U


REDSUN
RP2100


A new name in the World Band Radio arena is Redsun Electronics of China. Their new line includes two models currently available: the RP-2100 reviewed here, currently selling on eBay from China at just under $57.00 plus $38 shipping for a total of about $95 delivered to the US. Redsun also offers the RF-1210 analog at about $50 delivered.

The RP-2100 has been the subject of much speculation as a potential candidate to unseat the Eton S-350DL/Tecsun BCL3000 radios from their position of pre-eminence in the world of approximately $100, high performance, lunchbox sized multi-band portables. Is the RP-2100 a "better radio" than the S-350DL? And if so, does it sacrifice anything along the way? Finally, how does it compare with other reference portables at various price points and with varying strengths and weaknesses? Hold tight…I've just spent the better part of a month comparing the Redsun with the Eton S-350DL and original S-350 versions, the Eton E-1, E-5, a Panasonic RF-2200 and a GE Superadio SRII & SRIII. I also compared it with several other portables I had at my disposal to satisfy my own curiosity and feel these comparisons will paint a clear picture of where the RP-2100 shines and where it could benefit from a bit of minor tweaking on Redsun's part to be all it could be. The results are interesting to say the least.

Let me urge two cautions. Initial experiences can be misleading with the RP-2100 until you learn its personality…especially with the Chinese lettering it takes some time to learn all the control functions. Also, this radio is from an initial production run…one of the very first production units to become available. It is entirely possible and even likely that Redsun will make minor improvements and updates as they go along. This has generally been the case with world band portables by all manufacturers. Also, other Chinese manufacturers such as Degen and Tecsun seem to constantly evolve their product much as computer software never stops being updated. Other Degens and Tecsun's show continuing improvements throughout their production and there is every reason to think Redsun could act similarly. At this early stage this is pure conjecture and I didn't find any outright flaws that need to be addressed…just a few areas where things could be made a bit better with seemingly small improvements. I will explain as we go along.

DESCRIPTION

The Redsun RP-2100 is a large multi-band portable measuring approximately 11 ½" x 7 ¼" x 2 ¾", or 290 mm x 185 mm x 70 mm. It is in the same general size category as the Eton S350DL and E-1 radios which is my favorite size for an around-the-house portable radio. They're small enough to be easy to move about yet large enough to offer good RF performance, good sound and be easy to use.

The RP-2100 is PLL tuned covering: FM: 87.00 - 108.00 MHz
MW: 522-1620 or 1710 KHz/9 or 10 KHz steps
SW 1: 1711 - 10010 KHz
SW 2: 9990 - 20010 KHz
SW 3: 19990 - 29999 KHz
50 Presets are available with 10 in each band

Dual Conversion on AM and SW

Two IF Bandwidths: Nominally 6 KHz and 3 KHz

Audio Power Output 2.5 Watts on AC Power

Power Supply: AC 220Volt Input
DC 6 - 9 Volt center negative
4 D Cells or 4 AA Cells (switch selectable)
Built-In Charger

I.F. Output Jack (an outboard SSB adapter is said to be forthcoming) - I will report on it as an addendum at that time

Stereo Headphone Jack

Stereo Line Out Jacks (Dual RCA Type)

Controls: The RP2100 is well laid out. It is labeled mostly in Chinese…the translated English Manual available from Liypn on eBay:

V-COM-COLLECTIONS

makes initial operation much easier, not only by providing translations of all the knob markings but with descriptions of some controls whose use isn't immediately obvious.

I have also discovered that English-labeled RP2100's are available from Tquchina:

RADIO-AND-COMPONENT

* See end note about buying Chinese radios thorugh eBay:


The roomy front panel contains the large Tuning knob, to its left are the mode and band selector knobs with the Volume Control at the bottom. The smaller knobs at the lower left are RF Gain, Treble and Bass, and a 1/8" Stereo mini jack for headphones is at the far lower left.

Above the Tuning Knob are three push buttons for: Stop (a tuning lock), Slow and Fast tuning. To the right a group of 8 pushbuttons control Down & Up Tuning/Seeking, Memory, Alarm, Timers 1 & 2, Q. Tune and Preset buttons. The Q. Tune button is important and will be described in a moment. At the top right are three buttons for Power/Sleep, Local/World Time and Lock which disables all functions except the Light Switch. You can display World or Local Time momentarily while the radio is on.

