ilt,every undergoes24-hour burn-in, then is aligned and tested tomeet or exceed every spec on the data sheet.Which makes us very confidentabout warrant­ing your KWM-380 for one full year.

The result is a radio with superior perform­ance and lasting quality, not front-panel glitter.

Frequency stabil ity is just one example 01 itsbeauty: typically, drift is as low as 10-12 Hz perhour for normal ham shack environments.Other companies haven't matched our perform­ance because they don't match our qualitybehind the panel.

Add some real beauty to your station.See the KWM-380 at your nearest authorized

dealer. Collins Telecommunications ProductsDivision, Defense Electronics Operations,

Rockwell International, Cedar Rapids, IA52498. Phone (319) 395-5963. Telex: 464-435.

, , Rockwell International

At Collins, we know e isettle for less than professional performance.So we build every KWM-380 to commercialrather than amateur standards. For example,our PC boards are connected by ribbon cableswith gold-plated pinlield connectors, The boardsthemselves are all glass epoxy, and virtually

unaffected by temperature and humidity whichcause intermittents in the more commonlyused phenolic boards.

...where science gets down to businessCIRCLE 50 ON READER SERVICE CARD

Table 1- Manufacturer 's specifications.

" 1.7 kHz"360 Hz"140 Hz

Parameter

PhysicalSize

Weight

EnvironmentalOperating temperatureOperating humidityOperatmq alt itudeVibration

EltctricllPrimary cower

RtctiverFrequencyModesSensitivity (Using "sen ltVmeasurement)seecnvev (3 dBbandwidth)

1.1. and image rejectionmterrrecutauon dlslorll()fl

AGe

Audio output

TransmitterFrequency

ModesOutput power

Unwanted signal suppressionCarrierUndesirecl sideband.1 kHz retHarmonics (all)Mixer productsThird order distortion

Synthesizer accuracyand stability

Antenna impedlnce

AudiO inputsMicrophone

line

Say You Saw It In CO

Specifications

394 mm (15.5 in] wide; 190 mm (7.5 in.) high, including25 mm (1 In.) feet; 457 mm (18.0 in.) deep27.2 kg (50 lb.), max

o to 50°C (32 to 122°F)o to 90 % relative humidityo to 3049 m(0 to 10,000 fl. )2 g's, 101033 Hz

Strapoable for: 105, 115. 125121 0. 220, 230, 240. 250 V± 5%, 50 to 60 Hz; or 12 to 15 V oc. negat ive ground'120 watts max in receive. 600 watts max in transmit

0.5 fO 30.0 MHz, tunable in 10 Hz stepsu s.o.. r.s.c.. a.rn.. and c.w.0,5 "V or better lor 10 dB (s + n)ln, 20 to 30.0 MHz,s.s.o. and c.w.; 1.0 "V or better for 1.8 to 2.0 MHz,Selectable:

8 kHz"6 kHz2.1 kHz

"Optional FiltersGreater Ihan 60 dB- 50 dB or better lor two signals of - 10 dB mW each.20 kHz apartAudiO output variation not more than 8 dB lor 4 "V to200 mV open circuit d . input variationNot less than 3 W into 4 ohm load. at 1 kHz. at not morethan 10% tota l harmonic distortionline eucre output not less than - 10 dB mW nominal m­to 600 ohmsFrequency response: 300 to 2400 Hz with not more than5 dB variation

160 through 10 m amateur bands. tunable in 10 Hz steps160 m 1.800 to 2,000 MHz80175 m 3.500 to 4.000 MHz40 m 7.000 to 7.300 MHz20 m 14.000 to 14,350 MHz15 m 21.000 to 21.450 MHz10 m 28.000 to 29.700 MHz

u.s.b.. I.s.b.. and c.w (ATTY by AFSK on Ls.b.)90 W pep, min (too W, nominal)In cw or ATTY: 50% duty cycle; key down 15 minutes.max, Automatic turndown to 50 W aller 10 seconds.With optional blower kit installed. power is 100 Waverage. 50% duty cycle, key down 1 hour max at 25°C;30 minutes max at 50° C for all modes,

- SO dB or better

- 55 dB Of better- 40 dB or better- 50 dB or better25 dB below each tone of 2-tone test

Accuracy WIthin :!: 5 Hz after 10 minutes warmup when39.6 MHz and 455 kHz oscillators are set to Within± 3 Hz.Stability within :!: 150 Hz over temperature range of 0 10so oC (32 to 122°F) if osci llator's set within 10 Hz at25°C (77°F)

50 Ohms. ncoreecuve. (Full transmitter power outputWith v.s.w.r. 012:1 or less. Automatic power output turn­down with v.S.w.r. greater than 2:1.)

low or high impedance. dynamic; 3.3 kG nominal impe­dance600 Ohm, unbalanced: 40 mV inpul sufficient lor lull r.t .power output

various specific functions. An examine­tion o f slightly more deta iled receive andtransmit signa l path block diagramsshould he lp to c larify the situation .

