sceiv

More documents

Recommendations

Info

planned to use. This top shelf is now their standard design. At the time of my order, Heights could not provide a sufficiently heavy-duty thrust bearing, so I obtained a Rohn TB3 from a dealer and sent it to Heights for their top shelf drilling. Heights can now supply several very nice thrust bearings. Incidentally, thrust b earing eagle-eyes will note four extra bolts on this bearing. These are temporarily inserted as my own modification to prevent antenna rotation while performing maintenance on the rotor; thrust bearings do a wonderful job of turning in the wind when you do not have the mast clamped in the rotor. When you specify the top shelf drilling to Heights and are planning to use a thrust bearing with a 2' mast, I recommend having them drill the top shelf hole 2-1/4' in diameter to allow for alignment and to let the thrust bearing decide the mast center above the rotor. Heights was very cooperative and responsive to my needs for both the top shelf and a rotor shelf that needed non-standard holes. Of course, the hardware is available in optional stainless steel, including the U-bolts for the rotor shelf. Making the Concrete Base If you've never done a self-supporting tower before, you are in for a big surprise when it comes to preparing the concrete base. The base provides all the strength for a self-supporting tower, and it must be done right. For my tower, Heights recommended at least a hole 5' x 5' x 5', and needing 4.6 cubic yards of concrete. I usually do things a bit conservatively, and my base hole was bigger: I poured seven cu bic yards . After heari ng the ou tlandish quotes from several local concrete contractors, I went ahead and did the entire project myself at about half the cost. Digging the hole takes a lot of work when using a shovel and wheelbarrow, so don't rush yourself. After the hole is ready for swimmers, a reinforcing steel bar cage is needed. I've never seen anything harder to cut than those bars! Carbide hacksaw blades bounce olf alloy steel bars, so have several blades ready. Keep the rebar at leasl several inches away from the tower leqs to keep lightning from fracturing the base and then dropping your tower. I did not think I could do the job myself at first, but taking things carefully one at a time without rushing did finally result in a level, framed form ready for pouring. I do recommend buy ing th e special frami ng nails for your lumber forms, alo ng with the fram ing stakes from the local hardware store. The tower will be level if you prepare the base legs with the first tower section attached, and temporarily guy this section. Guying an 8' tower may sound silly, but the last thing you want is tor those seven yards of wet, heavy new concrete to move the legs or tower out of alignment when the co ncrete is being poured into the hole. Photo D shows the formed base ready to pour the concrete. Note that you will have to shore up the first tower section with some lumber to keep the base legs at the proper height. I recommend using a 1" x 2' piece atop each form top and below the shoring lumber to allow access to the freshly poured concrete when you want to finish the top concrete surface. Proper grounding of the towe r is done by running #4 gauge solid copper wire from each leg to three ground rods 8' long and 5/8" thick about a foot out from the concrete, then connecting each ground rod to each other and to the shack ground. The tower legs needed larger ground ctamps than the local hardware store could supply, but I found that the Polyphasor Model J-2 clamps could fit easily. Be sure to make no sharp bends in any ground wire; lightning follows a straight line and does not like curves. I definitely do not advise skimping on materials here; your grounding system is vital to the health of the