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NTMSMicrowave

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Design & Build 23 cm Yagi Using Simple ToolsTools

WA5TKUWes Atchison

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NTMSDL6WU Yagi DesignMicrowave

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• Design Presented in 1982 ArticleDesign Presented in 1982 Article– Published in UKW-Berichte January 1982

IssueIssue– Titled “Extrem Lange Yagi-Antennen”1,2

• Elements Shorted to Boom• Elements Shorted to Boom– Hole in Boom Drilled Smaller Than Element

El t D i I t H l With H– Element Driven Into Hole With Hammer– Cold Welding Element to Boom

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NTMSWA5TKU AntennaMicrowave

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• Built DL6WU 1982 Article Based Antenna in 1986

• Gain Measured at Central States VHF Society M i i S L iMeeting in St. Louis

• Converted All Measurements from Metric to Decimal English UnitsDecimal English Units

• Boom Was Split to Fit in Back of Van• Antenna Installed on Tower For August 1986• Antenna Installed on Tower For August 1986

UHF Contest – Taken Down April 2009 to Repair Broken Boom

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NTMSWA5TKU AntennaMicrowave

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• 13 5 Foot Boom Boom to13.5 Foot Boom– 5/8” Diameter

0 058” Wall

Boom to Mast Plate –

Attached with Hose – 0.058 Wall

Thickness– 3/16” Element

Clamps

– 3/16 Element • Folded Dipole

1/8” B– 1/8” Brass Welding Rod

Folded

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Dipole

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• 3/16” Elements Cold Welded to

Thru Boom Cold WeldWelded to

Boom• NoNo

Elements Lost After 23 Y23 Years

• Boom Joint Gave Way

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Gave Way

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NTMSWA5TKU AntennaMicrowave

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• Folded Dipole pFeed

• Balun - UT141 S i Rid dSemi-Ridged Coax

• N Type Coax UT 141• N Type Coax Connector

• Tuned By

UT-141 Balun

u ed yBending 1st

Director1/8” Brass

Rod

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NTMSElement Cutting JigMicrowave

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g g

• HoldsHolds Element Material3Material

• Adjust LengthLength

• Cut

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NTMSWA5TKU Element Cutting JigMicrowave

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• Modified Jigg• Placed Rod

Holder Back to Back

Holes Misaligned to Better Hold Rod

Back• Used English

ScrewM d E h• Measured Each Length Change With Rule

Adjust Screw• Chamfer Element Ends 45o With File or Sander

Cut Here

Adjust Screw to Length of

Element

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NTMSFolded Dipole Bending JigMicrowave

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p g g

• Use DowelUse Dowel Diameter of Dipole ID3Dipole ID

• Dowel Space to Dipoleto Dipole Length

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NTMSBoom Drill JigMicrowave

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g

• 1x4 & 1x2 8’ Metric & English Scale

– Right Angle Mount

• C Clamp to

English Scale

pDrill Press Bed C Clamp Boom Material to Jig C Clampg

• Use Small Finishing Nail to Pin Boom

1x2 Screwed

to 1x4

C Clamp Boom Material

to 1x2 in 2 Places

to Pin Boom While Sliding Jig on Drill Press Bed

to 1x4

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Press Bed

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p

• VK5DJ Software4

• 41 Directors• Round

Boom• Bonded

Thru Boom• Used

UT141 Semi-Ridged Coax for Balun

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• Calculation• Gain is

Calculated ith E hwith Each

Element• FoldedFolded

Dipole Construction

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p

• Folded Dipole

• All Element S iSpacing From End of Boom

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p

• BalunBalun Construction

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NTMSReferencesMicrowave

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• 1: Gunter Hoch, DL6WU, “Extrem Lange Yagi-, , g gAntennen”, UKW-Berichte 1/1982, pp 3-11.

• 2: Rainer Bertelsmeier, DJ9BV, DUBUS 2/1994, pp.46-52 htt // l t/ k1 dj/dj9b 23 df52, http://www.qsl.net/ok1cdj/dj9bv23.pdf

• 3: “Folded Dipoles for VHF/UHF Yagis”, In Practice, RadCom (RGSB), April 1998,RadCom (RGSB), April 1998, http://www.ifwtech.co.uk/g3sek/diy-yagi/dipoles.htm

• 4: Yagi Calculator by John Drew, VK5DJ,g yhttp://vk5dj.mountgambier.org/Yagi/Yagi.html

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