Our New Cs Dual Password

TTïir K*!Zuf)0 MX 6Z

toi the mjgs'ng into ; here were also so™ 3ugge?ied modification* n the Japanese instructions such t, 3n s^nifltef ithough I don t know where you d moun" a transmit lighi anrt j CW Sldetone. which aren't m the English version The two circuit boards were already assembled, tested, and mounted leaving only a little wir-ii- ; uki assembly to do Two iypes or battery holder were provided; a 9-volt tran-sistor-batiery connector, and a holder tor AAA cells i recommend Ihe latter, since iihe uni! draws enough ..urreni to deplete aimosi any 9-voll transistor battery ta short ofde*

Both units worked is ¡^oon as power was applied, and no rune up .was neces-inst'uc on1 were prt wtded any-ii:-. r.:!ia lest ■■ be ■ supplies showed a need 1 ■ r j iitt e more bypassing 'ne eaternal powi-t r-:iLH .a:- or the bottom of the case &«Ke the supplied ex-lernai-power cord was radiating more than my dummy load! A 001-uF ceramic across the dt-inpul terminals Quieted things do a n One unti put 275 Watts into Ihe load on CW and SSB voice peaks, the 01 nef a illte less. However bolh dre a 22t m A from the 9-V supply while doing it. Cur ren: dra n on receive is about ¿0 mA. and TOO mA during key-up transmit A regular carbon-zmc transistor battery went flat very quicki> under Ehe strain so f switched to alkaline AAA cells whim have held up preiiy well in lighl usage A separate power suppf> or external battery pack Is really necessary for any serious long-term operating. It looks to me as if n battery pack from ah iCOM 2A would tit perfectly on the bottom ol ihe case it ii could be attached securely, initial tests in the field (literally a Hetdi) snowed that the little uni is have 3000 audio quality anp frequency stability on both transmit and -eceive The 11 inch "super ¡rubber ducky antennas supplied gave perfect copy at a rangp ol a halt mile Aith a hill and budding in beiween. The tuning is on [he top ot the case and conirols a variable crystal oscillator wi|ti a range of 50 kHz. A 'band1' switch next to il switches between either o? two crystals [one is provided, for 50,2 to 50 25 MHz*, giving it a total of lOOkHzol coverage The necessily of tuning in the other station and the liick of squelch are a little strange at first whan your only other hand held experience Is wilh 2-meter FM. Perfectly normal on HF sideband, hul uhcxpfrMed in a handle, The iransmit button Isn't a push lotalk type. It's a latching swilch— push once to Iransmit, again to receive Sm e the MX-6Z aiso transmits CW Hrom a liny button on the lop panel or through a miniature tack on the bottoms this does ma*e some sense. The internal micro phone is an elect ret type, and there an externa I mike jack on top ot the caie to the headphone jack. A noise*tanker let" below the tuning knob, ^nn thf: blanker does seem to work pretiy weH on ignition noise an impon^ni consideration on st* meters.

As you'd expect in any unit th.il packs this many features into so small case, the circuitry is pretty simple. One of ihe

1 wo PC boards is devoted to rf and the Other 10 M, sideband generation, and audio. The receiver is a single-conversion lype wilh a Hxed-tuned dual gale MOSFÈT tt-amplifiai stage, I measured ihr> sensitlv ty icrudeiyt as aboul 0,6 utf tor 20 dB sig nai-to-noise: î could near a signal at O.i uV. The i-f frequency is 7 3 MHz and the liny cry stal filter seems adequa;« on both receive and transmit A jutck .^nd dirty check Showed a 6-dB bandwidth ot about

2 kHz tram rf in to speaker out The frans-minfir has three "power amplifier ' stages following The transmit mixer me tirsl of which is a dual-gate MGSFET which is keyed for CW Allol ihe stages are broadly tuned and inductively coupled excepi ihe final which is a multi-stage pi lype Trans mii-receive switching is done *ith diodes ana is accomplished with a closure tc ground so CW brealtáti aperation might be possible with a simple modification Audio output and quality is pretly mucn on a par wilh othe^ nandie talkies wiin an LM336 audio-amp IC driving a two-inch speaker

The besi part of this little rig is that it's fun1 It roally works pretty well roí its low power. When six is open, noi much power Is needed of course. and when the band is closed, not much will help Onaot the tirsl contacts i made alter builoing and testing my MX-6 was with a south Texas station, followed by contacts with Oklahoma and Minnesola all between 800 ana 1000 miles Irom my Tennessee QTH This was done *ilh in 8Cmeter dipoie mee I didn ■ have a Sit-meter antenna up' A

propyl antenna and more power would help a lot QRO is available in ihe lorm ol a 5-Watt amplifier, the PL-6

Ultimately, ihis title riß is likely ic be used for portable or mob.le work suet' as mountamtopprng Its small tuning knot and limited inning range, to say nothing of its low power, will not make it a favorite of hard coro 314-meter operators, bul II 1?. .1 nice cheap way to flet on sii-ni^t^r sideband. I uso mine mostly for local monitoring and checking for banti openings, tasks for which ihe rubber-ducky antenna works fine When aciivity occurs 1 can hurry 10 ihe shack and plug in Ihe outside antenna and sharpen up my QRP ©per ating sMIls One oí these days l m going tc get a portable six-meter beam and hike up .mo the Smo* ey Mountains ana nope tor a band open.ng. Then thí MX-6 wiM reaiiy be m its dementi

For turtfier information, contad Ace Comrmjn 1 c<> tto ■"S 2832 D Wa tru! A. ■:■ Tustm CA 92680 '7 U-5*4-828J Rr-ader Service number 477.

Mark Nelson AJ2X Knokviile TN

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