By Jason Reilly, VK7ZJA

 

It’s a sunny winter’s morning, and I’m enjoying a hot chocolate at my favourite café, when Mark the senior technician for a local radio broadcasting station arrives.  Mark tells me that one of the announcers at the radio station enjoys a spot of AM & FM broadcast band DX’ing, and has been impressed by the performance of a new radio that Jaycar has been selling, the AR1747.

I’m not generally known for being impulsive – normally I’m very careful, calculating and cautious.  Having recently purchased a Degen DE1103 receiver, I hardly needed a new one much the same.  For reasons that I still can’t explain to this day, it was only a matter of hours after that meeting with Mark that I too was the owner of an AR1747.

 

The AR1747 is sold in Australia by Jaycar Electronics for AUD $99.95, but is also sold as the Kaito KA2100 and Redsun RP2100 elsewhere in the world.  There has been some confusion on yahoo groups and other internet blog sites as to wether the AR1747 is indeed the same as the KA2100 or RP2100, or if it is the same as the slightly lesser specified KA2000 / RP2000.  Well I can definitely assure you that the AR1747 is in fact the same as the better equipped KA2100 / RP2100.  This receiver is made in China, and some versions that can be purchased on the internet have Chinese lettering, but the Jaycar offering comes with all English inscriptions, and perhaps more importantly for those nervous about making internet transactions, can be purchased at local retail outlets and come with a store-backed warranty.

The AR1747 is a moderately large portable radio, measuring 290mm wide, 185mm high and 70mm deep.  You’ve got several options for powering this radio – you can use 240 volt AC mains direct into the radio, or a 9 volt DC input.  If you want to use batteries, you can use either 4 x D size batteries, or 4 x AA batteries – either normal batteries, or rechargeable.  The AR1747 has the ability to charge the batteries, and this charging routine will turn off once the batteries are full or 12 hours has passed.

What can be heard on the AR1747?  The unit will tune 520 to 1710 kHz in 10 kHz steps or 522 to 1620 kHz in 9 kHz steps depending on what position you’ve selected on a switch within the battery compartment. There is also shortwave coverage from 1711 to 29999 kHz in 1 kHz steps in three ‘bands’ in AM only, and 87.0 to 108.0 MHz rounds out the FM broadcast band coverage.  In each band, there’s a ‘slow’ and ‘fast’ tuning step mode: for the AM broadcast band, in ‘fast’ mode this is either 9 or 10 kHz as indicated above, ‘slow’ will give you 1 kHz steps.  In the shortwave bands, these steps are 5 & 1 kHz, and in the FM broadcast band, you get 100 and 10 kHz.

 

Well, how about we take a look over this radio and see what it has in the way of user controls. This is quite a busy radio, even given its size. There is a 13 cm speaker which can be driven with a generous 2.5 watts of audio, and the resulting sound is very pleasing, no doubt partly due to the size of the speaker and cabinet. Beneath the speaker there is a 3.5mm headphone connector (yes, stereo output on FM broadcasts), an AM RF gain, Treble and Bass controls. Next to the speaker are three controls arranged vertically: an AM bandwidth control combined with a FM mono/stereo selector; a shortwave band selector; and a volume control. In the centre of this panel is a decent sized tuning dial, and just above it are three buttons that will lock the tuning dial, and select slow or fast tuning rates, as mentioned above. The other buttons on this panel activate several functions; we’ll take a look at those functions soon. Above the tuning dial panel is a very large display, which is very clear and easy to read. The display is backlit with a soft orange light, and the keys & buttons are backlit too, however the button backlights only activate with the press of one of those buttons - using the tuning dial or a tone control for example doesn't activate the key backlight, only the display backlight. This display has a signal strength meter which at first appears to be useless, spending a lot of its time indicating 4 out of 5 bars, in a normal suburban situation. However, once you get it into a quieter environment, well away from TVs and the switch-mode power supplies that seem to reside inside just about every domestic appliance these days, only then can you begin to appreciate how quiet the receiver in this radio can be. In contrast to this, the radio is anything but quiet as you tune the bands: when you get to a band edge, the radio issues a VERY LOUD “beep beep”, almost in an admonishing way, and irrespective of the volume setting. Thankfully, there is an undocumented feature that allows you to turn this ‘helpful’ facility off – with the radio off, hold the alarm button for 3 seconds.

