- Category: Our Stuff
- Published: Wednesday, 28 November 2007 10:46
- Written by Gary DeBock
- Hits: 37717
A Supreme MW-DX Overachiever (by Gary DeBock)
It is an AM-FM Stereo portable with included headphones, having an AM section so sensitive and selective that it is capable of TP reception… all for a price of about $16.00? Is this possible in today’s inflated marketplace, where many manufacturers seem to have forgotten the concept of superior AM performance? The answer is a resounding, “Yes!”
Introduction The Sony SRF-59 is a very small portable that could easily be mistaken for a child’s disposable toy. Having no speaker, and with the included FM stereo circuitry and headphones, one could easily get the impression that Sony’s design effort was concentrated on the FM side, to the detriment of AM. Even if not, how much performance can medium-wave DXers expect from such a small and inexpensive analog portable? An incredible amount, actually. Sony has packed an amazingly sensitive and selective design into the tiny SRF-59, which not only tunes the entire (530-1700 kHz) AM band with pleasing audio and AGC action, but does so with remarkable freedom from image and spurious signals (the bane of most inexpensive portables). Regardless of the added benefits of portability and price, such a rare combination deserves praise, in the reviewer’s opinion.
Construction Physically, at 65 x 93 x 26.5 mm (about 3 x 4 x 1 inches) the SRF-59 will easily fit into a shirt pocket, and partly due to the lack of a speaker, weight is a miniscule 84 g (3 ounces). It comes in an attractive silver and gray-colored plastic case with a blue analog dial, very similar to the transistor portables most of us grew up with in the pre-digital age (except perhaps for the “17” at the right of the AM dial). Controls are very basic, with only two thumbwheel controls for tuning and volume (AM) and sensitivity switch (FM only). Except for the on-off and AM-FM switches, that’s it! Having no speaker, the SRF-59 has a stereo headphone mini-jack at the top of its case, and includes a basic set of stereo headphones (acceptable for MW DXing, but not recommended for FM stereo enthusiasts). Although this review will focus on the AM performance, the set’s stereo FM performance is also commendable, with the headphone wire serving as an external antenna. The FM reception is adequate (as long as the headphone wire is oriented properly), but would not satisfy a demanding FM DXer. The set runs on a single AA battery (not included), which is covered by a hinged door at the lower part of the rear case. User reports (on Amazon) indicate that this battery has excellent run time, no doubt due to the lack of a speaker. Finally, a plastic belt clip is included, which attaches to the rear of the case.
Circuitry Disassembly of the compact SRF-59 is not recommended, but for the purpose of this review, it was absolutely necessary. After removal of the two screws and careful separation of the front and back, it was discovered that such separation will disconnect the geared plastic linkage between the tuner and the orange tuning dial needle, leaving the dial pointer linkage loose, in the front case slot. This is not a fatal problem, but it should be enough to deter all but the most curious hobbyists (like the reviewer) from attempting such disassembly. The circuit board assembly, attached to the rear case, has a 1.75 inch ferrite bar antenna, a band pass filter (presumably for AM, because of proximity to the ferrite bar), and other discrete components (not surface-mount construction, a big surprise). Sony’s famous proprietary IC chip (presumably the reason for the amazing AM performance) is hidden on the bottom of the circuit board, forcing the radio hobbyist to wrestle the glued circuit board upward from the back plastic case and peek underneath, before this important discovery can be made. There are actually two IC’s on the bottom of the circuit board-- the second is presumed to be a small AF amplifier chip. Finally, for those like the reviewer who must reassemble the unit, the trick is to engage the tuner’s gear wheel with the dial needle’s plastic geared linkage… definitely easier said than done, because of the radio’s tight fit, and the need to exactly match the dial and tuner frequencies.
Performance Any doubts that the SRF-59 is a serious AM performer will be quickly dispelled, once fringe reception is attempted. Daytime MW-DX performance of the SRF-59 is nothing short of astonishing, with not only the usual weak-signal stations having solid audio, but even the toughest portable catches being possible. In the reviewer’s typical suburban environment of Puyallup, Washington (having numerous Seattle semi-locals but only three strong locals within 5 miles), the unit not only easily receives the typical fringe test stations of KONA-610 (160 miles), CFAX-1070 (110 miles) and KDZR-1640 (120 miles) at high noon, but in the somewhat enhanced November conditions occasionally prevailing, has received noontime audio fading in and out from KNRO-1670 (440 miles) and mumbling 1:00PM audio from KFBK-1530 (580 miles).
