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You might talk to VE1JF, Jim Fisher, who has a stack of a C51, C31, and C51, on a 112 foot tower. They are at 37, 75 and 112 feet. I believe he looked into it quite a bit. He also will have some comments on TIC rotators. 73, andy, ae6y ----- Original Message ----- From: "Keith Dutson" <kjdutson@earthlink.net> To: "'Scott Neader KA9FOX'" <ka9fox@QTH.com>; <force12talk@qth.com> Sent: Thursday, August 28, 2003 7:44 AM Subject: RE: [Force 12 Talk] Stacking C36XR + C31XR > Scott, > > I am in the process of putting together a stack at my QTH in Tomball, > Texas. The tower is 150 feet of Rohn 45. There are Phillystran > HPTG6700I (6700lb) guys at four points: 150, 113, 76, 38. This is > overkill since Rohn specifies EHS 1/4 wire (6000lb) for the top guys and > EHS 3/16 (4000lb) for the lower three guys, for 90mph wind loading. If > you use Rohn 45G you should be using three guys with 1/4 at the top and > 3/16 for the lower two. I have three, five foot above ground, 6 inch > metal pipe posts for the ground guy points, at 120 feet from the tower > base. These are each set in about 1.5 yard of concrete. A 100 foot > tower should have guy ground points 90 feet from the base according to > the Rohn catalog. However, be sure to plan the guy design to > accommodate the turning radius of the lower antenna. I have developed > an Excel spreadsheet to calculate the clearance for my antennas. Let me > know if you want a copy to modify for your design. > > On antenna spacing, be sure to consider wavelength for optimum spacing. > I have learned from others that 66 feet is good for 40 meter Yagis and > 33 feet is good for 20 meters. My initial plan was to have two C-4XL's > on the tower. After talking with Tom N6BT and Jay WX0B I decided to add > two C-3's to get 33 feet spacing for 20 meters. So I will have: > C-4XL@152, C-3@119, C-4XL@86 and C-3@53. The guy points on the tower > had to be varied from the Rohn catalog recommendation to provide for > rotation clearance. The recommended maximum vertical guy spacing for > Rohn 45 is 40 feet. > > For antenna rotation I am going with TIC Ringrotors from Array > Solutions. You can order direct from TIC but I hear support is somewhat > lacking from the factory. I am working directly with Jay WX0B to have > his company install the rotors. He is also supplying the StackMatch > boxes for my antennas. Jay has been very helpful with the design of my > system. > > Finally, your feedline length requirements are a major concern in terms > of RF loss. If you have a sufficient budget, go with Andrew LDF5-50A > hardline from the shack to the base of the tower. I am seeing a lot of > surplus cable at hamfests, likely from cell phone companies as they have > replaced 7/8 with 1.5 Heliax over the past few years. My next choice > would be LMR600 from Times Microwave. You can bury both of these > cables, but I would use plastic conduit. Texas Towers carries LMR600 > and the UHF connectors. From there you can use a switch or StackMatch > with RG-8 up to the antennas. My shack is only 30 feet from the tower > so I am using Belden 9913 all the way. > > Good luck. Hope to hear you in upcoming contests. > > Keith Dutson WD5DXL > > -----Original Message----- > From: Scott Neader KA9FOX [mailto:ka9fox@QTH.com] > Sent: Thursday, August 28, 2003 12:34 AM > To: force12talk@qth.com > Subject: [Force 12 Talk] Stacking C36XR + C31XR > > > I'm building a house on a ridge-top location (5 acres). The bad news is > I > have CC&Rs to deal with. Fortunately, I'm approved for a single guyed > 95 > foot Rohn 45/55 tower (plus antennas). I'm starting to think about what > > antennas I would like on it. It will be a single tower station, so > everything will have to be on this tower. I predominately like to do > Domestic (USA) contests such as the Sprints, NAQPs, and Sweepstakes > (although my baby-making activities have curtailed most contesting in > recent years). I also enjoy catching the occasional new band country, > busting the piles, etc., as well as 6m/2m openings. > > So, I'm contemplating a C36XR on top, which will give me 2 ele on 40m, > plus > 20-15-10. For contesting, a second tribander, perhaps a C31XR somewhere > > down the tower might be nice. (perhaps 40 ft spacing, obviously need > some > modelling assistance with that). > > I'd also need to sneak in 6m and 2m horizontal antennas in the mix, plus > > some type of wire antennas for 80/160. > > This is all very preliminary... but what are the group's thoughts > regarding > a C36XR + C31XR stack? How does one rotate the second antenna? TIC > ring? Swinging Gate? The ridge-top location is known to be windy, so I > > may need 3 sets of guys? It may be hard to get a big antenna to fit > down > on the tower? > > Another concern, which can probably be handled with the right feedline, > is > that the tower has to be in the back 1/3 of the property, which puts it > about 275 feet from the shack. With 100 feet up the top, that's a > minimum > of 375 feet of feedline! > > Next November, I will qualify for QCAO (Quarter Century Appliance > Operator) > status, so be easy on me. > > 73 - Scott KA9FOX > > --------------------------------------------------------------- > Scott Neader KA9FOX (608)788-1234 / FAX (608)787-0100 > Free Ham Radio Classified Ads: http://swap.QTH.com > Web Hosting Services: http://www.QTH.com/prices > Domain Name Registrations: http://www.YourCallSign.com > KA9FOX Contesting & DXing Site: http://www.QTH.com/KA9FOX > > > > -------------------------------------------- > Force12Talk mailing list provided as a service by Force 12 Antennas, > Inc. Force12 Web Site: http://www.force12inc.com > > To Submit Message to the List: Force12Talk@qth.com > To unsubscribe and view the Message Archive: see > http://qth.com/force12/list For problems with the list: contact > force12@qth.com > > > > -------------------------------------------- > Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. > Force12 Web Site: http://www.force12inc.com > > To Submit Message to the List: Force12Talk@qth.com > To unsubscribe and view the Message Archive: see http://qth.com/force12/list > For problems with the list: contact force12@qth.com > -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force12 Web Site: http://www.force12inc.com To Submit Message to the List: Force12Talk@qth.com To unsubscribe and view the Message Archive: see http://qth.com/force12/list For problems with the list: contact force12@qth.com |
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