A HIGH- PERFORMANCE 2-METER TRANSVERTER
Modular approach Receive strip The receive side input (Figure 2) is a GaAsFET low-noise makes construction amplifier (LNA) that uses a circuit similar to Reisert'sl and to those in general FET applications notes. The device is a sin- and modification easy gle gate MGF-1402 made by Mitsubishi; it's available from several sources.* The 10-k resistor on the input bleeds off static buildup. Any value around 10 k will work, as long as you use a carbon composition resistor. (I had a persistent and elusive By Bob Lombard;, WB4EHS, 1874 Palmer Drive, oscillation; it wascaused by the metal film resistor I was using!) Melbourne, Florida 32935 I used diodesaround the regulator to protect against regula- tor latch-up or inductive spikesfrom the TIR relay. The ampli- fier had a noise figure of under 0.75 dB and a gain of 23 dB, as measured on an Ailtech noise figure meter and HP network analyzer. The filter (shown in Figure 3) was described in an earlier arti- t seems that many VHFIUHF enthusiasts say they became cle.2 I wanted the filter to be narrowband enough to pass all interested in this part of the spectrum after having worked 4 MHz of the band, and still provide over 40 dB of rejection Ijust about all of the DX available on HE This wasn't thecase at 162.55 MHz. It provides nearly 55 dB, at acost of about 5 for me. The possibilitiesof 2-meter operation appealed to me dB of insertion loss. At this point, however, there was gain to on their own merits. There is OSCAR, moonbounce, meteor burn to meet the design goals of about 10 dB of gain in the scatter, SSB, CW, and a host of propagation modes to explore. complete transverter. My interest in these modes of communication led me to A 116-MHzovertone crystal oscillator provides the LO func- review their requirernents. I realized that commercial rigsavail- tion for both sides of the transverter (Figure 4). The oscillator able at the time didn't have the two main features I was look- is acommon base design, largely based on Reisert.3Theout- ing for - a low noise figure and a selectable CW filter. Like put was measured at +13 dBm, allowing the useof atwo-way many before me, I decided to build a transverter for my HF rig. power splitter to provide LO to both mixers. These were my design goals: The receive mixer isa Mini-CircuitsSRA-1000 (see Figure low noise figure, in keeping with the state of the art; 5). It is essentially the same as their SRA-1 in this application. output power in the range of 5 watts, with excellent linear- The IF output goes into a diplexer and 24 to 34-MHz band- ity (third-order IMD at least 30 dB down); pass filter. In band, the diplexer (the parallel-resonant circuit good rejection of a nearby NOAA weather radio relay (at and 51-ohm resistor) presents an open circuit, and no signal least 40 dB down); flows in the resistor. As the frequency changes the reactive moderate gain (enough to overcome the front end noise components tend to short out the tank circuit, allowing signal of the HF rig); to flow into the termination and to ground. The mixer sees the good dynamic range. 51-ohm resistor at these frequencies. I adopted a modular design approach advocated by Joe The receiver input stage is largely responsible for determ~n- Reisert, WIJR, and others. I l~kethisdesign because it gives ing the system noisefigure, and the noise figure isdegraded me the ability to get sections working and tied together by any losses in front of it. If you're new to the field of low-noise quickly. This, in turn, makes the project seem less like a con- design, thisexplains what must seem like the unconventional stant uphill battle. Also, the modular method with its replace- design of the transverter; i.e.,the amplifier ahead of the filter. ablesections isagreat benefit when you come up with a bet- (This is a common design technique in microwave receiver ter design. The block diagram of the transverter appears in Figure 1. 'See parts sources at the end of the artlcle Ed
68 ' Ham Radio/Jul)/ 1989 I RF AMP BP FILTER
BP FILTER PTT -
RCV OUT -
N/C MIXER MIXERS +lZV A- S Wl TCH Tr IN
N/O
+24V +12V +12 V
L P FILTER PA DRIVERS PRE-OR1 VERS
Block diagram of the complete transverter.
