TS-140S_review_1988.pdf

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1、 JX: ii ii HFBOX If you wanted to get going on HF a few months ago, you had the choice of several rigs. If your eyes gazed longingly at the latest commercial equipments you had little choice Features The set covers all HF amateur bands from 160m to 10m (including the WARC 30, 17 and 12m bands) Kenwo

2、od seem to be reacting to high quipment costs with their new HF rig. But does cost-cutting mean corner-cutting too? Chris Lorek, G4HCL, finds out. below the 1000 mark, and the newly licensed amateur would either have to start saving hard or pay a visit to his friendly local bank manager! It has long

3、 been said that amateur radio is increasingly becoming a cheque book hobby, but lately there has been a trend on VHF towards less expensive rigs, could the same now be happening on HF? The Kenwood TS140S has just been introduced at a selling price of 862, making it cheaper than its predecessors whil

4、e still offering similar features, but does this mean corners have been cut? A glance at the front panel shows a less cluttered array of knobs and switches than usual, but dont let this fool you, the set actually has many more features than it would seem, including a novel built-in morse code indica

5、tor system that tells you whats happening, and an optional computer control interface for the whizz-kids who let their fingers do the talking. on transmit, coupled with general coverage receive operation specified over 500kHz 30MHz, although the actual tuning range is a very wide 50kHz 35MHz. USB, L

6、SB, CW, FM and AM modes of operation are catered for, with each mode change being accompanied by a short morse code identification corresponding to the first letter of mode selected. The transmitter out- put power is specified at 110W PEP for SSB, 100W CW, 50W FM and 40W AM with a slight reduction o

7、n 10m, the set operating from a 13.8V DC supply and drawing 20A maximum on transmit with 1.5A nominal on receive. The TS-680S adds transceive coverage of 50- 54MHz with 10W transmit power. When operating in SSB mode, LSB or USB is automatically selected as you switch from the LF to the HF bands in a

8、ccordance with normal amateur practice, the changeover occurred at 9.5MHz. A VOX facility (Voice-operated Tx switching) is fitted with VOX gain, delay and anti-vox controls on the rear. On the TS-680S a switchable receive preamp operating on 6m and 10m is fitted in place of the VOX. For the CW addic

9、ts, full break- in keying may be selected as well as semi break-in, and an optional narrow CW filter may be fitted and independently selected as required, in place of the 2.2kHz SSB filter normally used, by pressing a front panel button. Separate filters are provided for AM (6kHz bandwidth) and FM (

10、12kHz bandwidth) which are automatically switched in as appropriate for the mode selected. For noise-free monitoring on 10m, a variable squelch is fitted that operates in the FM mode. Two digital VFOs are provided, these tune in 10Hz steps on SSB and CW, and 100Hz steps on AM and FM, the VFOs may be

11、 used independently or for split frequency Tx/Rx operation. Your operating frequency may be varied by using the large VFO tuning knob or by microphone mounted up/down buttons, and an adjacent VFO CH click-step knob provides 10kHz steps for fast frequency shifts or channelised operation. A switchable

12、 RIT (Receiver Incremental Tuning) with a 1.2kHz range is provided to cope with drifting stations after estab- lishment of QSO, an indication of the offset and direction being shown on the sets main display. To suit different uses such as base station, mobile or whatever, the tuning knob stiffness m

13、ay be varied by a friction adjustment around its outer perimeter, and to prevent accidental QSYs a fre- quency bck button is provided on the front panel. Band changes are made by using a pair of large up/down buttons next to the tuning knob, these step either between amateur bands or in 1 MHz steps

14、for general coverage receive as required. 24 please mention HRT when replying to advertisements. HAM RADIO TODAY APRIL 1988 *1 Jlif - Top view of the TS-140. main tuning knob, the memory channel storing the last tuned frequency and mode in each case. As such, they may be used to store amateur or bro

15、adcast band frequency limits together with appropriate modes of operation. Memory channels may be sequentially scanned, the RIT knob allowing you to alter the scanning speed and hence the amount of time spent sampling each channel, any of the channels may be locked out of scan mode if desired. A pro

16、gram- mable band scan is also available, this normally searching between the limits programmed in memory channel 30. If this channel is empty, then the entire range from 50kHz to 35MHz is searched, or if the scan is initiated outside these limits then the channel 30 range is excluded. Again the RIT