For instance , f ig . 2 shows deta ils of thereceive signa l pa th. The "front-end" ofthe KWM-380 is unique in several reospects. There is no r.I. ampuner stage,and there are none of the usual bandpassf ilters as are usually associated even withtransceivers having a " h igh" first i.t.(above 30 MHZ). The t ilter b locks that anincoming signa l goes through before be­ing amplified are not quite w hat onewould expect . The first filter block is a0.5- 1.6 MHz rolloff one, simply designedto protect the transceiver from BC bandove rload. The t nqn-passurter block worksin conj unction with a fo llowing 30 MHzrow-pass f ilter b lock. The latter is f ixed infrequency at 30 MHz, while there is a se­lec tion of three h igh-paSS fi lter cutoffs ofabout 20, 14, or 7 MHz. So. an incomingsignal can be "bracketed" between 7-30MHz, 14-30 MHz, or 20-30 MHz.

The reason for this arrangement is notSimp ly to provide image signa l rejection;the very high f irst U . frequency takescare o f that. The h igh-pass fi lters ensurethat the transceiver does not generatesecond order intermodu lation productsof com me rcialfbroadcasti ng stations.For instance, in the European area the" breakth rough" of 13-15 M Hz signa ls on" s imp le " transceivers operating on 10meters can be a very severe problem.The problem doesn't ex ist with theKWM·380. In between the high- and low­pass filter blocks one can see a PIN diodeattenuator (CR104). This d iode is con­trolled by a voltage from a.a.c. amplifiersin the KW M-380. Essentia lly. the diodeperforms the same func t ion in an auto­matic fashion as the manual r.f. attenua­tor switches one f inds on many h.f . trans­ceivers.

The 39.1 45 MHz i.f . signal is producedby the fi rst "U100" mixer. This U. signalis amplified , passes through an optionalnoise blanker unit. and then goes on tomixer " U 102," where the i.I. signal istranslated to 455 kH z and routed to apassband tuning assembly. An up/downfrequency translation takes p lace in thisassembly in that the 455 kHz i.t. is trans­lated toan i.I. of 6.255 MHz and then backdown aga in to 455 kHz. True signal setec­t ivity takes place in crystal filters associ·ated with the 6.255 MHz U . The final 455kHz U. signal is demodulated to providean audio output and rectified to providethe cont ro l voltage for an elaborate" hang" a .g.c . loop w hich controls boththe incoming signal attenuation (PIN or.Odes between the h igh-pass and low­pa ss f ilter b locks) and the f inal 455 kHz i.f.signal attenuation (PIN dicx:les before the" U700" stage shown in fig. 2). The 800 HzSpot Tone input shown in the lower lett­hand corner of fig . 2 provides for a con­venience teature. in that in the cw. modeonly. one can enable an 800 Hz lest lone

November1982 • CO • 51

•

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Fig. 1- Overall block diagram of the KWM-380.

to which a received c.w. tone (centeredon 800 Hz by a c.w. i.f. filter) can bematched for exact transmit/receive fre­quency coincidence.

II would be fun to highlight in detail nu­merous unique circuits used in the KWM­380. However, if one has to use a practi­cal approach by both serving potentialpurchasers of the KWM-380 and givingreaders some circuit ideas, the foHowingshould be of special interest.

The basic " front-end" of the KWM-380is shown in fig. 3. This diagram shows indetail and w ith circu it va lues the variousfilter sec tions previously mentioned. Theantenna signal f irst encounters the multi ­p le-pole Be band rouot t fi lter shown asL8lJO.804 and C80().801 . The three high·pass fillers are each composed of a simi­lar number of components (e.g., f ive ca­pacitors and two inductors). The 100 phcoils on each side of each filter are RFC'swhich are used for signal isolation in thePIN diode switching scheme used.

If one studies the diagram a bit , itshould be c lear that when point K(7) isgrounded, the fillers are bypassed by di­odes CR800·801 . When one of the pointsL(7), M(7), or N(7) is grounded, one of thethree filters is selected. The incoming sig·nal then passes on to the diode sectionbetween C825-Cl02. This diode sectionis an overload protector composed ofzener diodes VR100-101 and limit at the 7vonrevet. C104 is switched to ground by

the variable resistance of PIN diodeCR104, which in turn is driven by thechain of a.g.c . amplifiers shown at thebottom of this diagram. The incoming sig­nal then goes through the fixed 30 MHzlow-pass filter and on to mixer U 100.U100 is a commercial diode ring mixer(type SRA1H from Mini-Circuits Lab.,Brooklyn, NY. 11229). The signal is, ofcourse, then translated to the first i.L. butnote that only then does signal amplifica­tion take place . The whole "front-end,"so far, has been passive.

