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160M ANTENNA INSTALLATION WB1FTK / KA1SJV ST. AGATHA, MAINE FEBRUARY - JULY 2007 START ESC to exit.

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Presentation on theme: "160M ANTENNA INSTALLATION WB1FTK / KA1SJV ST. AGATHA, MAINE FEBRUARY - JULY 2007 START ESC to exit."— Presentation transcript:

1 160M ANTENNA INSTALLATION WB1FTK / KA1SJV ST. AGATHA, MAINE FEBRUARY - JULY 2007 START ESC to exit

2 -- BACKGROUND -- February 2007 After getting the bug to operate 160m in the winter of 2006, we installed one of the commercially available 160 meter vertical antennas just in time for the 2006 CQ WW 160 contest. This antenna required no guys or radials and claimed to be ground independent. At that time our ground was solidly frozen and, with ~4 of snow down, it was really our only option. The antenna worked when the band was open, but otherwise, not very well. It also had a very poor S/N ratio. In the Fall 2006 we moved and raised the antenna to a better location away from the house / garage and their metal roofs. Performance did improve for the 2007 CQ WW 160 contest, but still, it was nothing to brag about. It had to be replaced. As a side note; We later found that our local ground condition is bad (heavy shale).. this more than likely contributed to some, but not all, of the antennas inefficiency. We looked at other various commercial dipoles and verticals. They too, had questionable efficiencies … they were short, had loading coils, meant to be mounted low or they had unsupported counterpoise arms which are not good in our ice storms etc. NEXT BACK

3 March 2007 the late Winter of 2007 we talked with Dave Bowker, K1FK, in Ft. Kent to get an In the late Winter of 2007 we talked with Dave Bowker, K1FK, in Ft. Kent to get an idea of what he thought might be a good solution. Dave had previously constructed a / 80m vertical at his QTH in Details of the main element construction can be found in either ARRL publication; QST June 04 More Vertical Antenna Classics After a lot of discussion and modeling, Dave designed a modified version for a dedicated 160m 60 vertical antenna with long top loading wires and radials. Our target center frequency was Our target center frequency was MHz with a 2:1 bandwidth of ~80KHz. Early plot indicating Early plot indicating ~30º take-off angle and ~30º take-off angle and good null at the zenith MHz BACK NEXT

4 March 2007 One problem that had to be dealt with during the modeling was the local ground condition, its very poor due to the heavy shale deposits Published data shows our typical local ground conditions as Published data shows our typical local ground conditions as Bad Ground > Conductivity of 1 mS/m Dielectric constant of 3 Where As ( Ref: NEC4WIN ) : Poor Ground > Conductivity of 2 mS/m Dielectric Constant of 12 Poor Ground > Conductivity of 2 mS/m Dielectric Constant of 12 Medium Ground > Conductivity of 5 mS/m Dielectric Constant of 13 Medium Ground > Conductivity of 5 mS/m Dielectric Constant of 13 Good Ground > Conductivity of 6 mS/m Dielectric Constant of 14 Good Ground > Conductivity of 6 mS/m Dielectric Constant of 14 Excellent Ground > Conductivity of 30 mS/m Dielectric Constant of 20 Excellent Ground > Conductivity of 30 mS/m Dielectric Constant of 20 1 Polyethylene pipe used for the coax run Our typical groundcondition BACK NEXT

5 April 2007 The antennas vertical element and four guy posts were constructed from 30 lengths of 5 diameter,.055 wall aluminum irrigation pipe. After cutting the steel couplers from the pipe ends, each resulting section only weighed 30 lbs. The vertical element consists of two 30 sections joined together with a 4 long internal doubler that was riveted in place. The element is guyed at 20, 40 and 60 with the 60 level containing the 55 long top loading wires. May 2007, Installation began After the snow finally melted, we did the layout using a surveyors transit (we have a collection of 25 transits and levels dating from ) to ensure that the guy posts where at 90º, centered on the antenna pier and that the actual guy points were at the same elevation. Each guy point elevation was critical in order to maintain a uniform top loading wire angle, which in our case is 39 ½ º. This gave us a take-off angle of ~30º..... Our final guy point heights were designed to be Our final guy point heights were designed to be.... West 7, North 14 ½, East 9 ½ and the South 8 ½. West 7, North 14 ½, East 9 ½ and the South 8 ½. BACK NEXT