 

Perhaps this comment about ‘undocumented’ feature isn’t quite true. The instruction manual would have to be one of the worst I’ve come across – it is very very hard to follow and understand. Another complaint with the radio is that there is no direct frequency entry available; the only apparent tuning option available is the large tuning knob. Or is it? The ‘Q.Tune’ button permits you to step through the band much faster than the tuning knob could ever do. Another feature not very well explained by the manual. It’s still not as convenient as direct frequency entry, but it does make life much easier, once you know about it. Speaking of the tuning knob, it has a definite resistance to it, and is a little too stiff for the finger indent in the tuning knob to use effectively. It is quite large and easy to use otherwise. While you use it, trundling though the bands, you will hear the radio make a ‘plink’ sound as you change frequency. It’s nothing that affects the reception capabilities of the radio, just a slight quirk that may become annoying over time.

 

Now, let’s get back to the other function buttons and what they do… At the top right, the most prominent button is the power on/off button, but tapped quickly twice will also activate the sleep function to automatically turn off the radio after a predetermined time. Directly underneath this is the W/L key which changes the time display (always shown when the radio is off) from local to world or UTC time display. And below that is the key lock button, which is standard fare these days. If you don’t like using a tuning knob, you also have the option of using the Up or Down keys to do the tuning for you. The Alarm key’s only function appears to be deactivate the silly little beeper circuitry. The Mem key is used to input frequencies to memory, and the Preset key recalls memories. The Preset key will also control the rechargeable battery charging circuit. The Q.Tune key steps through the bands at 100 kHz on the AM broadcast band, 1 MHz on the FM broadcast band, and will step to the beginning of common shortwave AM sub-segments used for broadcasting.

 

Common to all keys & buttons is a slight delay in their action. Rather than just a quick press or tap, each button needs to be held in for about half a second to activate – this takes quite some getting used to. The side panels are rather busy pieces of real estate too. On the left side, there’s a pair of line out connectors, a switch to select between AA or D size batteries, and the 9v DC and 240 v AC input jacks. The right side has a keylight switch (lights up the keys only), an attenuator for the AM & shortwave bands, and a switch to select either internal or external antenna connection. Let’s not forget the top panel with a snooze button and a display backlight. The rear panel is by comparison quite plain. There is a FM 75-ohm coaxial antenna socket, a 455 kHz IF output socket (for connecting an external SSB adaptor or a DRM decoder etc), a pair of spring-loaded AM high-impedance antenna input terminals, the battery compartment, and a nice fold-away carry handle that flips up too. You’ll also find the quite long telescopic rod antenna here too.

 

 

Comparison with the Degen DE1103:

 

Since I’ve recently done a review of the little wonder receiver by Degen, the DE1103, I thought it would be both fun and convenient to compare the two radios performance. You might think that the AR1747 being the much bigger radio it would automatically be a better radio, having more room to fit bigger & better components for example. But don’t be too sure, the little Degen has shown itself to be a surprisingly capable radio. In my review, I’d mentioned that the Degen had the most sensitive FM broadcast band receiver of any radio I’d ever used, so it’s going to be hard to beat on that aspect alone. For these tests, I was careful to try and level the playing field for each radio – using their own built in antennae, either the ferrite rod antenna for AM broadcast band, or the telescopic whip antenna for shortwave and FM, extended to the same length. Tests were also done with a common external antenna to see how each would handle that situation. I had also used a good pair of cover-the-ear headphones to gauge their individual audio characteristics, but I also didn’t ignore how each sounded on their own internal speakers.