The concept and practical usage of thepassband tuning used in the KWM-380 isillustrated in fig . 4. The 455 kHz signalcoming into mixer U4 has a bandwidth upto 8 kHz. Aller m ixing , the resultant 6.255MHz signa l is routed to anyone of f ivecrystal filters: a standard s.s.b. fi lter (2.1kHZ), standard a.m. filter (8.0 kHz), an op­tional narrow filler for s.s.b. (1.7 kHz) , oroptional narow filters for cw. (140 or 360kHz). One also has the option of physical­ly substituting an optional 6.0 kHz filterfor a.m. for the standard 8.0 kHz one.These filters are all switched in and out bysome orode.transistor switching circuitryas cont rolled by the front-panel selectivi­ty control. The 6.255 M Hz signal is thenretranslated to 455 kHz in mixer 01.Since mixers U4 and 01 have a commoninjection oscillator, varying the trequen­cy of that oscillator moves the selectedfilter bandwidth chosen within the overall

The back panel of the KWM·380 consistsalmost entirely of a huge heat sink. Noblower fan is necessary for normal s.s.b./c.w. operation. Various jacks for acces­sory connections are shown on the ocr­tom of the panel. The r. f. output coooec­tor (left. bottom) is really an S0-239. Au.h.f.lBNC adapter was left in place by

mistake while taking the picture.

incoming 8 kHz bandwidth of the incom­ing 455 kHz signal. The effect of all this isshown in fig. 4(8). It shows the passbandtuning effect as one varies the passbandtuning control when a standard s.s.b. fil·ter has been selected. Two things shouldbe noted: the filter bandwidth does notvary as its placement is varied, and theoperator must set the passband tuningcontrol so either l.s.b. or u.s.b. signals arepassed.

Referring back to fig. 1, one can notethat the microprocessor control block

52 • CO • November 1982 Say YOUS8W It InCa

.... 11"·01 .

70B GAINHIGHEST GAIN2 MffiR OMNIOlITP£RFOOMSCONE ANDOOUBlE ZEPI'VvOOK MORE STATIONSBJMINATE NOISElIGHTNING PROTECTEDACCESS MORE REPEATERSASSEMBlE EASILYINSTAlLQUICKLYA COMftETE ANTENNAALL PARTSINCLUDED600,000 HAPPY' USERSBECOMEONE TOCiWAAX-2B134 -164MHzARX-220B220-225MHzAAX-45OB 435-450MHz

RINGORANGERII

MORE RANGE3 dB GAIN5/8 ASTAINlfSS INHIPGRIPTIGHT!lll.BMAGNETCHROMEPLATED BASeNEAT APPEARANCETHUMB lOCK ADJUSTMENTNO YJHIP CUTTINGLlJN PfUCEMAGNETIC MOONTSAMS-147 146-148 MHzAMS-22O 220-225 MHzTRUNK UP MOUNTS,4JS-147 146-148 MHz,4JS-22O 220-225 MHz

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, "

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range of the transceive r. However, whenpower is turned off and then turned onagain, the v.t.o.:s are always reset to 15MHz . The frequency generation and con­trol is arranged such that frequency cov­erage is continuous without any break for"bands." That is, if the fastest tuning rateis chosen . three revolutions of the tuningknob will completely set the transceiveron any desired frequency between3.000.00 and 29.999.99 MHz (receivemode; transmit mode is limited to ama­teur band segments). The other select­able tun ing rates are 200 kHz. 20 kHz,and 2 kHz for one main tun ing knob revo­lution.

Fig. 5 shows a lew details of the trans­mit chain in the KWM-380. The basicmodes generated are s.s.b. and c.w. Fors.s.b. generation a d.s.b. signal is gener­ated at 455 kHz in balanced modulatorU50 ' . The signal is then routed throughthe 2.1 kHz filter contained in the pass­band tuning circuit used on receive andtranslated again to 455 kHz as an s.s.b.signal. On transmit, a front-panel modeswitch automatically sets the variable os­cillator in the passband tun ing ci rcuit so aselected I.s.b. or u.s.b . signal is generat­ed. In this manner, and considering theaction of the passband tun ing control on

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commands a cent ral position as regardsaccepting input commands from the fre­quency luning cont rols and then sendingout data to various blocks such as thosefor the synthesizer . frequency display,and high-pass and low-pass filters. TheCPU itself is a type 6802. There would beno point in going into all the complex cir­cuitry within the microprocessor and itsassociated blocks. For example. thereare several complex PLL loops with in thesynthesizer. But. the genera l concept ofcontrol exercised by the microprocessoris interesting. It accepts tun ing informa­tion from the main tuning knob via photo­choppers and senses if the tuning knobrotation is up or down. It also accepts tun­ing rate control information from switchsett ings. It then supplies this data to thesynthesizer for frequency generation in'0 Hz steps and to the frequency displayfor readout to ' 0 Hz steps. When certainfrequency limits are reached, it sendscontrols to d iode switch in or out high­pass filters in the receive signal chainand relay switch low-pass fillers in thetransmit signal chain.

