for the title—in their own way. For the skeptics, I can only recommend that they withhold judgment until they actually test an ICF-EX5 next to their favorite portable, and then make a reasonable conclusion.
After all, at a price of $173.00 delivered, it is within financial reach of most of us. Finally, I should state that I have no financial connection to Sony, Audio Cubes, or any other company mentioned in this review, and that if my review has disturbed preconceived notions of receiver superiority, I offer my sincere apology. On the other hand, if you agree with my conclusions and find this review useful, I am more than willing to assume all the credit