10f
CI = 5pF JOHANNSEN PISTON TRIMMER L 1 = 8 TURNS #20 3/8 0.0. AIR WNO. T1 = ST BlFlLAR #34 ON FT-23-63
SOURCE 2
-0.01
Schematic of the receive input RF amplifier. design, likeTVROs.)Tominimize theeffectsof losses in front predominates.While this maybe true, my idea all along was of the amp, I used foam-flex (hardline) coax as the feedline, that receiver noise shouldn't be a limiting factor if I wanted to with short flexible jumpers of RG-2141U where required. swing my antennasup for OSCAR - or anything else I might Other hams have told me on the air that my low noise fig- try. When you add that to the high intercept point of theGaAs- ure is unnecessary in 2-meter SSB because ground noise FET front end, and the resulting improvement in dynamic
Ham Rad~o/July1989 69 ALL COILS COILCRAFT 7-113 1 I/.? TURNS 68nH WITHOUT SLUGS RESONATING CAPS 2.5-lOpF VARIABLES IN PARALLEL WITH lOpF CERAMIC COUPLING CAPS 0.25 - 25pF TEFLON TRIMMERS
Details of the BP (bandpass) filter on the receive line.
0.001 78M08 - - 0+12V I- fZV 1
4.7pF 4.7k < NPO a a SIGNAL FB 10 m I 0.001 m YI lh L1.= 8 TRNS #24 CLOSEWOUND ON (1 7- II) = 4 1 0.100 FORM fREMOVEOl FB = FERROXCUBE #56-590 loo' 65/4A6 0.27pH NPO Y1 = 116.0000MHz 5th OT INT'L CRYSTAL
Local oscillator using a 116-MHz overtone crystal.
Parts list llca :APACITOR 0 mica Electrolyti 0 ceramic 1.5 11N1 ceramic 'I r,. Q r.r., pr, r J lYllJ I ,?adlo Shack 272-1435 u.u-, " 4.7 /lN15 Volts 3 i!72-1024 'Most of these came from my junkbox. the result of years I 10 pF/3ti volts 1 i!72-1025 hamfest ttuying. Try (:ommunicac lions Concepts, Inc., an~d other! 330 pF/116 volts 1 ;!72-1030 (4; Some of these coulu1 be made irvto more parts of one Ivalue. Ceramic,-- - Imonollthlc (dipped, 50 1 08 pt - 470 pF t carbon ca 5 percent 0.001 ,L1 thm 0.01 ,&F ~hm 0.1 /!F thm Cerarn~c.monolithic dipped, 50 volts (COG or NPO) 3.9 pi 4.7 PI 10 pF 27 pF 39 p~ 1 2 47 pF t carbon ca 2 270 pF bhm -all values Trimmers, ~hm 0.25-2.5..- - -. -, Teflon 4 UP r~rrers 0.5-5 gl, 1 GaAsFET amp 1-watt (:arbon cornposition. 5 percent 1-5 pF c 5 62 ottm 2 2-20 cer 5 68 otIm 1 Receive and transmit mixer schematic.
It carbon composition MISCE iLLANEOUS "'"-C Ferr ites as coil for1 value over 100 k (used m) FT-2'3-63 1 Amk kn snt . I-watt carbon composlt Ion, 5 percc Beac us, terroxct- )be type 4A16 4 Amic kn(cross-I ohm 2 Two-hole balun (for RFC or I drlver ass embly) " -&.- A - ~ -a. " v,,r,, BLN' 43-2402 ;1 Am11 ohm Ferfioxcube VK200-19/48 1 Amic srerence) D ohm TOROlIDS T44-6 2 Amk ion ---- T20-10 2 Amic ion .. . .> ,- -.. ..----- 1N4 148 gener .a1 purpose 6 (wldel ore: The exact ferrite beaaI usea m mosr cases rsr.--)'t crftical. 11 I 1N4004 rectif,ier 1 should present se veral micro1renries of inductance a)t the operat. IN757 9-volt ,zener 1 ing frequency. 1N751 5-volt .zener 1 OTHERPARTS ,ansistors .1 mixer ners 2N2222 NPN - 1 2N3553 NPN lrts Compan -2-1 power . hen 2N5109 NPN ~rtsCompar: IHz fifth ovc rrts compar- 2N5179 NPN ultiturn pot I naoro anacn Asrc I 1 RF Pa ~rtsCompar ower switct ,It 1 Radio Shack (erFET rrts Compar axial relay 1 Communications Concepts axial conne 15 SMA female (as required) OTHEI a1 jumpers (as required) MW.4-130 amprifler modules z communrcarrons wnce~rs YVIFl (as required) 95 5-volt regulator 1 (widely avallablc Feedthrough cap 0.007 ,IF 50 volts 18 or ISM08 8-volt regulator1 (widely avallabl~ (as required. 1 per box) 31 1 comparator 1 (widely avaiiablc lOpH molded chc 2 MWA-130 MWA-130 (025-2.5pF)
RF OUT
68nH lOpH lOpH
0.001 IOOD 1/2 W
Transmit predriver schematic.
