IC-703_review_PW_2003.pdf

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1、GIDEAL FOR PORTABLE FUN & A PICNIC Neill Taylor G4HLX, the PW 144MHz QRP Contest organiser enjoys outdoor Amateur Radio. This time hes been sampling the latest offering from Icom during a picnic and portable excursion! 38Practical Wireless, October 2003 T he latest addition to the growing range of s

2、mall h.f. transceivers is the little IC-703 from Icom. The transceiver is little in the sense that its lightweight, low power and physically quite small, as well as being comparatively low cost. However, as I found out on the air, the IC-703 is certainly not a little rig when it comes to features, a

3、nd holds up pretty well against the big boys in transmit and receive performance! The IC-703 easily-portable transceiver is bound to look attractive to those who like to take their Amateur Radio beyond the shack and the car. In particular I think it will appeal to back- packers, climbing to hilltops

4、 or other exotic locations on foot. It will also find a home in the shack of a QRP enthusiast, working fine as a base station, and in particular I think it will appeal to holders of a Foundation Licence. Whats In The Box? Right.now Ill answer the question.”Whats in the box for you”?. On arrival youl

5、l find that the IC-703, heading photograph, provides (in a box measuring about 220 x 170 x 60mm and weighing under 2kg) coverage of all h.f. bands plus 50MHz. The transceiver has 10W transmit power output on s.s.b., c.w., f.m. or data modes, and 4W on a.m. It also includes a general coverage receive

6、r with a tuning range from 30kHz to 60MHz. Additionally, the transceiver has a built-in auto antenna tuning unit (a.a.t.u.) and digital signal processing (d.s.p.) as standard. In short, add an antenna and a power supply or battery, and you have a complete and highly portable station. The optional ca

7、rry bag makes this even easier. In appearance, the IC-703 looks very like the older and well- established IC-706 series. In fact, the front panel is entirely identical with the IC-706 MkIIG (apart from the name IC-703!). The functionality of these two transceivers is very similar, too, with the IC-7

8、03 menu system, etc., very much like that of its older cousin. However, theres no doubt that the IC-703 has been designed with portable operation in mind! For example, the designers have worked hard keeping current consumption low to preserve battery life. Basing its functionality on the IC-706 seem

9、s like a good idea, given how popular the 706 continues to be, some eight years after the first model was launched. As an all-in-one low power rig HF/50MHz Transceiver Icom IC-70 G The Icom IC-703 is - as indicated by the normal sized fountain pen - a small rig. But, as Neill Taylor G4HLX explains.i

10、t offers much more that youd think and includes some surprising extras! G An inside view of the IC-703 transciever. 38,39,42,43 IC-703 22/8/03 10:40 am Page 38 Practical Wireless, October 2003 39 for the QRP enthusiast or Foundation Licensee, the IC-703 seems to provide everything you need. Except t

11、hat is.for coverage of the 144 and 432MHz bands. This is an unfortunate omission, in my opinion, although Im glad they managed to squeeze 50MHz into the box though. Neill Impressed! I was keen to try out this little transceiver on the air, and when I powered it up for the first time I was at once im

12、pressed.it didnt have a small rig feel or sound. Tuning in some s.s.b. stations on 14MHz, I found the audio through the internal speaker to be full and clear. The large tuning knob is comfortable, although there are two settings of dial tension, and I would have preferred the lighter one to be slack

13、er for more of a spin. The menu system is easy to access, and I could guess what many of the items did before delving into the manual. The receiver does seem to have good sensitivity. On 50MHz I used it to listen to a beacon which is marginal at my QTH. Comparing the IC-703 with my other 6m band rec

14、eivers I found it to have quite acceptable performance, and I would have been happy to use it for DX work on this band. I was then ready to do some transmitting, so I thought it was time to open the manual and have a read. The description of getting started all seemed a bit long-winded, but would pr

15、obably be quite helpful for an absolute newcomer. Anyway, I soon found how to adjust the microphone gain and audio compression level for my voice (the initial settings were, in fact, just right). I also learnt how to use the automatic a.t.u. (a.a.t.u.), which was simple: just press the button! I was

16、 soon enjoying a string of QSOs on 14MHz s.s.b. I was reminded, once again, that plenty can be achieved with just 10W output power, provided youre not too ambitious. The quality of the transmitted audio sounded good to me (I recorded this on a separate receiver). I also received several complementar