Frequency set information is stored forthe two AlB v.f.o.'s in the KWM-380 dur­ing operation, and the two f requenc iescan be anywhere within the operating

Fig. 2- Block details of the receive chain in the KWM-38D.

.'Of''''

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----. ... 'c .. ,· .. CO '

•

Say You Saw liin COCIRCLE 70 ON READ£R SERVICE CARD

53

Looking inside the bottom of the KWM-380 with its cover re­moved, one sees basically one huge, double-sided PC boardwhich contains the basic receive/transmit circuitry (excludingfilters, oscillators, frequency readout circuitry, etc.). Note the

extensive use of ribbon-type cable with connectors.

Removing the overett shell cover on the KWM-380 plus an inter­nal shield cover, this is what one will see. The individuallyshielded compartments on the right contain various PCboards,while the internal power supplycomponents (transformer, filter

capacitor, etc.) are seen to the left.

receive, one has independent control ofsideband selection lor transmttrreceive.The 455 kHz s.s.b. signal is further Ire­quency translated up to the final operat­ing frequency by the same rnixerroscltla­tor circuits active in the receive mode.The signal reaches the 100 mW level inbroadband amplifier stage 0202-204 andis fed on to a power amplifier block.

For c.w. operation, the 455 kHz carriersignal normally injected into the batanc­ed modulator is diode switched into the455 kHz i.t. chain preceding the pass­band tuning block. This 455 kHz carriersignal is also gated for c .w. keying by a di­ode switch. 0503, which is controlled bya pulse shaping circuit, U5OOC, whichprovides for controlled rise and decaytimes during c .w. keying. The c .w. keyingc ircuitry also activates a sidetone osciua­tor feeding the microphone preamplifierstage. This is provided so the VOX circuit­ry can also be used on c.w. for receive/transmit switching. The sidetone outputis not used togenerate a c.w. carrier. TheVOX circuitry provides for separate "de­lay" control settings in the C.w. and s.s.b .modes.

On both s.s.b. and c.w. the output levelessentially can be adjusted for ORP lev­els to full output . On s.s.b. this is accom­plished by control of the microphone am­plifier gain and on c .w. by circuitry whichdirectly controls the r.f. carrier level viacontrolled biasing of the a.l.c. loop.

Metering provides for monitoring thea.l .c. level, using the same scale as for S

54 • CO • November 1982

readings on receive, and for direct read­ing of forward and reflected power levelsas sampled at the output of the power am­plifier.

Physical ConstructionAs was mentioned before, the KWM­

380 is not a "light-weight" unit. But, theweight, besides deriVing from a bultt-lnpower supply, comes about from abso­lutely solid construction. This is initiallyapparent trom the tront-panet controlsand switches which are all weu-dimen­stoned and 01 excellent quality. Taking alook at the back 01 the KWM-380 (seephoto), one sees a massive cast alumi­num heat sink which covers most of therear 01 the unit. It wasn't measured, but Iwould easily estimate that it containsmore square inches 01 cooling area thanare contained on the heatsinks of some 1kw conduction-cooled linear amplifiers.The back panel view also shows the nicelayout 01 the connectors used, rangingfrom the antenna and a.c. power connec­tors on the left to the various connectorsfor linear amplifier controt. speaker, key,etc. , on the right side. The special con­nector in the center is lor a special key­board control option (described later).

To get at the inside of the KWM-380,one has to unscrew and slip off a com­plete wrap-around. perforated steel shellas can be seen in the rear view photo.looking inside from a top view, one seesthe power supply components on the left

side and a multi-shielded compartmenton the right side containing various PCboards. Very extensive use is made of rib­bon cable interconnecting runs, whichare long enough so any individual PCboard can be removed for test/replace­ment without using extender cards. AI·though it is not too easy to point out, thesingle internal crystal oscillator whichlocks the frequency synthesizer is in itsown separately shielded compartmenton one of the front PC boards. The poweramplifier is in a separately shielded com­partment at the rear of the unit.

Taking a look at the exposed undersideof the transceiver (see photo), one againsees the very extensive use of intercon­necting cables between PC boards. ThePC boards in themselves are quite inter­esting to study. They are of a high-qualityglass epoxy type with fully plated-throughholes, where applicable . Someone atRockwell/Collins must have given "or­ders" that no component may be diaqon­ally mounted on a PC board, and evendisc ceramic capacitors have to be abso­lutely lined up at "attention" rather thanbeing allowed to find their often rathernatural, netter-sketter mounting state.