'," 0001 Ll = 3 TURNS #16 1/4 ,n I0 - 0+12v LZ -- 4 TURNS #I8 3/16 rn I0 15k L3 = 4 TURNS #I8 I/l rn I D ,62n I * IN4004 MOUNTED IN THERMAL - - CONTACT WITH 2N3553 62 52 1W 5- UO~F
l 1 RFCl ::56k I
2N5109 0 RF IN 9-35 Ll 470 \I A A m
Driver chain schematic. RFC 1-4 = 4 turns of no. 20 wire through a two-hole ferrite balun. Amidon no. BLN 43-2402.
range, the GaAsFlfT still seems the most logical choice. all of the signal lost in the conversion, provide enough filter- My initial test of the receive side yielded good results. While Ing to remove significant power on the imagefrequency,and conducting tests with WA4GHK (15 miles south), it waseasy reduce LO feedthrough. I used MWA-130 amplifiers, modu- tocopy K4DZP in Miami (over 160 milessouth) - despite my lar 50-ohm in-and-outdevices in TO-5cans, because they are makeshift indoor antenna! easy to use and were available on a surplus board that I scavenged. The power out at this point is 4 mW (+6 dBm). Transmit chain The actual drivers are two transistors, a 2N5109 and a The transmit portion of the transverter presents itsown prob- 2N3553 (see Figure 7). The first device is a well-known VHF lems; the biggest is linearity. A rule of thumb for diode ring linear transistor; the second isa28-volt,TO-5 can devicecapa- mixers(liketheSBL-1 used here) isto have the input signal at ble of 2 watts if run class C. This was originally to have been least 10 dB below the LO for best linearity (see Figure 5). a three-transistor strip with 1 watt out from a third 2N3553, but Because one of rriy design goals was to achieve very good I was never able to get them to more than 500 mW and still linearity from the transmitter, the first thing I did was pad the remain linear with a 12-voltsupply. I tried many variations of input drive (+3 dBm) from my HF rig. The resulting level was bias circuits, matchtng networks, and pc layouts. The two- about -7 dBm, 14 dB lower than the LO drive. Since all the device strip I settled on produces 18 dB of gain, or about 250 pads were made with the closest value resistors, and the mixer mW out. Itself contributes loss, I measured the conversion loss of the The final amp is a Motorola MRF-134 TMOS powerFETthat transmit mixer. It was 17.7 dB. delivers just over 4 wattsout and a clean, linear signal (third- The pre-driver stage in Figure 6 is suppposed to recover order intermod down just over 30 dB). See Figure 8for details.
72 Ham Radio/Juiy 1989 New from ARRL
/ IMPEDANCE HATCHING ( Following the hard-cover style of Transmission Line Transformers, and Yagi Antenna Design, Antenna Impedance Matching is written with the advanced amateur, antenna design engineer and tech- nician in mind, but even if you don't have any special expertise you'll be able to develop very sophisticated systems. This is probably the most comprehensive book ever written on the use of Smith ChartsT"in solving impedance matching problems. This 224-page book is of importance to those who want to maximize antenna effectiveness. A properly matched antenna as the termination for a line minimizes feedline losses, and power can be fed to such a line without the need for a matching network at the line input. Antenna Impedance Matching is a "must" for the antenna designer and serious amateur. The price is $15, please add $3.50 for shipping and handling.