6 THE INITIAL ANTENNA LAYOUT... This was based on our land survey that was done in 2005 It fits perfectly in the available space BACK NEXT

7 GUY POST DESIGN REQUIREMENTS Maintain a uniform top loading Maintain a uniform top loading wire angle of 39 1/2º wire angle of 39 1/2º Tractor cab clearance of 7 under Tractor cab clearance of 7 under the West lower guy line. the West lower guy line. TYPICAL GUY LINE AND TOP LOADING WIRE DETAIL LOADING WIRE DETAIL 14ga Copperweld Top Loading Wire 3/16 Double Braided UV Resistant Dacron guy lines BACK NEXT

8 --- GUY POST INSTALLATION --- After all the guy post locations were double checked against the layout, 8 diameter holes were bored and the forms placed. Each guy post was then set in ~400 lbs of 4000 psi concrete, plumbed and left to cure. Ex: North guy post Ex: East guy post BACK NEXT

9 --- OVERVIEW OF THE COMPLETED GUY POSTS --- West, North and East posts East, South and West posts BACK NEXT

10 After the guy posts were installed, a 1924 Buff & Buff transit was aligned to the antenna pier and all guy point elevations were double checked. This was required before drilling and installing the guy post eyebolts. They had to be in the same plane.. Ex: Checking the South guy point elevation.... Ex: Checking the West guy point elevation.... BACK NEXT

11 Ground preparation for the first 10 of 60 radials began by cutting the grass as low as possible.... Then, using an electric edger with a 7 ½ diameter, serrated steel blade, grooves were cut to a depth of ~1 ¼. Following that, each of the 14ga copper wires were embedded. Natural erosion and grass will eventually fill the grooves... Then, using an electric edger with a 7 ½ diameter, serrated steel blade, grooves were cut to a depth of ~1 ¼. Following that, each of the 14ga copper wires were embedded. Natural erosion and grass will eventually fill the grooves. BACK NEXT

12 K1FK radial bonding clamp made from ¾ copper pipe --- PREPARATION FOR INSTALLING AND BONDING THE RADIALS --- WB1FTK shown cutting the grooves for the radials KA1SJV shown embedding the radials Groove BACK NEXT

13 --- RADIAL PREPARATION AND BONDING TECHNIQUE --- K1FK shown stripping the radials in preparation for silver soldering to the bonding clamp Radial bundle soldered to the bonding clamp and now secured to an 8 ground rod BACK NEXT

14 --- ANTENNA RAISING SEQUENCE --- Were now ready to hand raise the derrick Antenna 30 Derrick BACK NEXT

15 With the derrick fully raised, WB1FTK secured the intermediate South guy points from the derrick to the antenna at the 20 and 40 levels in preparation for the raising. The intermediate guy points will be removed once the antenna is raised. KA1SJVPIC WB1FTKK1FK BACK NEXT

16 The derrick being hand lowered by K1FK, the antenna is now at ~45º. WB1FTK keeping light tension on the top loading wires to prevent them from developing kinks. K1FKWB1FTK KA1SJVPIC BACK NEXT

17 Derrick now fully lowered and the antenna is at 90º With the antenna fully raised, all guy lines are secured to their respective posts so the derrick can be removed. K1FK BACK NEXT

18 --- K1FK BASE INSULATOR --- The lower stud will thread into the antenna pier Once installed on the pier, the antenna will set in the top groove similar to above BACK NEXT