On the top panel are a Light Switch (which can turn the lights on for 8 seconds or lock them on) and a Snooze Bar.

The left side contains RCA Stereo Line Out jacks, Battery Size Selector, DC and AC Power in jacks. The right side contains switches for Button lights, DX/Local and Internal/External Antennas. The Button Lights switch allows the pushbuttons to also illuminate when the dial light is on, evidently a power saving feature.

The back panel contains two Pal Connectors: One an external FM/SW antenna input, the other an AM IF Output jack for future connection to an outboard SSB or DRM decoder, and spring loaded connectors for a MW (AM) antenna. Inside the battery compartment which will let you load 4 AA and 4 D cells (simultaneously if you wish), is the 9/10 KHz MW Step switch.

Basic Operation & Initial Impressions: The RP2100 is a fun radio to use after a short time spent getting to know it. The high points are: excellent RF performance on all bands, excellent sound, solid feel and decent, although not superlative, tuning via the knob. It has a neat looking handle which reminds me of the Grundig Satellit 700's handle…attractive and it folds away to nothing. It was immediately apparent that reception was sensitive and strong, and the audio likewise impressed me immediately. Compared with my other similarly-sized radios the Redsun offers a full, warm sound with plenty of audio punch and excellent clarity. It's rated at 2.5 watts on AC power…even if it's half that on battery power, it is enough to fill a large room authoritatively and pleasantly. It sounds better than my Eton S350DL or E-1…the only portables I have which sound better are the Superadio series, but the Redsun is closer than any other contender in a similarly-sized radio. The two IF bandwidths are given as 6 KHz and 3 KHz and appear to be well-chosen for program listening. The Wide mode is fairly wide…it lets stronger AM/SW signals retain a natural sounding clarity, while the Narrow filter similarly seems well chosen to eliminate interference under most conditions while maintaining as much clarity as possible. When the Wide filter is too wide, usually at night when there are many adjacent signals, I find I can still get excellent results using the Narrow setting and off-tuning by 1 or 2 KHz. It works well.

I also noted excellent AGC range…as I tuned weak signals on the S350DL and RP2100, the weaker signals maintained their full volume on the Redsun while I had to advance the volume a bit on the S350DL to match it. The eventual reception was actually not very different, but the superior AGC range of the Redsun made it seem more sensitive. I also have to say that comparing my S350DL with the Redsun, the Redsun was decidedly easier to tune on SW…the '350 is just more finicky to get it tuned just right…the Redsun locks onto, say 9515 and stays there. By comparison the S350 series are much fussier to tune on SW than they are on AM and FM.

However, the radio is not without its quirks…here are a few I have noticed.

Tuning: The RP2100 is unique in that it is a PLL design (digitally tuned), yet it has no keypad for Direct Frequency entry. This seems like a serious omission in a day where PLL portables with keypads are common. Also, the RP2100's 50 Memory positions are limited to 10 presets per band. Maybe not a problem to someone like me who uses memories only for a few stations, but curious given the fact that lesser radios offer hundreds of memories these days.

However, a quick look at the pictures of the vintage Panasonic RF-2200 and the Grundig/Eton S-350 series radios reveals the concept of the Redsun: to mimic the operation of these analog receivers but with digital technology for consistency and accuracy, while maintaining a top level of overall RF and audio performance. The design makes perfect sense when looked at in that light.