17、knob may be used to alter the scan rate. QRM Rejection As the HF bands become more and more crowded, the perfor- mance of a receiver depends not so much as to how sensitive it is, but on how it stands up to rejecting stronger unwanted signals. These may be either from a stronger signal on a closely

18、adjacent frequency where selectivity is important, from a number of stronger signals either within the frequency band or indeed from an adjacent broadcast band all mixing together in the first stages of your receiver, where strong signal handling comes in, or indeed from other man-made interference

19、such as next doors chainsaw or a little further afield from over-the-horizon radar such as the American Pave Paws system. With all this in mind, as well as employing careful circuit design, Kenwood have provided the usual QRM fighting circuits such as a 20dB front-end attenuator and slow/fast switch

20、able AGC (Auto- matic Gain Control) coupled with a manual RF gain slider control, together with an IF shift that moves the crystal filter passband either side of the tuned frequency. A dual- mode noise blanker is also provided, one mode for pulse suppression such as ignition interference, the other

21、for longer pulse widths such as radar, a variable threshold level control gives you a degree of control to prevent the wanted signal deteriorating. As a fighting back measure, a built-in speech pro- cessor may be switched in to give your SSB (or even AM) transmit signal more punch. A variable power

22、output slider control lets you continuously reduce your transmit power down from 100W to around 10W for when things arent tough going or for those who enjoy a challenge. Multiple Memories A total of 30 memory channels are provided in 3 blocks of 10 each, selected by the rotary M.CH/VFO CH knob. Apar

23、t from allowing you to quickly recall Radio Tiranas frequency for easy bed-time listen- ing a couple of useful features are provided. Memory channels 1-10 may store frequency and mode, and memory channels 11 -20 may store split Tx/Rx frequencies as well as the operating mode. A push of the MVFO butt

24、on then allows you to transfer the memory channel infor- mation into the operating VFO(s) as required if you wish to tune around for other activity. Memory channels 21-30 how- ever are designated as Program- mable Band Markers, these store an upper and lower frequency limit as well as a programmed m

25、ode of operation. Once selected, you may QSY or change mode as you wish within the frequency limits you have programmed by a twist of the Dah Dit Dah As well as a short audible CW indication of the mode selected, several other CW messages emanate from the sets speaker, apart from those received off

26、air. For instance, if memory scan is initiated while all memory channels are either vacant or locked out of scan then a Check Memory message in CW is produced, similar indications of Full or Empty are given when checking memories with the 1 MHz step switch selected. Other indica- tions such as Reset

27、 and Unlock are given as alarm indications. All the above may be changed to simple bleep tones in case CW sends you round the twist! Interfaces A large fluorescent display shows the operating frequency to a resolution of 10Hz or 100Hz as desired, together with LED indi- cators displaying the operati

28、onal mode and VFO. A backlit analogue meter shows receive signal strength and selectable indications of the relative output power or ALC level on transmit. Round the back of the set are four accessory sockets providing a multiplicity of functions. The ACC2 connector is designed for RTTY/AMTOR/Packet

29、 controllers, providing receive audio output at a fixed 300mV level, squelch control output, Tx AF input, and Tx key lines 10 HAM RADIO TODAY APRIL 1988 please mention HRT when replying to advertisements. 25 w y IS m; h * aV r Underside of the new Kenwood. (one of which disables the micro- phone). A

30、CC3 provides an inter- connection to the optional AT-250 automatic aerial tuner, and a further Remote socket provides for external linear amplifier Tx/Rx switching, a PIT footswitch, and a speaker audio output. For the computer-control buffs, an optional computer interface may be fitted with the ACC

31、1 socket con- necting to the outside world, but the manual states that youll have to write your own computer program! The set comes supplied with 7 and 13 pin DIN plugs to suit the acces- sory connectors, a heavy duty DC cable fused in each lead with a spare fuse provided, and an instruc- tion manua

32、l giving operating details together with circuit and block diagrams. The set measures 281 mm(W) x 107mm(H) x 305mm(D) and weighs 6.1kg. Technicalities The set is constructed on a metal chassis with a hinge-open arrangement where after removing the covers the set literally opens up like a book, to ex

33、pose all the innards in their glory, this of course makes access for servicing very easy. On receive, the aerial signals pass through the appropriately selected low and high pass filters, broadcast band and IF traps, then into the balanced FET mixer without an RF amplifier being used (although switc