19 --- K1FK RF MATCHING TRANSFORMER --- The bifilar winding on this ferrite rod produces a perfect 25 transmission produces a perfect 25 transmission line required for the low impedance line required for the low impedance 1:4 RF Matching Transformer. 1:4 RF Matching Transformer. Loss at 1.8 MHz, < 0.05 dB Loss at 1.8 MHz, < 0.05 dB BACK NEXT

20 With the raising fixture and derrick now removed and all guys fully secured.. With the raising fixture and derrick now removed and all guys fully secured.. The base insulator, spark gap, ground strap, feed strap, The base insulator, spark gap, ground strap, feed strap, coax and matching transformer box were installed.. coax and matching transformer box were installed.. 3/16 Wide Spark Gap BACK NEXT

21 --- THE COMPLETED ANTENNA THE COMPLETED ANTENNA --- THIS WAS A MAJOR PROJECT; MADE THIS WAS A MAJOR PROJECT; MADE POSSIBLE THROUGH THE EFFORTS OF: POSSIBLE THROUGH THE EFFORTS OF: K1FK, ANTENNA ENGINEERING K1FK, ANTENNA ENGINEERING RF MATCHING TRANSFORMER RF MATCHING TRANSFORMER BASE INSULATOR BASE INSULATOR ( A VERY SPECIAL THANKS ! ) ( A VERY SPECIAL THANKS ! ) KA1SJV, EMBEDDING 3600 OF RADIALS KA1SJV, EMBEDDING 3600 OF RADIALS GUY POST INSTALLATION GUY POST INSTALLATION ELEMENT CONSTRUCTION ELEMENT CONSTRUCTION SITE LAYOUT SITE LAYOUT WB1FTK, GUY POST DESIGNWB1FTK, GUY POST DESIGN GUY POST INSTALLATION CUTTING RADIAL GROOVES GUY POST INSTALLATION CUTTING RADIAL GROOVES ELEMENT CONSTRUCTION ELEMENT CONSTRUCTION SITE LAYOUT SITE LAYOUT IT WAS FUN AND VERY EDUCATIONAL! IT WAS FUN AND VERY EDUCATIONAL! N7GLRPIC WB1FTK ( NICE LIGHTNING ROD ! ) BACK NEXT

22 --- INITIAL TESTING AND FIRST ON AIR RESULTS, JUNE / JULY ANTENNA IMPEDANCE ANTENNA IMPEDANCE Freq = MHz Z = /-j0 Freq = MHz Z = /-j0 Freq = MHz Z = 10 +/-j0 Freq = MHz Z = 10 +/-j0 Freq = MHz Z = 11 +/-j0 Freq = MHz Z = 11 +/-j0 Resonance at MHz SWR 3.9 Resonance at MHz SWR 3.9 SIGNAL STRENGTH AT N7GLR (Compared to 2006, nominal 600W) An increase of ~ + 3 ½ S units (22dB) ( Based on Kenwood TS50 6 dB / S unit ) EQUIPMENT USED FOR IMPEDANCE MEASUREMENTS EQUIPMENT USED FOR IMPEDANCE MEASUREMENTS AEA CIA-HF Analyzer (K1FK) AEA CIA-HF Analyzer (K1FK) PALSTAR ZM30 Digital Antenna Z Bridge (WB1FTK) PALSTAR ZM30 Digital Antenna Z Bridge (WB1FTK) IMPEDANCE MATCHING RESULTS IMPEDANCE MATCHING RESULTS The low impedance 1:4 RF Matching Transformer The low impedance 1:4 RF Matching Transformer lowered the SWR to 1.0 : with a 2:1 bandwidth of ~80 KHz lowered the SWR to 1.0 : with a 2:1 bandwidth of ~80 KHz This also provides ground for static discharge. This also provides ground for static discharge. BACK NEXT

23 SWR PLOT 1.0 : MHz PALSTAR ZM30 Digital Antenna Z Bridge BACK NEXT

24 73WB1FTKKA1SJV73WB1FTKKA1SJV BACK REPEAT ESC to exit


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