Seriously, however, the physical con­struction of the KWM-380 has to be ratedas excellent. Any constructional featurethat one looks at augurs for a very longservice life for the unit along with reason­ably easy service possibilities should acomponent or board require replace­ment. Not to detract from the foregoing

Say You Saw It In CO

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erating placements subject to conditionssuch as a heavy sart-water-Iaden atmos­phere give rise to possible problems. Theother point-an extremely minor one tobe sure-concerns the microphone in­put jack. It requires a special PJO-68 plug

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111, I,.

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but yet to give the reader a complete pic­ture of the KWM-380, one should mentiontwo things. If one is going to use theKWM·380 under extreme environmenta lconditions, one has to take note of theperforated covering used. Obviously, op-

Brings ,ou theBreakthroughl

Prices and Specifications subject tochange without not ice or obli gation.

Software copyright by AEA.

AEA once again breaks newground in the code com­munication s field with thenew model MBA-RC reader/­code converter. The MBA·RCdecodes Morse, Baudot orASCII signals off the air anddisplays them on a large 32character alphanumeri cvacuum fluorscent display. Inaddition, it will output Morsecode for keying your transmit­ter. It will also generate RTTY(Baudot or ASCII AFSK twotone output. (170 or 850 Hzshifts.) Any of the acceptableinput codes can be convertedto any of the specified outputcodes (any speed to anyspeed). If yo u have any of thecommo n Baudot ATTY ter­minal s as an example, youcan now send and receiveMorse and ASCII with yourkeyboard and printer. You caneven generate ASCII o rBAUDOT Rny using yourMorse hand key or memorykeyer.

Get the details. Write for ourfree product catalogue or bet·ter yet , see your favo ritedealer.

ADVANCED ELECTRONICAPPLICATIO NS, INC.P.O. Box C·2160,Lynnwood, WA 98036(206) 775-7373Telex: 152571 AEA INTL

FLEXI­BILITY

56 CIRClE nON REAOER SERVICE CARO Say You SIlw It InCa

tton that the KWM-380 will deliver a good100 watts output over all of the amateur

Fig. 4- (A) Basic passband tuning scheme used in the KWM-380. (B) An illustration ofhow an incoming signal is affected.

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bands. It probably could be adjusted toprovide 1Y2 times that power level andfor normal s.s.o. operation would run justas cool. There is no fan included in thestandard KWM-380, nor is one neededfor norma! c.w. or s.s.b. operation thanksto the huge PA neatstnk on the rear of theunit. For AFSK RTTY operation over ex­tended periods, there is an optional blow­er kit available whic h allows 100 wattsaverage output w ith a 50% duty cycle tobe maintained for one hour under keyedconditions! The power amplifier stagecontains all sorts of protective circuitry,including the usual thermal and S.W.r.

protection. It also contains a rather differ­ent fo rward power averaging ci rcuit. Thiscircuit senses forward powe r with a longtime constant. If the forward power aver­ages too high for too long, it activatesa.r.c. ci rcuit ry to reduce the PA output insteps down to 20 watts. Output spuriousproducts, including harmonics, we re at­ways below - 50 dB and sometimesranged down to - 70 dB.

Howeve r, the most interesting aspectof the transmitted signal was the thtro-or­der IMD products. They measured - 32to - 35dB from PEP using a two-tone testsignal. So, for all practical purposes, theKWM-380 IMD products are as good asany 100 watt class power amplifier usingthe ubiquitous 61 46B tubes, and there isno tuning. The KW M-380 contains an in­ternal power supply whic h can be strap­ped for input voltages ranging, in steps,from 105 to 250 volts. It can also operatedirectly from a 12-15 v.d.c. source. Us­ing the latte r, about 3 amperes are drawnin the receive mode and up to 18- 20 am­peres for 100 watt c.w.ls.s.b. operation.

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fai rly common in military and commercialcommunications spheres but practic allyunused by radio amateurs. It has beenthe standard Collins plug for many years.

Test ResultsTable I gives the claimed specifica­

tions for the KWM-380. To say the leastafter bench testing a unit, one should reogard them as very conservative if notdownright deliberately understated.

On the receive side, the KWM-380greatly exceeded almost all of its claims.The sensitivity ranged around the 0.3 to0.4 microvolt range for 10 dB STN/N ratioon s.s .b. throughout its tuning range.However, much more significant was theexcellent dynamic range. The thi rd orderintercept point for 20 kHz spaced signalsplotted consistently out in the range of+ 14 to + 18 dBm(usuallythe latter). Thesynthesizer noise floor could hardly befoun d with the test equipment available.An educated estimate has to remain atbett er than - 100 dB.