Competitive Testing Although the SRF-59 will be one of four “Mighty Mite” radios competitively tested in an upcoming “shootout,” for the purpose of this stand-alone review, it will be compared to the reviewer’s ICF-2010, ICF-SW7600GR, and ICF-S5W units. This is not to imply that the tiny Walkman is a suitable substitute for any of these fine receivers; indeed, the SRF-59 has its own unique issues, as detailed in “Wish List” below. But as a simple yardstick of the Walkman’s sensitivity, selectivity, and rejection of unwanted images and birdies, it is hoped that such direct comparison will assist the reader in accurately judging the performance capabilities of this tiny portable.
In extensive daytime sensitivity tests performed for the Sony ICF-EX5 review (kindly republished by Colin Newell on his excellent dxer.ca web site), it was determined that the ICF-S5W has a moderate sensitivity edge over the ICF-2010, which in turn has a moderate sensitivity edge over the ICF-SW7600GR (inclusive of synch detector function). These three highly respected receivers (all aligned and checked for proper operation) were used to measure the SRF-59’s relative performance at local noon on November 26, 2007, a day with somewhat below-average reception conditions. KONA-610: The SRF-59’s signal quality was clearly superior to that of the SW7600GR (with synch detector on). The Walkman had weak, mumbling audio, whereas the SW7600GR had only a carrier (on SSB), with no audio. When the SRF-59 was compared to the 2010, the 2010 and the tiny Walkman had roughly similar signal quality when the 2010’s synch detector was off (weak, mumbling audio), but the 2010 was clearly superior to the SRF-59 when the synch circuit was on (having steady weak audio). As expected, the S5W was again the most sensitive, with steady moderate audio.
CFAX-1070: This station provided only weak, mumbling audio on the SW7600GR (synch on), but the SRF-59 again showed its superior sensitivity by receiving steady weak audio. The Walkman and the synch-off 2010 again were almost identical with steady weak audio, the 2010 again needing the synch circuit to provide weak to moderate audio. The S5W had steady moderate audio. KDZR-1640: This station’s signal produced only a weak SSB carrier on the SW7600GR. The SRF-59 and the synch-less 2010 again deadlocked with weak mumbling audio, with the 2010 providing steady weak audio in the synch mode (identical to the S5W).
So to summarize the sensitivity tests, the SRF-59 was clearly more sensitive than the SW7600GR on all frequencies. Its sensitivity was roughly equivalent to the 2010’s as long as the synch detector was off, but was clearly inferior to the 2010’s with synch on. Since the reviewer was somewhat astonished at these results, a different 2010 was substituted during the competition with the Walkman, but the same results were obtained.
In the selectivity tests, the SRF-59 again proved it was competitive with the other receivers. The band-pass filter (described above) does a superlative job, proving every bit as effective as the S5W’s ceramic filter. Fringe CHMJ-730 can be heard with very little KIRO-710 splatter and KPQ-560 can easily be received in the null of KVI-570. Only the 2010’s combination of the narrow filter and synch detector was slightly more effective than the Walkman’s band-pass filter, in rejecting adjacent splatter.
The biggest surprise for the reviewer was the SRF-59’s almost total freedom from image and spurious signal reception. Very careful investigation from 530 to 1700 produced only a hint of a spurious whistle on 730 kHz; although it was so weak as to be negligible (this was in my moderate-RF suburban environment). By comparison, the SW7600GR has both image and spurious issues, and the S5W has a serious image issue. Even the 2010 has minor spurious problems (as documented in the EX5 review, which also details the image and spurious issues of the S5W and 7600GR), but Sony has apparently solved both kinds of problems, in this SRF-59. To tune from 530 to 1700 in a small portable and have almost total freedom from images and birdies is astonishing, regardless of price.
As mentioned previously, the Walkman’s audio comes only from headphones, so superb AGC performance is required to prevent sudden loud audio from irritating the searching DXer. Rest assured that Sony has accomplished this very well, with the combination of great AGC action, and pleasant audio. An upgrade in headphone quality will provide the user with even more pleasing audio and comfort, if desired.
