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f, title like this usually implies that the.Cl. author has severul PhD's and orvnsshares in the local aluminum tubing industry.The reader, in the end, is left with his en-hanccd Novice privileges, a wire dipole on I 0meters and a hole in his pocket. By way ofcontrast, this author just wants to share asuccess story on what to do with the gift of anon-working television antenna.In the Beginning

It all began one day when the XYL walkedinto the shack and said, "Honey, I knowthat you are having a great timc on ten mctcrsbut wouldn't it be better if you had a tri-bandbeam like those other guys'? What do theycost?" My response elicited, "Oh! Thatmuch? And you'll need a bigger rotator?"A good hard look at Orr's Handbook, , are-examination of an old TV antenna, and adiscovery trip to the junk pile in the woodswith tape measure and pliers lollowed. GotdlWell, nearly as good: another (very bent) TVantenna, a ten fbot pipe, and a five-and-a-halffoot section of steel tee-stock.The Handbook had a description of a two-element yagi that couldgive 5.5 dB ofgain anda front-to-back ratio of7 to 15 dB. The secondelement, the parasiticelement. could becomea reflector-in whichcase it should be about5% longer than thedriven element-or adirector if cut about 5 %shorter. Using the para-sitic element as a direc-tor gives slightly moregain and the advantagesof a shorter elemcntwith the mechanical ad-vantages of reduccdweight. turning radiusand wind load.The Handbook yield-14 73 Amateur Radio o

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ed the following formulas;Driven Element Length (feet): 416 + frequency (MHz)Director Length (feet): 450 + frequency (MHz)and Elernent Spacing (f'eet): 120 + frequency (MHz)

Assembling the IlaterialsA 28..+00 MHz center frequency (thephone sub-band) required about 16' 9" forthe driven element. 15' 10V+' for the direc-tor, and an element spacing of4' and 3".

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Disassembly of the inherited TV antennprovided a 13' piece of one-inch aluminumtubing; l0' of one-inch galvanized pipe;couple of piece s of 3A " aluminum tubing 45long; and several pieces of %" aluminumtubing between 36 and 48 " long held togethin pairs by mounting brackets. The harvesincluded a handfull of wing-nut bolts, a cople of bakelite blocks measuring 1" by 2" bt/2" , rwo usable u-bolts with nuts and lockwashers, an assortment of little brackets, antwo chunks ofboom from the second antennthat could telescope into the water pipe.The various bits and pieces laid out werevidence that a ten-meter mono-bander waabout to take shape. Ifthe new antenna woulbe small and light enough, that small Trotator could handle the additional load.A pair of the % " diameter tubes attached teach end of the 13' former TV boom wit7+"-20 bolts yielded a driven element morthan 17' long. Connections with U-bolts enable length adjustments without cutting.The ten-foot piece ofpipe was stretchedsimilar manner. A couple of leet of aluminumtubing were telescoped into each end ansecured with bolts before adding the formeTV elements.The tee-stock wanext drilled to accommodate a two-foot triangle of counter-top material that had bee"weather-testing" behind the clubhouse. Ater adding a pair of Ubolts, this assemblprovided a securmount to the mast.

Antenna MatchingThree methods omatching were avaiable. The Delta-matcwould have requiredmatching section abou

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E for minimal nfi/fi f.;'.t""-i",1d4;if f ::,,::.-'.,1.i ..i.*t.' i,',:i.j.:.. :: t.. :.i.,t':,, .:i .:ii,:: rrj:i::i;:i": jr r:li. {.ri:.it:-_ - -.j. :rr ::,.i.. vLv,. rv,vt,tlrn.!1.t,tur.rrr.lfr r,"!. :j .' ;.,,ri .,t..",1, l,-, .', by'e"iiA,i'4;,."e:artmii\oa'[i =:,",: .. i' . .1,:, : .',.:;;1-, .;;;ii;i;tf1l,&{

The M Ten-Meter Beam Materials List:2 each junk TV antennas free2 each lVz" x 4" u-bolts$l.80I each 100 pF variable cap.1.00Small nuts. bolts and Misc. 1.20Total:$4.00References:1. Radio Handbook 2lst Edition byWilliam OTTW6SAI2. ARRL Antenna Book. 1974 Edition