The Redsun divides the SW spectrum into three bands, SW 1, SW 2 and SW 3, similarly to those analog radios. But with no keypad it takes about 20 seconds to twist the dial from one end of a band to the other and that is distinctly unpleasant. The encoder circuit itself sets this "speed limit;" that is, you can spin the knob faster than the encoder can take the input, so it stops advancing. You soon learn what the maximum speed for the knob is. However, you can navigate quickly with the "Q. Tune" button, which is not explained well in the manual. "Q. Tune" (Quick Tune) allows you to step through SW bands. So if, for example, you're on SW 1 (1711 - 10010 KHz), pressing "Q. Tune" steps you sequentially through 2250, 3150, 3850, 4700, 5800, 7100, and 9400 KHz, the nominal starting points of the 120 meter through 31 meter bands. It performs similar duty on SW 2 & 3 as well as AM and FM where it steps you through 100 KHz AM and 1 MHz FM. This eliminates the need for heavy duty knob spinning and becomes natural after a short period of use. The tuning action via the knob is not quite noise-free. It is mute-free which means you can tune without fear of missing anything, but there are some spurious noises while tuning that I wish weren't there. However, overall the set has a nice feel when you are scanning within bands…the two tuning speeds seem about right and final tuning, with its PLL accuracy, is infinitely easier than on its analog predecessors. Also note that as battery level drops almost to the point where the unit shuts off, just before that point the tuning becomes a bit touchier. I wondered what was going on at which point it switched off due to low battery. I don't consider this to be an issue but it's worth noting.

Another feature not possible on the analog-tuned S-350 or RF-2200 is that each band (AM/FM/SW1/ SW2/SW3 "remembers" where you were last tuned within that band, so you can be listening to your local AM station on 600, tune away to check out some shortwave on another band, but when you switch back to AM the Redsun will be right where you left it on 600 KHz…this is very handy and is a nice feature of the RP2100.

The push buttons require solid pushes. Interestingly, they are clicky buttons, but the click does not necessarily indicate that the switch has been activated. If you don't hold the button for just a split second, it won't actuate, although you will still hear and feel the click. Not a biggie - the delay seems to be in the software itself rather than in the switches and affects every front panel switch identically. It's not a problem once you get used to it, but quick taps on the switches will be ignored.

FM Stereo/Mono: The RP2100 delivers Stereo FM at the Headphone and Line Out jacks. But there is an oddity. Be sure to keep the FM Stereo/Mono switch in Mono at all times when using the radio with its built-in speaker. If you leave the radio in Stereo you will hear only Right Channel audio from the speaker…normally you would hear a mono mix of the two channels, but the RP-2100 does not do this. You will also not get the improved reception mono mode often provides when signals are less than perfect, so be sure you keep the switch in Mono. Again, it's not a problem as long as you're aware of it, but it is odd.

Illumination: I have to say the lighting is dim and a bit unusual. First there are two buttons for controlling the lighting; the "Button Light Switch" which enables or disables the Button Lights…this seems superfluous. Additionally the main "Light Switch" on the top operates somewhat like the original S-350/BCL2000 series switches did, which means if you lock the lights "ON", they will stay on, even after you turn the radio off. (Newer S-350's turn the lighting off when the radio goes off). One oddity though. If you lock the lights "On", they only stay on until you operate any of the controls…then they revert to the 8 second on/auto off mode…kind of annoying. Unfortunately, the dial lighting is also rather dim, making it hard sometimes to tell whether they are on or off under typical room lighting. Several times I have returned to the radio to find I left the lights on…I never did this with my other radios with similar arrangements. The S-350DL display lighting is much brighter and really stands out compared with the Redsun's display. I do like the Redsun's lighted buttons though.

Battery Level Indication: The Redsun can operate on either AA or D cells. I only tested them on AA cells as I was comparing three samples together. I noted that the level indication is conservative to say the lest. T-It is a 3 segment meter, and the third segment drops out almost immediately, at least on AA cells. Again, not a big problem…with any radio one must learn the characteristics of the metering, but I would judge this meter to read a bit lower than reality. All three samples I have are identical in this regard.

PERFORAMANCE COMPARISONS

I ran several comparisons with various other radios to give an overall impression of how the RP2100 performs. All tests were done with fresh batteries and built-in antennas only. The RP2100 acquitted itself very well overall.

First test: Redsun RP2100 versus Eton S-350DL and Eton E-5.

With all the comments on the internet as to whether or not the Redsun succeeds where the S350 series fails I had to compare these two radios first thing. I added the E-5 because it is presently one of the most sensitive radios in its size class, although it retails for around $150 so I wanted to see how it might compare with these larger yet less expensive portables.