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Want to design an antenna just for you? *Need a program for design and plotting? *Need to solva a unique problem? -Know the best antenna for hamsats,etc.? *Need a disguised mobile antenna? -Want a cheap automatic coupler system? *Just want to learn more about antennas? THEN SUBSCRIBE TO - antenneX0 12 MONTHLY ISSUES is only $1 1.97 for USA and possessions. $17.00 foreign. antennexo PO. Box 8995 Dept 19 Corpus Christi, TX 78412 Fmq. 1 d~ R.~eh Range N.F. Qaln Comp. Dorb Only (MHz) (dB) (dB) (d8m) Type Prlco P28VD 28.30 c1.1 15 0 DGFET Electronic Repair Center PWVD 50.54 c1.3 15 0 DGFET PWVDG 50.54 <0.5 24 +12 GaAsFET P144VD 144-148 c1.5 15 0 DGFET Servicing P144VDA 144-148 ~1.0 15 0 DG F ET P144VDG 144-148 c0.5 24 +12 GaAsFET Amateur Commercial Radio P220VD 220-225 ~1.8 15 0 DGFET P220VDA 220-225 <12 15 0 DGFET P220VDG 220.225 ~0.5 20 + 12 GaAsFET The most complete repair facility on P432VD 420-450 < 1.8 15 -20 Bipolar the East Coast. P432VDA 420450 cl 17 -20 Bipolar P432VDG 420450 c0.5 16 +12 GaAsFET Large parts inventory and factory authorized warranty service for Inllne Ifl rrritchmfl SP28VD DGFET Kenwood, lcom and Yaesu. SP50VD DGFET SPWVDG GaAsFET SEND US YOUR PROBLEMS SPl44VD DGFET SP144VDA DGF ET SP144VDG GaAsFET Servicing "Hams" for 30 years, no rig SP220VD DGFET too old or new for us. SP22OVDA DGFET SP220VDG GaAsFET SP432VD Bloolar SP432VDA polar SP432VDG GaAsFET 4033 Brownsville Road Erny pmamplltlw la prmchhm rllgrwd on ARR'e H.rkn P&rd HPW7MMP34Mat--- ndr nOur Trevose, Pa. 19047 meter. RX only pnam Ilflen ere lor 18~0lveep Ilcatlonr only. Inllne pmampllllen am rl ewltchod (for us* m w~thtransceivers) an8hand1e 25 watts transmiter power. Mount inline reampllflars brtween transceiver and power ampllfler for hlgh power eppllcatlons. Other amateur, commerclafand s clal mampllllem available 2 15-357-1 400 In the 1-1000MHz range. Kasernclude $2 ah1 ping In U.S. and Canada. Connectlcut rssldents adt T.'lz% - sales tax. C.O.D. orders add 12. Alr mall to foreign coun. Rdvanced trles add 10%. Order your ARR Rx only or Inllna Receiver preampllller today and start hearing Ilks never before! Research Box 1242 Burlington, CT 06013 I 2 METER AMPLIFIERS .ATV CONVERTERS DISCOVER THE WORLD OF FAST SCAN RF Ampliimr Pel Motor& Buklmr TELEVISION cm*. P",, s(l far a 110 Watt I3W wnl Hi Ammr *r M"lW.1. 8vhll"l ,', AN-150 AN-262 El-llA EU bI RWNWHD TAANWmUEIS PSfl U111W30(aHOLIFIINI %!kQ'bf:%u-"h 4Iuh 100ub I lm UIIlR2 5%~ 1 081 0.1 M." Wt Aha St-t Hnd-1.-Fd P*1. TELEVISlQN_CO~1VERI@S 581-II 001 Ud Mlln ATV 2 110 150 UHI a 14 91 #I REMIT CHIP CAPACITORS MITALCLAD MICA CAPACITORS rrv I 110 150 NHI '.A. I., 1 1~9% " chQ" I lrn ATV-1 PO1 918 VHI G.A. #.I 1 59P5 II VK'M ' 5EMlCONDUCTORS %6 5PO 65 10 fnld. L.4 I 20 Rf POWER TRANSISTORS POWfR>PlJ~RlCDMO~ Fa &I.M hlarrnalbm pkne Aralbbk n Ra r AsurnbW/T.~W 2-10 MHz 600 Walls ( ? Po11 ar 1 Pwl I ----R FC h * - 0 24V + $o.ol pAVF x 0.001 2.4-50 RF IN 2.4-50 u' f RF OUT (24 WATTS, 2-8 L1 -3 TURNS #I8 0.3in. ID. CLOSEWOUND 6852 1W RES IS COMP OR FILM LP =4 TURNS #18 0.3 tn 1.0. SLIGHTLY SPREAD RFC =7.5.