HY GAIN AV 640 ANTENNA

User Manual: Pdf HY-GAIN--AV-640-ANTENNA

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Hy
-
Gain AV640 (Patriot) Antenna and Guests
(Updated06November2007)
Ihopetohavelinkstolargerphotossoon
TheAV640likeallmulti-bandantennas,orallantennasforthatmatter,isacollectionofcompromises.
Astherearenotrapstheverticalissurprisinglywidebandoneachofthebandsitcovers(40through6-
metersincludingallthenewWARCbands.)It'sabout200KHzoratadmoreon40whilegivingfull
bandcoverageontheothers.Theantennaisdesignedtooperatewithoutaradialsystem,butitdoes
haveasmallcounterpoiseatthebase.Therecommendationistokeepthiscounterpoiseatleast5feet
awayfrommetalobjectssuchasrainguttersandotherantennas.Onenote,althoughtheaddssaythe
antennaisratedforthefulllegallimitof1500wattsithasalimitof300wattson6-meters.
Assemblyisrelativelystraightforwardwithagoodsetofdirections.Howevertherearealotofpartsso
theassemblyisnota5minutejob.Layoutthepartsinordertomakesuretheyareallthere,followthe
directionsstep-by-stepandexpectacoupleofhoursfortheassembly.

Tuneupwill,orshouldberelativelycloseusingtheirfiguresandeachbandcanbetunedindividually
withoutaffectingthetuningontheotherbands.40metersissetbyadjustingthelengthofthetopmost
tubepiece,oroveralllengthoftheantenna.Thisletmeeasilysetthe40meterbandtofavortheCW
portion,yetoperateinthebottomofthevoicesectionwithabitover200KHzofbandwidthlessthana
2:1SWR.20and15aresetbytrimmingthelengthoftheappropriate"tophats"whilesettingtheother
bandsforthecenter(byadjustingthestublengths)gavefullbandoperation.IftheAV640isplacedon
a10'masttocheck,theresonantfrequenciesandminimumSWRforeachbandshouldbeverycloseto
 
Tophats and loading coilsMatching network and base of
stubsBase of stubs
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whatyougetwhentheantennaismountedonatower.Ontheotherhand,tryingtotuneitina
horizontalpositionislikelytogivesomemisleadingnumbers.
Performance:IhavetheAV-640installedona40foottowerattheWestendofmyshop.Icanonlygive
subjectivefiguresasIcouldnotswitchbackandforthbetweenantennas.Allcomparisonswereagainst
thestationinthehousewithslopingdipoleson40withthetopendsat90feet,atri-bandbean(TH-5)
on20,15,and10at100feet,anda7LYagion15at115feet.Notexactlyafaircomparison.However
theAV640hasworkedwellwithafairamountofDXon40.On6-metersI'veworkedtheEast,West,
andGulfcoasts.Thatistosayitworkedwellundertheconditionsatthetime,notincomparisontoany
otherantennas.
SincethiswasfirstwrittenI'vemovedthefullstationtotheshop.Thishasallowedmetoswitchfromthe
AV640to40meter,centerfed,halfwaveslopingdipoles.AttimestheAV60maybeasmuchas2S-
unitsstrongerandatothertimesitisweakerwhichprettymuchshowsthepolarizationdiversityand
angleofradiationdifferencesatanyonemoment.
 
Two views of the AV-640 and tower
HistoryandGuests:
Ihadbeenmakingafewcontactson40,butusedtherigintheshoptomostlymonitorW1AWcode
practicepriortothissummer.AlthoughtheSWRon6aswellas40seemedtobeclosetonormalthe
otherbandshadchangedfrequencyandtheminimumSWRhadgonefrom1.1:1uptoaround1.5or1.7
to1.Thiscalledforacloserinspectionwhichrequiredloweringtheantenna.Thetowerbaseishinged
sowiththeaidofonehamontheshoproofwitharopeandacoupleonthegroundwhileIpulledon
oneofthenylonguystotheAV-640tokeepitoutofthetreeswelowereditontoacoupleof
sawhorses.(Notetoself:addraisingfixtureorfoldovermast).
OutwardlyIonlyfoundoneinsulator/spacerforatuningstubbrokenwhichshouldnothaveaffected
theoperationoftheantenna.Thenextstepwastoopenthematchingnetwork.Theinsidewaspacked
with"cooked"Waspsandnests.
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Note the pile of Wasps and "Wasp Goo" over the coax connector on the right.
 
The matching network after cleaning and the broken spacer with replacements in the works.
Idisassembledthematchingnetworkandcleaneditthoroughly.Thebrokenspacerwasreplacedwitha
pieceofLexan(TM)andthetoploadingcoilshadtheconnectionscleanedandweatherproofed.
NOTEthespacershouldbealoosefitonthestub.TheAV640isflexible.IftheLexanisatightfit,it
willgrabthestubwhentheantennaislaiddown,bendingthestubandstubattachpoint.
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 
The new Lexan (TM) spacer (left) and the weatherproofed connection for the top loading (right)
 
Flooded Heat shrink tubing used to weatherproof the AV-
640 and TV antenna connections. Cable
grounding at the tower base on the right.
AfterreassemblytheantennawasmountedonatemporarymastandtheMFJanalyzerusedtocheck
resonance,impedance,andbandwidth.
AtthispointIplayed"musicaltowersections"byusingthebest5sectionsfromtwoAluminumtowers
toget40feet,mountedtheAV-640onthetower,andraisedthetowerbackintopositionattheendof
theshop.Raising40feetoftowerwitha25footverticalontopwouldn'thavebeensobadifthetwobig
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treestotheNorthWestweren'tthere.(Onecanbeseeninthetopphotoonthispage).Fortunatelythe
AV640isabitflexibleandtheguylinesprovidedthemeanstospringtheantennafarenoughtothe
Southtomissthetopbrancheswhilethreeotherhamspushedthetowerupintoposition.Theantenna
workedwellforabouttwoweeksandthenwentbacktothesameproblemspreviouslyexperienced,but
withouttheWasps.

SinceItypedtheabovetheantennahasgivenupagain.Iassumeit'saproblemwiththebottom
connectoronthematchingnetworkandIshouldhavechangedthatwhentheantennawasdown.
Addendum:Thebottomconnectorwasbad.IreplaceditwithanewN-typeandtheantennaisbackin
operation.

I'mcurrentlyworkingonthebigantennassoitmaybeawhilebeforeIgetbacktotheAV-640,butit
sureisahandyantennafortheshop.
Onemoretime...TheSWRwentupandtheresonantfrequencyforeachbandshifteddown.Apparently
anearbylightningstriketookouttheprotectivechokeacrosstheoutputofthematchingnetwork.The
chokeisclearlyvisibleatthetopofthematchingnetworkshowninthelowerofthetwophotosofthe
matchingnetwork.AtHyGain'ssuggestionIclippedthechokeoutandallreadingswentbacktonormal.
The says you are caller BacktoRogerHalstead'sHomepage
If you have comments or suggestions on Content or spelling, (Proof readers welcome) email me at
Roger Halstead

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