AM Reception: The Redsun demonstrated virtually identical sensitivity and selectivity compared with the S-350DL. Again, the Redsun's superior AGC makes it seem more sensitive because weaker signals maintain the same volume as the strongest signals, while they are a bit quieter on the S350, but when you turn up the volume on the S350 to compensate, the resulting reception is the same. This is a point easily missed when comparing radios. The E-5 was definitely a notch lower in AM sensitivity…the weak signals were not only lower in volume but also had a higher noise level. You can also note some asymmetry in the IF filters of these radios…that is to be expected at this price point. This is most noticeable when center tuning on a given frequency seems a bit different in Wide mode than in Narrow. Botht he Redsun and Eton S-350 show some error when center tuning by ear…not a big issue, just something to be aware of. But in general, the Wide and Narrow IF bandwidths of each of these radios seemed totally reasonable and useful. It was a bit more finicky to tune the S-350 and S-350DL than either of the digitally-tuned sets, but again, on AM the S-350's tuning is not hard to live with at all. It's a bit more touchy on SW as you would expect.

SW Reception: Here there were a few variations from one frequency to the next. I checked several weak to medium strength signals across the SW spectrum. The RP2100 sometimes outpulled both the S-350 and the E-5 noticeably, but on other signals they were virtually identical. Also, the S-350 outperformed the E-5 on 6070 KHz but the reverse was true at 10,000, but in general the RP2100 was the clear winner in this test. Most weak signals sounded best on the Redsun…full audio levels and the lowest background noise. This is one sensitive SW portable.

Also since the S-350 is the only single conversion radio in this comparison, it does suffer from images which the dual conversion Redsun and Eton E-5 do not. This manifests itself as out-of-band images of signals where they should not appear. Potentially these images can interfere with a desired signal, although generally they seem to be most noticeable when tuning between bands - they do not generally ruin reception of the major international broadcasters. It is important to note that the RP2100 eliminates the images without sacrificing sensitivity which is sometimes the case with less efficient dual conversion designs.

FM Reception: Here again the Redsun excelled. In my suburban location the FM dial is crowded and the number of stations I can receive is often more a matter of selectivity than sensitivity. However there are some out of town signals which are at the threshold of audibility which is a good test for pure sensitivity. The RP2100 was the best of this group on both counts. The E-5 was second and the S-350 the least sensitive or selective. The Redsun seemed to be able to deliver more clean signals with no noise or interference problems.

Second test: Redsun RP2100 versus Eton E-1. Admittedly an odd combo to compare…the E-1 sells for $500 and is loaded with performance-enhancing and convenience features not found on the Redsun RP2100 - they simply are a different class of receiver. However, I was curious to see how they might compare on the basic parameters of performance: whip sensitivity, sound quality and general ease of use. It seemed fair and I was surprised at what I found.

On SW the Redsun was noticeably more sensitive than the E-1. Many signals had a quieter noise floor and greater apparent sensitivity. On AM the comparison changed depending on the ambient RF noise levels. Inside my home, with typical levels of background noise, the Redsun was decidedly better on AM…the E1's whip antenna received considerably more interference making weaker signals unpleasant to listen to. However, outside on the deck where the noise was gone, the E-1 proved itself to be slightly more sensitive on AM then the Redsun…weak and medium strength daytime signals from 100 or more miles away had a quieter noise floor on the E-1…it's AM is great off the whip when there is little RF interference. Incidentally, I noticed that the E-1 emits some RF interference of its own which I could hear on the Redsun until I separated them by about 2 feet.

The Redsun also proved to have better audio than the E-1. Although I like the sound of the E-1, the RP2100 has a wider frequency response, with more warmth and impact to the sound. And of course, the Redsun also has a handle, making it far easier to carry around than the E-1 which lacks one. Hmmm.

Please don't construe this to mean the Redsun is overall a better radio than the E-1…that is not my feeling at all. The E-1 excels at virtually every other measure of performance in areas such as dynamic range/overload rejection, filter symmetry and shape, tuning ease and accuracy, memory capacity and organization, SSB, synchronous detection, passband tuning, XM Satellite capability and on and on and on. In many cases the E1 will deal with hard to hear signals far more effectively rendering many signals clearly you will not be able to hear on the Redsun, especially with external antennas. But be aware that for conventional listening off the built-in antennas, the Redsun has its own areas of superiority and that alone is amazing given the price differential separating these two.