tower, antennas, radios, and your house. Table One Photo B. Hinged base. Final Construction Now that you've paid lor the tower, dug the hole, paid for the concrete, installed the ground system and rested-you can build the tower. I did it section by section instead of hinging the tower up from the ground. My biggest shock came when I went to use my trusty Rohn gin pole. Guess what? The Heights tower tubular legs are a lot bigger than either Rohn 25 or 45 tower legs, and my gin pole clamp would not fit. Here's where the low weig ht came in very handy. My-1 3-year-old son (N8QER) and I simply pulled each section up by hand with a rope, then planted the new section on the one below. Even the biggest 30" sections weighed only 45 pounds, compared to a higher steel tower section. Also, the 8' section length was much easier to handle than a 10' section would have been. Of course, the use of a quality safety bert by each tower worker is absolutely necessary. By the way, don't underestimate the amount 01 Continued on page 61 Face Width 35' 30' 26' ee- te- 14' 11 ' Section Weight: 631bs. 45 1bs. 36lbs. 301 00. 21 Ibs. 14 1bs. 11 Ibs. Leg Diameter: 1.708' 1.625 1.5625 1.500 1.3125 1.0625 1.062 5 Leg Ihickness: 0.204' 0.162 0.1 3t 0.100 0.114 0.0962 0,0962 z-erece thickness: ~S ' ~S ' 9/16' 112' 7/16' 31S' 31S' solid solid solid solid solid solid solid Photo C. Top plate. 44 73 Amateur Radio Today- June, 1992 Photo D. Formed base.
Packet + AMTOR = PACTORll PACfOR is a new ARO rll
Page 1 and 2: JUNE 1992 ISSUE #381 USA $2.95 CAN
Page 3 and 4: ONG LE~ Greatly I Is" AMlSSB Signal
Page 5 and 6: THETEAM PUBLISHERIEDITOR Wayne Gree
Page 7: their PC to discover the "ell' visu
Page 10 and 11: LETTERS Dave KD8VI, Lakewood OH I j
Page 12 and 13: Number 4 onyourFeedbeclI CIII'd 8,0
Page 14 and 15: inary address is input to the devic
Page 16 and 17: make it easier to remove, you can m
Page 18 and 19: !'Unbet' 5 on yovr FeedbKk card VE3
Page 20 and 21: Figure 2. The wire beam for /5 and
Page 22 and 23: Number . on r- F..ll'Mc~ ~ Touch-To
Page 24 and 25: Pin 17 is the GT (guard time) contr
Page 26 and 27: output and charged up C I). If the
Page 28 and 29: Number 7 on your Feedback e.rd Buil
Page 30 and 31: •• ,. ,.,..,. " " .. :.~'" ,.-
Page 32 and 33: help reduce the " thump" problem. F
Page 34 and 35: You may elect to tinker with the in
Page 36 and 37: VE3CYC's Wire Beam Colltitlued/rom
Page 38 and 39: G S.',"m,,, ,.. ,""", , " Ol 'us,
Page 40 and 41: . ICOM'" R7000 SWEEl'lNG : 1300 CHA
Page 42 and 43: 73 Review by Bill Brown WB8ELK Numb
Page 44 and 45: 73 Review by Mike Baker WSCM The He
Page 48 and 49: HAMSATS Number 10 on your Feedback
Page 50 and 51: y Bill Clarke WA4BLC ELNEC Version
Page 52 and 53: _ «r • .,. .. "" lIea. .....- I"
Page 54 and 55: SANELLI TECHNOLOGY Sanelli Technolo
Page 56 and 57: Arv Number 13 on your Feedback card
Page 58 and 59: .. . - ' .,. "" . ', , -------,-"-
Page 60 and 61: SPECIAL EVENT;,m..",,"",,,..db,,k,,
Page 62 and 63: VE eeeme. Vendors need to reserve s
Page 64 and 65: QRP Number 16 on your Feedback card
Page 66 and 67: ABOVE & BE"YOND~F-- k ~" C. L Hough
Page 68 and 69: 73 INTERNATIONAL Numbet 19 011 y(U'
Page 70 and 71: TALK WITH THE KNOWLEDGEABLE PEOPLE
Page 72 and 73: ASKKABOOM MichaelJ. Geier KBfUM do
Page 74 and 75: Natural Voice Playback Board Datavu
Page 76 and 77: Joe Moel/, PE., KOOV PO. Box 2508 F
Page 78 and 79: NEVER SAY DIE Continu8(/ from page
Page 80 and 81: RTTY LOOP Marc I. Leavey, M.D., WAJ
Page 82 and 83: Carole Perry WB2MGP Madia Mentors.
Page 84 and 85: BARTER Tum your old ham and compeer
Page 86 and 87: PROPAGATiiiN'''....''''~ FCC Enforc
Page 88 and 89: WNlOI Ellel'Yday Electronics Dl tl
Page 90 and 91: YAESU FT-1000 FT-912R FT·747GX FT
Page 92: • 100 Watts on all nine Amateur b

sceiv

Create successful ePaper yourself

Delete template?

Save as template?