34、hable ones operating on 10m and 6m are fitted to the TS680 model, not tested here). This enables the best possible blocking and intermodulation performance to be obtained without degradation by due to the gain of the RF stage. A first IF of 40.055kHz is used, a monolithic crystal filter being used h

35、ere to obtain roofing selectivity. Individually switched filters are used for SSB, AM and FM, together with the optional CW filter, at the 455kHz IF. A quad-loop synthesiser controlled by a single reference oscillator provides the local oscillator signals common to receive and transmit. On transmit

36、the DSB signal is generated at 455kHz, filtered to obtain the required sideband, amplified and mixed to 40.055MHz, filtered and mixed again with the VCO signal to achieve the final RF frequency. On FM, the first mixer oscillator is directly modulated. A pair of 2SC2879 PA transistors provide the 100

37、W output level from the set. On The Air After coupling the set up to my 25A DC power supply unit and HF aerial system, I busied myself tuning around the bands to get a general feel of the set, and I must say I was pleasantly surprised to find the set was quite versatile despite its simple control ap

38、pearance. I found the program- mable band memories very useful, in fact after programming my favourite amateur band segments and modes, together with a couple of broadcast bands, I used these memories in preference to the band change switch for normal use. This way switching from one amateur band to

39、 another always placed me in the portion I required, ratherthan the set just changing the MHz digit as appropriate and requiring yours truly to perform a QSY job each time. I had several pleasant QSOs on the amateur bands, both on SSB and using AMTOR and Packet modes with the set coupled up to my KA

40、M unit. As a microphone is not supplied with the set, a quick wiring job was performed to couple my usual desk and fist mics up. In asking for audio reports, little difference was noted between the TS-140S and my usual top per- formance equipment, although reports received when using the speech proc

41、essor were a little in- different from stations who were receiving me at a reasonable strength. Testing the set on AMTOR, at least with the European and American stations heard over the review period, showed it to be adequately fast in its Tx/Rx change- over without further modifications being requi

42、red. I appreciated the accessory Tx keying line that muted the microphone on transmit, using this for data communications means that you dont need to remember to unplug the mic each time for fear of corruption. This was a limitation with the TS-440S (reviewed HRT Aug 86) so maybe someone out there i

43、n the land of the rising sun did their homework! Around The Bands Around the amateur bands I 26 please mention HRT when replying to advertisements. HAM RADIO TODAY APRIL 1988 FILTER UNIT SIGNAL UNIT n Vt nrJ -o -w- -fe* CD D TTV -h-Q-O- b-Q-M- MZH e: -to- -;V!-:-i r=;y y-y SIU -S LL _j L_ r n J L TS

44、-140 circuit diagram. found the receiver to be very quiet, not through lack of sensitivity but due to the absence of all the burbly rumbles one often hears on the LF bands, such as 40m, at night on less-than-perfect receivers caused by internal mixing products. I found that by switching the attenuat

45、or in provided no discernible improve- ment apart from giving my ears the occasional rest, showing the front end was not being driven into non- linearity through overloading. On my 160m/80m/40m trap dipole at least (over 200ft long in all) I en- countered no blocking problems from the many high-powe

46、red broadcast stations to be found on the bands. I did however note a glitch in tuning through 50kHz steps inthefrequency ranges, inthe presence of strong AM broad- casters this would often bring about a sudden decrease in sensitivity as the S-meter deflected almost fully for an instant whilst tunin

47、g. This is due to the now common multi-loop synthesiser approach being employed in many sets, the glitch occurring as one sub-loop takes over from the other, but neverthe- less I still found it annoying. Laboratory Tests The receiver sensitivity results on SSB did rather surprise me as 1 would have

48、expected a slightly deafer set due to the absence of an RF amplifier stage. The AM sen- sitivity was a little poorer but still acceptable in view of the power rat- race that occurs on the HF broad- cast bands. Of note though was the extremely good strong signal performance measured, so good in fact

49、that I believe the set is in a class of its own at this price level. I tried very hard to find traces of reciprocal mixing from the syn- thesiser when measuring the selec- tivity of the set with my low-noise cavity tuned signal generators, and although I did find a slight increase in noise centred around 6kHz HF of the wanted signal frequency, I had to increase the unwanted signal fed through a hybrid combiner by over 80dB over the S3 level to show up on an adjacent S3 strength received SSB signal. To put this in real