The synthesizer design is undoubtedly

a big part of the secret of the KWM·380'sperformance. Among other things, it al­lows the excellent shape factor of thes.s.b. filte r to provide meaningful resultsin practice. The stability was only mea­sured at room temperature rathe r thanover the temperatu re range specified. Avariation of only a few Hertz could be dis­cerned over an operating period fromturn-on to an hour or so later. 1.1. and im­age rejection exceeded 70 dB. And,where did all the "birdies " and spu riousresponses go that one often accepts asbeing normal with amateur radio equip­ment designs? I got tired of searching fo rthem. Perhaps there are a few of mini-mi.crovolt proportions someplace, but cer­tainty none are apparent. The 5 meter re­quires about 100 microvolts to indicate59. This is more than the 50 microvoltstandard for 59 frequently used, but ofmore importance is that the 5 meter re­sponse of the KWM-380 is tinear w ithin afew dB as signal levels change. 50, onecan provide a meaningful report to anot h­er station when testing antennas, aud iodevices, etc.

On the tr ansmit side, there is no ques-

Operating ImpressionsAs was mentioned befo re, the trans­

ceiver is reset to 15.000 .00 MHz when itis turned on. So, one first sees those dig­its appear rathe r impressively in thei r ap­proximate 1 inch height above the maintuning knob. The g roup of push buttonsabove the knob controls the tuning rate,locks-out the tuning knob from changingthe frequency whic h has been set, andcan be used to synch ronize the frequen­cies of the two built-in v.t.o.:s. Once onegets used to the rather strange symbolsused for the tuning-rate buttons, it israther easy to set up for operation , for ex­ample, on 21.195.00 MHz. One pressesthe '" button for 1 MHz increments andturns the tuning knob less than a full turnuntil a reading of about 21 MHz appears.One then would normally press one of ther buttons for a 20 kHz/knob revolutionrate to quickly finalize the frequency at21.195.00 MHz. It takes longer to writeabout it or to read about it than it takes toaccomplish it.

The Mode swi tch is used to select thedesired transmit mode, and the Passband

Say You Saw It In CO November 1982 • CO • 57

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IS' ""T""..•~>- ' .so ...., J' 1; "'"'" ,"" ,,..,..."" .." ... "",

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VOX ci rcuitry is very handy to set up forsemi-QSK operation on c.w. Used for nor­mal s.s.b. or c .w. operation, the trans­ceiver will run " cool" indefinitely. Thereis no cooling needed (except for extend­ed RnY ope ration), so operation is per­fectly quiet.

Accessory ItemsThere is an extensive line of optional

and accessory items available for theKWM-380. The internal mount optionalitems include WARC conversion, variousLt. fillers, a noise blanker, a speech pro­cessor, and a contro l interface. The out.board accessory items range all the wayfrom different types of microphones andheadphones to a blower kit fo r the heat­sink. Some items have been mentioned inpassing before, so only a few will be cov­ered in detail.

The WARC conversion consists of re­plac ing an ROM IC on a PCB within thetransceiver. The conve rsion requires theremoval of some 39 screws to get at therequired PC board. Some versions of thePC board have the IC socketed and somedo not. So. the conversion either can beextremely simple or require a bit of soro­ering. In any case, the conversion willresult in the frequency coverage changeshown in Table II. Note that the conver­sion not only provides for WARC cover­age, but also expands the 80-15 meterbands for MARS transceive coverage.

The optional speech processor avail­able for the KWM·380 is of a completelynew design and a patent is pending on it.It is an audio processing type, but hardlya simple compressor or clipper. In its lit­.erature. Collins concedes that the cener-

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Fig. 5- Block de /ails of the transmit chain in the KWM-380.

out. The sensation of using the main tun­ing knob to continuously tune is quitesomething. When one tunes from an indi­cated 5.999.99 to exactly 6,000.00 MHzthe fi rst few times, one expects all sortsof relays to resound, etc. In fac t, all isquiet and "bands" for the operator in apractical sense no longer exist.

The audio quality produced by thefront-panel-mounted speaker is perfectlyadequate for normal station operationand obviates the need for any accessoryspeaker (none is offered for the KWM·380). The various optional filters providefor just about any selectivity problem.But, one must face the fact that the KWM·380 does not offer true va riable band­width Lt. tuning nor a notch filter. Are theynecessary? I would say no if one pur­chases the various optional filt ers avatl­able for the KWM·380, but of cou rse, thisdoes become a pr ice question.