TP-DXing with the SRF-59 The Walkman’s excellent sensitivity and selectivity make barefoot transoceanic reception quite possible, as the reviewer has discovered with loggings of JOAK-594, JOIB-747 and HLCA-972. However, these contacts are much more challenging (and exciting) than routine TP contacts. Success depends primarily on the operator’s attitude, his familiarity of “powerhouse” TP stations, and knowledge of propagation. Sheer luck also helps, as does a salt water location (the reviewer is 4 miles from salt-water Puget Sound). The analog SRF-59 has no digital frequency readout, SSB capability to check carriers, memories, or selectable filters. It has only a tuning control, and a volume control... and that’s it! In this medium-wave equivalent of ham radio’s QRP operation, the operator’s skill and determination must compensate for his extremely limited equipment. “Routine” TP contacts are no longer routine, and you must work hard for them! Sound interesting? For the reviewer, it has been a fascinating challenge.
For best results, my recommendation is to have a fully TP-capable receiver like the 2010, E1, R8 (or equivalent) to first “spot” powerhouse TP stations in the clear, during propagation peaks. When the audio of the TP station becomes sufficiently strong and QRM-free, the SRF-59 has a fighting chance to log it. Every experienced TP-DXer knows which “powerhouse” stations are likely to be strongest at his location—here, it is JOAK-594, and JOIB-774. I followed the above procedures to make these first two TP loggings, which were a great thrill on such a tiny radio! The logging of HLCA-972, however, was due more to sheer luck. I had never logged this station before on any receiver and during a propagation peak during the Asian sunset, the station suddenly faded in to a tremendous level on my 2010. At the peak of this fade-in, I urgently grabbed the SRF-59, hurriedly tuned to the right of KJR-950, and caught a trace of Korean, right before HLCA again faded away completely! The feeling of excitement and accomplishment was amazing, and it is the reviewer’s sincere hope that other TP-DXers (most of whom are far more experienced) will accept the challenge (and enjoy the satisfaction) of TP-DXing with this amazing portable.
Wish List As you may have guessed, the tiny SRF-59 is not quite perfect. Probably the biggest user complaint will be the somewhat touchy thumbwheel tuning control, which requires a very steady thumb for best results (especially at the top of the band). Aside from this, some users may dislike the lack of a speaker, and the analog design. For these DXers, Sony and other manufacturers have designed alternative digital radios similar to the SRF-59 (soon to be compared in a separate review). Indeed, for the Walkman’s basic DX performance, this reviewer cannot find any serious issues to criticize.
Verdict The SRF-59 Walkman provides an incredible value for the medium-wave DXer. Not only highly sensitive and selective, it also tunes the entire band with pleasing audio, great AGC, and almost total freedom from images and birdies. Such an accomplishment would be commendable in any portable, but when the price of $16.08 (Amazon) is considered, the value is astonishing. The SRF-59’s portability and versatility make it an obvious choice for casual DXers, as well as for serious DXers looking for new challenges. The reviewer has found the radio quite capable of barefoot TP reception, providing even the most experienced DXers with a new way to test their skill, patience, and knowledge of propagation. In summary, the SRF-59 is a quick ticket to fun, and an unbeatable value!
Best Wishes to All,
P.O. Box 1313
Puyallup, WA 98371
(The reviewer wishes to express sincere thanks to Nick Hall-Patch for his extensive advice and support, and to Colin Newell, for his suggestion of writing this review.)
Gary started serious BCB DXing as a 14-year old in Japan (military dependent in 1967), and enlisted in the Navy in 1971.
Gary was fortunate to not only receive intensive electronics training as a sonar repair technician, but also to have free travel to almost all of the countries we dxer's currently chase for TP contacts.
A fascination with Asian foreign languages led to a conversational ability in Japanese, and (after meeting a cute Hong Kong girl in 1980...) Cantonese.
That girl, Ruth, later became his wife, and now heads the Chinese TP Translation Service, providing translations of any unidentified Chinese audio clips for DXers.
After leaving the Navy in 1982, Gary has been a Washington State real estate broker and property manager, while maintaining his intense interest in DXing, radio tinkering and experimentation, foreign languages, and searching for the ultimate antenna acreage next to the ocean.