17、y reports of the audio quality from the stations I worked. The speech compressor provided a worthwhile increase in signal punch without degrading the quality of the sound. Using CW Next, turning to c.w., where the full potential of QRP is to be realised, I found the rig to be quite capable. One of t

18、he optional c.w. filters would be necessary for serious c.w. operating, though, the options being 500 or 250Hz. The built-in iambic keyer is very easy to use, I just plugged in my paddle and away I went. Various menu settings allow the keyer to be configured for personal preference. Its even possibl

19、e to set it to use the Up and Down buttons on the microphone in place of a paddle key! To my surprise I found this moderately easy to use, and it would be useful in an emergency, maybe, if operating portable without a key when the need to switch from s.s.b. to c.w. arose. Either full or semi break-i

20、n, with adjustable delay, is available. The full break-in works well, and I could hear between the dots when sending at speeds up to about 20w.p.m. However, I was surprised to find that relays are used for the transmit- receive switching. And although theyre not loud, I found the constant clattering

21、 quite distracting (I suppose I wouldnt have noticed it had I been using headphones). But the semi break-in, with a short delay time, suited my operating style nicely. The c.w. keyer also features three message memories. These are not loaded with a message using your key, but by a fairly complex ope

22、ration using the menus. Having programmed-in your three messages, its then easy to send them with a single button press. One of the three messages can be used to send a report and contest serial number, which automatically increments each time its sent. This is all very clever, but I think it would

23、only be useful for rather casual contest operating. For serious contesting, automation of serial numbers, etc., is bound to be done by your logging software running on a PC. Interfacing this sort of thing with the IC-703 is enabled by its Icom standard CI-V computer interface (an optional level conv

24、erter is needed to connect it to a RS-232 port on the computer). The FM Mode The f.m. mode, while not essential for h.f. operation, is properly supported by this transceiver. It has a CTCSS tone encoder and decoder, as used to access many v.h.f. repeaters. The transmit frequency offset for a repeate

25、r has to be set up using the split function, and then the combination can be stored in a memory, complete with the tone frequency. It seemed a bit odd to find all this in a transceiver without 144 or 433MHz capability. Tuning & Controls The main tuning dial is smooth, and in s.s.b. and c.w., a 10Hz

26、tuning step 703 G Rear panel view onf the IC-703 (see text). G The detachable main front panel (see text). 38,39,42,43 IC-703 22/8/03 10:40 am Page 39 GIDEAL FOR PORTABLE FUN & A PICNIC 42Practical Wireless, October 2003 is standard, although a very fine 1Hz step can be set with a single button pres

27、s. Faster rates can be set according to your preference, and a menu option gives you a quarter-speed slow tuning rate. A nice feature (which I didnt see mentioned in the manual).is that if you spin the dial fast enough it switches to a quicker tuning rate to rapidly QSY. Band Up/Down buttons move se

28、quentially through all the Amateur bands from 1.8 to 50MHz. The buttons also select the general coverage receiver, which appears in the sequence at the appropriate position, depending on the frequency that you last left it. For example, I tuned it to one of the experimental 5MHz frequencies and when

29、 switching up through the bands 60m appeared between 3.5 and 7MHz (but of course the rig cannot transmit on 5MHz). There are two v.f.o.s on the IC-703 with the usual ability to operate split (transmitting on one and receiving on the other). Although setting up the split frequencies is easy on the IC

30、-703, I particularly liked the quick- split function. Having previously defined a split offset via a menu setting (I chose 5kHz), the split can be set up practically instantly by pressing the SPL key, assuming you have the right menu showing at the time. So, if you are waiting to get through a pile-

31、 up when the DX station suddenly says “Im going split - listening 5 up”.you can be first in the queue on his new receive frequency. (You and all the other IC-703 owners, of course!) Memory Channels The IC-703 has 99 memory channels, and I found them very easy to set and to use. Frequency and mode ar

32、e stored, and if split operation is selected, the independent transmit and receive frequencies are stored. There are three further pairs of memories that can be used to store scan edges. As well as v.f.o. scanning, a scan the through memory channels is easy to run, with individual channels skipped f

33、rom the scan if desired. All the usual scan options are available, utilising the all-mode squelch to search for a busy channel, for example. In addition to the 99 memories, theres also memo pad, in which a single button press stores the current frequency and mode in a rotating bank of five memories