On t ransmit the KWM·380 consistentlyproduced comments regarding its goodaudio quality. It has signal " punch" butwith a "clean" sounding audio, used ei­ther in its basic configuration or wi th itsoptional speech processor (describedunder accessories). Perhaps one reasonfor this is its shaped frequency responseof 300 to 2400 Hz on transmit with only afew dB's level variation within that pass­band. Another reason is undoubtedly thesophisticated a.l.c. system used, whichkeeps the average to peak level powerleve l output closely linked.VOXoperationwas very smooth . Cw. operation was nottried as extensively as s.s.b. operation,but the KWM·380 appears to be as excel­lent a c.w. transceiver as an s.s.b. one.The separate C.W. Delay cont rol on the

" u,. >ELtct ===========~ Ju""" ..."" , " -.< , '" -­",4> -'<, - -

.",Tuning/Selectivity control is set to the de­sired receive sideband and i.t. band­width. There is nothing more to set up ortune on the transceiver, and it is "readyto go" assuming that one has previouslychosen VOX or MaX (PIT) mode, a.g.c.speed, speed processor in/out, etc. If onehas to adjust an antenna tuner, the Modeswitch on the KWM-380 can temporarilybe set to CW and the Mic/Carrier level con­trol used to increase carrier output whilethe reversed power reading is observedand the antenna tuner is adjusted for min­imum indication.

The tuning "feel " of the ma in tun ingknob is extreme ly good. It feels slightly" heavy," yet turns easi ly. The otherknobs are also very well dimensioned.For instance, the concentric AF/RF Gaincontrol knobs are not the disaster foundon some receivers. The RF Gain knob canreadily be manipulated, which c.w. buffsshould greatly appreciate.

If one set up the transceiver as men­tioned for 21 .195.00 MHz (with the v.r.o.switch at A) and then suddenly remem­bered a net on 3.897.50 MHz, it's a simplematter to set the v.f.o. switch to a, switch­in the appropriate tuning rate buttons,manipulate the main tuning knob a bit ,and be set up on 3.897.50 MHz. One canthen switch back and forth between thev.f.o. Aand a settings for actual operationor for just monitoring purposes. Thev.to:s can also be set so one controlsonly the transmit frequency. In otherwords, half-duplex operation can be car­ried on between any two amateur bands.If one presses the Sync button, the twov.t.o. frequencies align themselves, yetone can be used to control transmit andthe other to control receive. In fact, thiscan be used as a very sophisticated RIloption since the digital display will indi­cate the exact transmit/receive frequen­cies and one has independent tuning ofeach. One only has to remember that theKWM·380 will transmit in the s.s.b . modeas set by the Mode switch and receiveI.s.b. or u.s.b. as set by the Passband Tun­ing {PBn control. Of cou rse, once onegets used to the very flex ible dual-v.t.o.capability of the KWM-380, one wishesthere were a half dozen more suchv.f.o.'s so one could store various fre­quencies within a band and various qen­eral-coveraqe frequencies. In reality,such a provision is provided (see acces­sory items described next).

The impression that one gets as oneuses the KWM-3800n receive both withinand outside the amateur bands is its ex­tremely " clean" performance. There isabsolutely no hint of overload under thestrongest weekend signal conditions,and its uniform sensitivity makes it a com­pletely realistic general·coverage receiv­er as we ll as an amateur band transceiv­er. The "hang" a.g.c . action is excellent,being long enough in time constant tocombat QSB, yet not being too delayed toprovide ful l sensitivity once a signal drops

58 • CQ • November1982 Say You Saw It In CQ

Fig. 6- Block diagram of the circuit func­tions in the new type of AF speech proces­sor which is an option for the KWM-380.

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at consensus is that r.t. speech process­ing provides the best results, but withsome undesirable harmonic distortionand r.t.i. as inherent in any clipping ac­tion . They claim their method is as goodas r.f. processing without any of its disad­vantages. A block diagram of the proces­sor is shown in fig. 6. The actual physicalunit is a PC board measuring about41.4 "x 4 h • and contains some 13 IC'sand 8 transistors. A later article may ex­plore the concept of this item in depth,but the general idea, as shown in fig. 6. isthat the microphone signal is divided intotwo 90 degree phase shifted signalswhich are detected and recombined andproduce a d.c. signal proportional to thepeak signal at the detectors. The gain ofthe phase amplifiers is regulated to ere­duce an a.f . signal with peaks maintainedat a preset threshold. Harmonic distor­tion is claimed to be about 1Y2 % acrossthe 300-3000 Hz range for about 15dB ofvoice processing . From tests made withthe KWM-380 there is no doubt that theoptional processor does add somethingin the order of 4 to 6 dB of apparent in­creased signal intelligibility with no ap­parent distortion. It works and works ex­tremely welt, but whether it is the idea l so­lution to the question of speech process­ing remains open. In any case, it is anoutstanding advance in audio-type pro­cessing .