~tHWOUND ON LARGE FERRITE BALUN CORE OR FERROXCUBE VK-200- 39/46 L3 -20 TURNS C20 ON ZW CARBON COMP L100k Final amplifier using an MRF-134. All design decisions are tradeoffs. For example, using the MRF-134created the need for a small 24-volt supply - but 65n H 55nH I gained advantages rn other areas. First, the FET is guaran- teed to deliver rated power into a 30:1 VSWR at any phase 1.6 4.7 T w angle(no delicate device here!);second, it'scapable of more 9 I gain in one packagethan a bipolar; and last, ~tworked the first time I tried it - a very enjoyable experience after my trials and tribulations with the '3553s. m /h m Thecircuit is taken largely from the Motorola RFData Book I BOTH COILS WOUND AS 2 TURNS XI8 0.310 in 1.D. applications note.4 Component changes are based on avail- ability and personal preferences. In any RF power amplifier it's essential to keep the ground leads of the device as close Schematic of the transmit LPF (low pass filter). as possible to ground on the board. I connected top and bot- tom foil with a strip of copper shim stock at the point where for the GaAsFET RF amplifier, filters, and all transmit stages. the source leads leave the device package. The FET itself is The LO, mixers, and theTIR switching boardsare built "dead on an extremely overrated heat sink; after extended key down bug" style; they function quite well that way. If you are an periods everything remains at ambient temperature. experienced builder who uses point-to-pointtechniques at Theoutputfilter in Figure9 isan elliptical low-passdesign. these frequencies, you may want to use that method. I used The two parallel resonant circuits are tuned to 313 and 487 SMAconnectorson small-diameter coax (RG-188)for signal MHz with a grid-dip meter; the other caps are adjusted for interconnects. You may prefer to use BNCs. Likewise, I used minimum insertion loss while you watch output power on a pc board material for housing circuits- you may prefercom- wattmeter. My version had a measured insertion lossof under mercially made enclosures. 0.2 dB. I'vealready mentioned the need to keep grounds short on I used asimple comparator on the PTT llne from the HF rlg the final amplifier; the same holds true for the driver stages. to do the TIR switching (see Figure 10).The relay is DPDT It This is the strongest argument for using pc boards for these switches 12 and 24 volts to the transmit amplifiersand 12 volts stages. The emitters of the driver transistors are grounded to the antenna relay (a Dow-Key relay I plcked up at a local Immediately, with minimal lead length. hamfest). The relay prov~desover 40 dB of isolation during There are no "peculiarities" of alignment. Align the filters transmit; theGaAsFETsees -4dBm, well within itscapabili- separately, tuning them asdesired. It's best toalign the trans- ties. (I leave it powered on continuously.)This relay should be mit stages with a spectrum analyzer. Tune the driversfor best adequate at power levels of up to 100 watts. output while observing third-order intermod. This will not occur at maximum power out. The same applies to the final Construction and alignment amplifier. This is a sophisticated project and you'll need building Ideally, the GaAsFET should be aligned with noise figure experience. If you've had experience with other RF circuitry, instrumentation.If that isn't available, tune for maximum noise you'll find it presentsfew special challenges. I used pc boards level by ear, and then detune slightly. The optimum noisefig- Ham Radlo/July 1989 75 WlDOWN EAST MICROWAVE MICROWAVE ANTENNAS AND EQUIPMENT .