 

FM Band: Both these radios are as sensitive as one another across the FM band; there’s pretty much no difference at all. However I have found that the AR1747 has a better ‘front end’ as it has fewer mixing products than the Degen. For example with the Degen on 102.1 MHz there’s a mixing product from two local radio stations (2 x 103.7 then subtract 105.3 = 102.1). This isn’t present with the AR1747. Selectivity is traditionally one area where portable receivers are not as good as their table top or ‘component system’ type receivers. There just isn’t enough space inside the small cases to fit the necessary circuitry and shielding to achieve optimum results. The AR1747 definitely has better shielding than the Degen, and yet both are equally as selective as one another, there being no discernable difference between the two, at least when used with their internal telescopic antenna. The Degens stereo decoder is by far better, it tends to operate with less ‘hiss’ being introduced, and operates with less disturbance to the audio as it automatically switches in and out. The tonal qualities of the two radios are quite different, the Degen has more emphasis on treble, and on a good clean FM stereo signal does have a ‘brighter’ sound. By comparison the AR1747 has more emphasis on bass – so much so that with a cheap pair of headphones turning up the bass control can overdrive the headphones into clipping and cause severe distortion. A good pair of headphones able to handle this level of bass in the audio reveals no such distortion and shows the depth of bass available on this radio. The AR1747 has an overall more rich, warm & full sound – lacking the sparkling treble response the Degen possesses, but in every other aspect has audio that is more pleasing, both when using headphones and with the internal speaker.

 

AM band: Again the Degen DE1103 and AR1747 are very close in many respects on the AM broadcast band. The Degen has a wide and narrow IF filter for the AM band, as does the AR1747. The Degen’s filters are quite well chosen, the narrow filter being great for separating those radio stations that are right next to one another on the dial, with the wide filter offering better fidelity on strong clean signals. The choice of filter widths on the AR1747 weren’t quite as well thought out, I felt. The AR1747 AM filters are actually rated at 4 & 12 kHz widths, but they sound much wider than those figures suggest. Compare this with the Degen choices of 3 & 6 kHz for their filters. This means that the Degen has a better filter choice for really tough conditions – such as when you might be hunting 10 kHz channels in between the 9 kHz channels where signals are really close by. However, the AR1747 filter set and design has a better ‘ultimate rejection’ characteristic, that is very strong signals well outside the filter passband are better rejected. Where one radio has the advantage, the other makes up for it in another way. Both radios seem to have an equally sensitive receiver, both being able to receive weak mainland radio stations in the daytime, somewhat better than my very sensitive car radio can. Sensitivity of a night time on the AM band isn’t a big concern anyway, which is when most DX’ing takes place. The AR1747 has a pair of high impedance terminals for the AM band, as well as its own traditional built in ferrite rod antenna. This is in contrast to the Degen where the external antenna connection can’t be used on the AM broadcast band. And yet again the superior audio qualities of the AR1747 come to the fore – listening to AM broadcast stations for long periods of time is less fatiguing on the Jaycar product compared to the Degen.

 

Shortwave: Like the AM broadcast band, there wasn’t a lot between the two radios. Both are equally as sensitive all through the shortwave spectrum. Again, the AR1747 was more pleasant to listen to, and despite the lack of a comparatively narrow filter, the tone controls and inherently pleasant audio qualities of the Jaycar product made up for this shortcoming. When used with the internal antennae, both radios seemed to be delightfully free of any intermodulation or cross-mixing products that I could detect. Unfortunately I don’t have an external antenna to test & compare the two receivers in this way. One obvious shortcoming of the AR1747 is the lack of SSB. You can buy an outboard BFO to attach to the 455kHz IF output on the back of the radio from “tquchina” on eBay (look in their eBay shop for a TG37 SSB adaptor, about AUD $50), or if you’re good with electronics build your own small BFO circuit, even install it inside the radio if you want (http://radio.tentec.com/kits/fun/1050)

 

Pros:

Easy to use, nice big display, great sound quality, very sensitive, quite good internal and exterior build quality, very flexible power supply choices and great value for money.

 

Cons:

Not easy to quickly tune in a frequency, filters are too wide for tough signal conditions, and SSB only available with an outboard add-on BFO unit, and the band and bandwidth selector knobs are a bit ‘sloppy’ in their action. The push buttons have a slight ‘lag’ to react.

 

Conclusion:

The AR1747 represents excellent value for money, especially since the Australian Dollar has taken such a big dive recently. The sound quality is superb all things considered. Something I’ve noticed on the internet is that opinions appear to be quite polarised when it comes to receivers in this class. Me? Nah, I try to remain a little more objective than that. But in this case, I do find myself reaching for the little Degen more often. Its not that the AR1747 isn’t as good, I just prefer the Degen.