The Control Interface option is innocu­ous sounding. but it adds tremendousversatility to operation of the KWM-380.The option itself consists of a PC boardassembly and a connector which is for ln.ter -connectlon with a user-supplied ex­ternal key pad (any sixteen button, two­out-ot-erqbt device) or possibly a homecomputer with parallel interface capabi!i­ty. In any case, the interface allows forthe digital selection, storage, or recall offrequencies (the storage/recall capabilitybeing either 10 or 11 frequencies, de­pending upon whether the WARC optionis installed).

Using a key pad, the operating fre­quency can be selected from either themai n tuning knob or the keypad.One sfrn­ply enters the frequency desired digit bydigit. The frequency being entered on thekey pad is displayed, but the transceiver's I

operating frequency is only changedwhen an "enter " key is depressed. Theinterface PC board contains memory lo­cations for 10 (or 11) frequencies inde-

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CIRCLE 24 ON READER SERVICE CARD

eo Say You Saw It In CQ

Table 1/- Transceive frequency coverages of the KWM-380 when the S8 10 WARe op­tion ROM is installed.

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postcard reply form which will put thepurchaser on automatic distr ibution forall future service bulletins as long as theKWM-380 remains in production. Quite afew such service bulletins were issued upto January 1981, The last one containedin the manua l reviewed was dated August1981 and was only info rmation on WAReconversion.

Deale r and fac tory service for theKWM-380 is available and there is a one­year warranty. Those restric ted to cer­tain APO/FPO addresses. howeve r,might note that the KWM-380 is too large(with packing) for Parcel Post shipment,and freight shipment must be used.

The KWM-380 can be remotely controf­led by a key pad such as the one shownhere (or a similar one supplied by theuser). A control interface cotton has to beinstalled in the KWM-380 to use the keypad, but then one will have key-pad con­trol of frequenc y entry. storage, and reocall. If one imagines the key pad on theright of the trom-oenet view of theKWM-380 showing the microphone onthe left. one has a comoetetv integrated,

automated h.f. station.

SummaryThe KWM·380 is an outstanding piece

of equ ipment . It offers ex tremely sophisti­cated operating capabilities using state­ot-the-arttechnoloqy. but without a frontpanel so c luttered with knobs, push but­tons. and switches that one misses out onthe fun of operating whi le trying to figureout how to operate a tra nsceive r. It is notinexpensive. But, its design concept issound, and, as RockwellfCollins is willingto put in black and white, " No yearly mod­el changes. As circuit improvements andmodifications are made to the KWM·380.its style does not become obsolete." II

14.0 10 14.35

28.0 to 29.7

2 1.001021.45

Without $B 10 (MHz)

1.BI02.03.5 10 4.07.010 7.3

Band (Mltlrs)

160BO40so201615t210

pendent of the two v.f .o. registers. Tostore any frequency, it is entered by key'board selection and addressed to a de­sired memory location (e.g. , 1,2,3, etc .).The transceive r can continue on its tun ­ing knob selected operating frequency, ifdesired, during the process. Or, the cur­rent operating frequency can be storedby a store and memory location key padcommand. Recalling a frequency con­srsts ctpressing a recall key and a memo­ry location. This action loads the storedfrequency into the v.t.o. reg ister in use (Aor B) and sets the transceiver's operatingfrequency to the reca lled frequency. Onecan also use key pad commands to man­ually step the transceiver through eachmemory star ting from the present memo­ry location in use . Blank or cle ared mem­ory locations are skipped during the man­ual stepping process.

The key pad frequency cont rol optionObviously adds all sorts of operating pes­sibillties to the KWM·380, ranging fromserious DX chasing across several bandsif desired (remember, the re is no band­swi tc h) to switching to a news programdu ring a boring net session. Removingpower from the transceiver will clea r allmemory locations .

Manual and Service NotesAn operati ng manua l does, of course,

come with the KWM-380, and it con tainsvery clear, practical information for get­ting the uni t into operation. It has a multi­tude of photos and illustrations all direct­ed towards telling the operator hOw 10

hook up the transceiver, which controlsto turn for various functions, etc. It alsocontains a limited amount of informationon maintenance and some PC board in­terconnection data , so jf a PC board is ex­changed. one can understand wh ich In­terconnecting cables are involved.

A separate, outre elaborate servicemanual is ava ilable for about $40. Thismanual is extremely complete with thor­ough information on PC board layouts.schematic diagrams, alignment and testdata, etc. Complete parts data is givenalong wit h the name and address in theU.S. of the manufacturer of every compo­nent used (except common resistors, ca­pacitors, hardware, etc .). The manualalso contains a complete set of servicebulletins issued for the KWM·380 and a

Say You Saw It In COCIRCLE 11. ON READER SERVICE CARD

63