AM Reception versus the GR SR II, SR III, & Panasonic RF-2200: The GE SR's and Panasonic RF-2200 are among the hottest of all AM portables ever made. They also have very big sound for their size, which is a bit larger than the other radios we've been talking about here. I found the Redsun was every bit the equal of the SR III and only a hair less sensitive than the venerable SRII and RF-2200. Those two radios provided a slightly lower noise floor on weak to medium strength signals, but still this is excellent AM performance. The Redsun also gives you the benefits of two IF bandwidths and digital accuracy so no apologies for AM performance are needed…the Redsun is only one notch below these highly respected radios on the AM band which means it is better than most of what's out there.

Quality Control: I was fortunate to have three samples at my disposal to compare for uniformity. I am glad to report that I could determine absolutely no operational differences among them which is outstanding in this class of equipment. Down to the tiniest details they all operated identically and this is encouraging, especially for a first production run of a new company's very first model…outstanding!

CONCLUSIONS
Redsun has burst upon the World Band Portable scene in a very positive way with their new RP2100. This radio offers absolutely superb overall performance within the limitations I've explained for under $100 delivered from China. It offers powerful audio, great RF sensitivity on all bands, two well-chosen bandwidths for AM and SW, a convenient handle, many power options, a feel of solidity and quality and fairly simple operation once you get used to it.

Negatives include lack of a keypad for direct frequency access, dim and awkward to use illumination, the FM Mono issue and some spurious noises when tuning via the knob. Eliminating the last vestiges of those noises would go a long way to increasing the enjoyment of this radio. It is very possible that future production runs may address some of these issues. It would also be nice to see a US Import version with a 120 Volt AC Input and a US warranty.

So…is the Redsun RP2100 everything the Eton/Grundig S-350 series is not? In many ways, yes it is - no drift, easier tuning, better SW sensitivity, better AGC and slightly bigger sounding audio. The latest S-350 radios offer a slightly controversial "Tuning Lock" circuit which does reduce drifting compared with earlier versions but also gives up some of the naturalness of analog tuning, because you often find the lock circuit fighting you as you try to make minor tuning corrections. Some users prefer the earlier models without the lock. The S-350 series does offer styling some may prefer to the Redsun which although pleasing to me does look somehow less sleek than the S-350DL. The S-350DL also offers a much brighter, snappier looking LCD display and illumination along with true analog tuning which eliminates the spurious noises you hear when tuning the Redsun and that alone can be very important to some users. So I'm not going to throw out my S-350 yet. To S-350 or S-350DDL owners who may be wondering if it is a worthwhile upgrade to grab a Redsun I've got to say it depends on how much you like radios and are willing to own several to suit your whims. Performance differences are not so night and day that it obsoletes the S-350, but the Redsun does make real improvements in just about every area of performance, most notably SW sensitivity and ease of tuning. Whether or not they justify purchasing another radio… that choice will be up to you.

And to the folks at Redsun, a great big, "Thank You" and "Way To Go Guys!!!" Your first radio is a winner.

Comments or questions? Email me at jay@radiointel.com

Jay Allen


*End Note: Buying Chinese Radios Through eBay:

Both of the eBay sellers I mentioned earlier are highly reliable; I have purchased many radios this way and have never had any problems. There are a few things you should be aware of however.

First, these radios require 220 volts for AC operation. You can use a 120 volt to 220 volt step-up transformer which these sellers can provide…for ultimate peace of mind you could obtain one locally to get one with UL approval. Or you could use an external wall wart…the Redsun has a DC input jack for this.

Perhaps more importantly however is that you do not get a US Warranty. In the relatively unlikely event you do receive a defective unit (I have gotten one sub-standard sample out of about 30 radios purchased this way), you would have to pay to ship it back to China for a replacement…either that or chalk it up to bad luck and purchase another…which decision is most valid depends on the price of the radio. These radios cost about $55 and shipping with insurance is about $40. In this case it would cost you about $38 to return the radio for replacement assuming the seller would pay to ship the replacement to you, so it's worth it. Remember: when and if these Chinese radios are eventually imported officially by a US Distributor (not all of them are) you can expect to pay roughly twice as much to get that US Warranty. At this moment no one knows if the Redsun will be imported to the US or not.

 

Chinese vs English


Above photo courtesy of Fernando @ Fenu-Radio.ch

 

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