GENERAL LAYOUT

GAMMA MATCH DETAILDRIVEN ELEMENT I6 'I, 9 iN

CLAMPS MADE OF

,,.a t00oF vaRtABLE CAPACtTORFigure l. General antenila layout and Gamna nutch detuil. #14 wire connects the SO-239 to thewtriuhle utpacitor- The antenrut resonutes at 28.400 MH;. The SWR ac'ros.s the tcn meter Novice bund(28. I to 28.5) raneesfron 1. l8: I to 1.6: l.March, 1988

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meters. My very meagerjunk box produced onlyone 100 picofarad vari-able capacitor. Back tothe drawing board.The Delta-match mightbe cheap, and the T-match might be a little bitmore efficient, cheap-just one matching-rodone-third the diameter ofthe driven element andone variable capacitor.A 20" scrap of alu-minum close to the rec-ommended diameterserved as the matchingrod. A pipe hanger strapbecame a clamp, and oneof the bakelite blocks be-came a support for thedriven end. The drivenend of the rod was flat-tened and hoies drilled tomount the capacitor. Af-ter final adjustments thecapacitor was coveredwith a plastic vitamin bot-tle. Following the formu-la in the book. the Gam-ma-matching rod wasspaced 1.70 of the lengthof the driven elementfrom the driven element.The Tuning Process

One of the numerouslittle brackets was reamedout to mount an SO-239 tothe boom at its junctionwith the driven element.A short piece of #14 cop-per wire connected thecenter pin of the SO-239to the stator of the capaci-tor. Soldering and clamp-ing the coax directly to theantenna is a possibility,but the convenience oftheconnector is worth the 75cents.After assembling theantenna, a wooden stepladder served as a tempo-rary mount for the tuningprocess. First, the anten-na elerrrent lengths andspacing needed adjust-ment to optimize recep-tion. Ideally, use a low-power transmitter feedinga dipole at the height ofthe antenna being adjust-ed and located severalwavelengths away. other-wise, manually rotate theantenna to peak the signalstrength of operators nearthe target frequency.Then trim the elementsand adjust the spacing forsignal improvement. If

Photo A- The completed beam is in place a few feet below a filo-meter antenna. The end detailof the driven element displays the spacing of the rods which affects the tuning. I % " at the endswork best.

Photo B. Close-up of the Gumma match and the organic rotdtor. The variable capacitor hasbeen covered +vith a plastic bottle and tape.

the reference signalfades, just hunt for anoth-er.More and better testequipment makes trans-mitting adjustments moreprecise, but my Hot-Wa-ter 101 and a homebrewreflectometer servedwell. The Gamma rodclamp and the capacitorwere adjusted for a maxi-mum forward and a mini-mum reflected reading.The antenna was in-stalled at a height of 24feet-only abott1l% of awave length above theground and only 6%above the house. Yes.higher would have beenbetter, but accordins tothe Antenna Book , thewave angle could some-times be as good as 20".Conclusions

Does it work? You bet!Stations barely heard withthe dipole really peak upon the yagi. I get consis-tently better signal reponswith the yagi. too. Somestations think I use an am-plifier. Amplifiers aregreat, but they are morecomplex, more expen-sive, and do not help onreceive. Comparing abeam with an amplifier.the former will definitelyoffer more bang for thebuck.It may not be the mosttechnically sophisticatedantenna around, but forSrl and a few afternoons ofwork with the family thereturns are greater thancan be measured on a sig-nal-strength meter!Want to improve yoursignal in and out'lScrounge around andbuild yourself a beam.Just avoid using two orthree different types ofmetals, and get it up ashigh as possible-mavbebuild your own capacitor.Go ahead and try it. Itcould be the start of some-thing big. lllPeter Bergman can bereached at 902 NE l3thAve. #15, Brainerd MN65401. He is a jack of alltrades whl was attractedto ham radio because ofirs great public sen'icepotential.

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