~oop Yagls Power Dlvldem Llnerr Ampllflen - Complete Arrays. 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Si mply plug into receiver's antenna 7031894-5777 vlsalmc 8001282-5628 and exter~~a~----, apadker---- lacks. Uses four ornnidire~~,~,,,,.-.+,nnnl~,,,ennas..,n+ Low noise, high sensitiv ity for wee~k signal detection. C:all or write for full cletails and prices. 31819 OPPLEli SYSTE:MS, IN( 2. P.O.Box 02) 488-9' Phoenix, AZ 85046 (6 Tell 'em you saw it in HAM RADIO1 TO TR RELAY DRIVERS +12v +12v TO PA + PREDRIVERS PTT LOW -1 lk IN4148 ACTIVATE 10k TO LO. 8 RF AMP. TR SWITCH +24V +ltV Parts sources TIR switch schematic. DI~I-Key ure match isn't far from max gain, but that's about as quan- 701 Brooks Avenue South. PO Box 677. titative as I can get. Th~elR~ver Falls M~nnesola56701-0677 A broad l~neol passives, sem~corirluctorsand tools Performance Mln~-C~rcoils PO Box 350166, Brooklyn. New York 11235 0003 On-the-airresults have been good. I actually used the trans- M~xersspl~tters, hybr~ds. elc . wltl sell to ~ndlvlduats verter for quite a while at the 250-mW level, and surprised Am~donAssoc~ates myself by working most of peninsular Florida. I made some 12033 Otsego Streel, North Hollywood Cal~forn~a91607 of my best contacts with an indoor antenna and the pleces of Toro~ds.Ierrlles. ~nducl~vecomponents my project spread across my desk. Moving up to 4 watts put Cornmun~cal~onsConcepts Inc me within 3 dB of the mainstreamof off-the-shelf2-meter SSB 121 Brown Street. Dayton. Ohlo 45402 rigs (that's about half of one S-unit),and to a level that could RF parts and kits, hard to~flndlrlrnmers. chip caps. Irans~slors.ATV parts be used with commercial amplifiers. It also netted mecontacts RF Parts w~thfive southeastern states using a small antenna at rooftop 1320 Grand Avenue. San Marcos. Cal~forn~a92069 height. RF power dev~ces.GaAsFETS. and many other lranslstors I'd like to thank Jim Hagan,WA4GHK, for his part in thecon- REFERENCES 1 JoeRn~wrl,WIJR Low NolseGakFET Technoloqv HdrnRarlro Decrlnltrr 1!384 11;iq*r;~4'l112 ceptual design of this circuit and for helping me with on-the. 2 Boh Lnml)nrd#WRJEHS Butid Narrowhnnti Filters Ham R,lrl,o March 786 paqcs 10 ?1 air tests. 3 JoeRrlserl WtJR Hlqti r)yn;~m,c Rnnqr on 2 Molprs Ham R~I~II'Nrrw?mtvr 1qHS uaijec.54 64 4 Techntcal Slat1 rcl Molorola RF Device Dala Book A~~zon;l1986 - ...... : .:-:.. :-3 fi 4 r.; ?:" :5e, ;.: .-* ;,::., :.t?-- -.~' ;;-7 MODEL ,>r,q.2h,. ]lr,l~~l"p- SG-100F ...- >+ ,,=?-,,C,, ->>?. - <.C'j'> - 'a':' vb7,. LOGWRITE'" MADE IN 5429 95 r8r.q .,,+!,.1 .; . *r) t~ I 01 -11 I IIUXII 14q 41% cxt %I In ordcr rtlh Vnn Mwcr Call or write for details Phone in your i mrd {Pkac specnfr 1% or % 2% tnch fbppv I order for fast COD shipment. -- I .I .. v VANGUARDLABS :fin.,r .+.,-.., '..':.'"5'7 196-23 Jamaica Ave.. Hollis. NY 11423 7-, -(,t, r,:,:x. Phone: (718) 468-2720 Mon. thru Thu.