34、(it can be increased to ten via a menu setting). This is very handy when tuning the band in the search and pounce mode, when you hear a station who you want to work, but who is busy or has too many callers. All you do is pop the frequency in the memo pad and come back to it later. Portable Power As

35、I mentioned before, the IC- 703 is predominantly a portable rig and can operate on a supply voltage between 9 and 15V. Because of this flexibility a variety of battery supplies would be suitable. Icom offer a 9.6V 2.8AH NiCad pack as an option, and I found this to be effective. I didnt operate long

36、enough to flatten this battery between charges, but I would expect a few hours operation to be possible at normal transmit/receive time ratios. When the rig detects that its supply voltage is 9.6V, or anything below about 11V in fact, a range of power-saving features switch in automatically. The max

37、imum output power drops to 5W and the backlight of the main l.c.d. display switches off when no control has been touched for a few seconds. Other power saving features can be selected by the menus, including a Power Saver when youre receiving with the squelch enabled (its similar to this kind of fun

38、ction found in v.h.f. hand- helds). When operating from a 9.6V supply, I measured the current consumption to be about 300mA when receiving a signal at a comfortable audio level, and 1.7A for 5W continuous power output (rather less on average in s.s.b. use, of course). In fact, the figures Ive quoted

39、 are quite low compared with many amp-guzzling radios. This suggests that considerable design effort has gone into optimising the IC-703 for battery use. Unexpected Extras Now on to some of the extras that are featured in this transceiver which you might not expect in a basic modestly-priced rig. An

40、d Ill start with the i.f. shift control. The control enables the i.f. pass band to be moved up and down in frequency when s.s.b. or c.w. modes are used. This can be useful to avoid problems from strong signals on adjacent frequencies. In c.w. use, since I didnt have one of the optional narrow filter

41、s, I found this shift control very useful to eliminate other c.w. signals nearby the one I was listening to. The other extra - the DSP - provides just two functions: On s.s.b. an automatic notch filter can easily be enabled that searches for constant tones and notches them out. Thus heterodynes from

42、 extraneous sources can be eliminated, and I found that it works well. When youre using s.s.b. or c.w., the DSP noise reduction can be switched in. This removes much of the noise content of the audio signal, and certainly provides a marked change to the quality of the sound. In use.with many s.s.b.

43、signals of modest strength (when theres a significant background noise level) I found the facility definitely makes the speech sound as though it has better fidelity. But whether or not it made it more intelligible.Im not sure. I found many signals that the noise reduction made nicer to listen to, b

44、ut despite trying hard.I couldnt find any signal that became readable with the noise reduction, but unreadable without it. Another extra.the a.a.t.u. is a very useful device to have built in to the rig, especially for portable use when its necessary to sling up a temporary antenna. But remember.its

45、not designed to match a very wide range of impedances, so you cant just plug in a random length wire and expect to get a match on all bands. However, although Icom offer an optional external a.a.t.u. with a wide range capability, the internal one is specified as being able to match loads up to a v.s

46、.w.r. of 3:1 (a little less on 50MHz). And to see what this means in practice, I first put up a dipole cut for 14MHz. The a.a.t.u. easily matched the antenna not only on 14MHz, but also on 7, 18 and 21MHz too! Of course, just because a match is achieved doesnt mean that power is effectively coupled

47、to the antenna, nor that the antenna is efficient. But its a start. Next I tried the a.a.t.u. on my dipole cut for 7MHz. To my surprise it could match this on all nine bands 1.8 to 28MHz. G The main battery pack (see text) and power supply.clearly proving how small the IC-703 is! The inset photograp

48、h shows the adpator units for use internationally. 38,39,42,43 IC-703 22/8/03 10:40 am Page 42 Icom IC-703 Icom (UK) Ltd. (01227) 741741 Pros: .”when I powered it up for the first time I was at once impressed.it didnt have a small rig feel or sound.”as a complete all-in-one portable h.f./50MHz rig,

49、the IC-703 has a lot to recommend it.I have to admit to being most surprised at how much I admired one of the optional accessories for the IC-703.the carrying bag! Its an extremely well thought-out backpack- style bag Cons .”the manual contains a number of errors.”. “The omission of v.h.f./u.h.f. capability, while understandable in a rig of this size, is the only aspect that may lead a new Foundation Licence holder to consider the alternatives”. IC-703 703.53 LC156 Carry case 62.06 BP228 Battery pack 71.76 Charger for Battery pack 67