The Gray-Hoverman antenna final assembly is straightforward once all the parts are made. This is the last of several Instructables covering construction of this antenna that receives UHF stations and, optionally, those in the high end of the VHF band. A list of the other instructables is provided. To see my related Instructables, click on unclesam in the INFO box at right then repeatedly click NEXT to page through them all. I built a single-bay version of the double-bay antenna described in the downloadable color pdf drawing found at this link http://www.user.dccnet.com/jonleblanc/Canada_TV_Stations/Gray-Hoverman/DBGH_VHF_hi_Antenna.pdf. This Instructable is not a plan for building a particular antenna, but the methods I used to build mine, which attaches to a standard length of 1 1/4-inch diameter metal mast, could be applied to the many versions of the G-H antenna. It is up to the builder to determine many of the specific dimensions, which depend on the version being built and on options and personal choices. Note the license information printed on the drawing, which is offered free for private use, but commercial exploitation is prohibited. In the final step I include links within Digitalhome.ca that further describe the antenna.
Step 1: My Other Gray-Hoverman TV Antenna Instuctables
a. How to mark, cut, drill and join plastic pipe and fittings:
b. Make The Active Elements:
Build the assembly jig:
Prepare the copper tubing links:
Assemble the active element:
c. Antenna Plastic Frame Assembly:
d. Reflector Rods:
e. Straighten Copper Wire:
f. Make tophat (alternative to straight) NARODs:
Step 2: Materials and Tools
Plastic antenna framework: see Instructables
Plastic Craft, Framework Assembly
Antenna active elements: see three Instructables
NARODs (optional), 2, # 10 solid copper wire, cut to length to optimize VHF-high station most of interest--see pdf antenna drawing
Reflector rods, six for UHF-only, eight for UHF and VHF-high, see Instructable Reflector Rods
Supports for the two active elements, 5, T-shaped, assembled from marked CPVC pipe and tees, dimensions depending upon the antenna version being built. Drill holes that will accept #6 screws only in the two ends of the support that will be the signal pickoff points for the antenna, drill all the way through, the spacing determined by the antenna drawing. Holes for the others will be drilled in place to fit the elements.
Element and NAROD supports, 8, made from modified 1/2-inch CPVC elbow and with 1/2-inch CPVC pipe cut 3 1/2 inches long, see Instructables Plastic Craft
NAROD end supports, 4, 1/2-inch CPVC pipe cut to 3 1/2 inches long, one quarter-inch diameter hole drilled through one end, see Instructables Plastic Craft
Pipe cap, 4, 1/2-inch CPVC, hole drilled into only one side, to pass # 10 wire
Brass screws, 16, 3/8-inch long, #6, nuts and bronze lock washers
Brass screws, 2, 1-inch long, #6, 6 nuts and 3 bronze lock washers
Nutdriver or adjustable wrench
Primer for cementing PVC plastic plumbing pipe and fittings
All-in-one cement for PVC and CPVC plastic plumbing pipe and fittings
Q-tips for applying plastic primer and cement
PVC tee, 2, 1-inch by 1-1/4 inch. Temporarily slipped over the ends of the lower of the two crosswise horizontal element and NAROD support tubes, to form feet that, along with the bottom bell of the lower 1-inch PVC cross fitting, can support the antenna upright on a workbench as it is being assembled.
Step 3: Insert NAROD Supports and the NARODs
Slide, but do not glue, the two 1-inch by 1-1/4-inch tees on the ends of the lower of the crosswise element and NAROD support tubes that, along with the bottom of the PVC cross fitting, form three feet that allow sitting the antenna framework upright on a workbench.
Insert NAROD supports, and the NAROD end supports, into their holes in the crosswise horizontal tubes of the antenna plastic frame, but do not glue them at this time. See Plastic Craft for how to glue them in place when the time comes.
Slide in the NARODs and install the drilled pipe caps to capture them on the ends of the NAROD end supports, taking care no to bend the NARODs. (This arrangement is obviously overkill for supporting straight NARODs, however I wanted to be able to also support the optional "tophat" NARODs, for experiments. See Plastic Crafts Instructable for details).
Step 4: Install Element Supports
Insert the five element supports into the antenna's spine, making sure the one that will be the signal pickoff is the middle one. Measure to position them so that the installed active elements will be the specified distance from the centerline of the reflectors. Cut a spacer that will fit between the lower edge of the bell of the CPVC tee to the surface of the antenna's spine tube, to set that specified distance during cementing. Set up the antenna's frame on a bench so that a carpenter's square can be used to ensure that the element supports will be installed perpendicular to the antenna's spine tube. Using the spacer and square, carefully cement each element support in place.
Step 5: Install Active Elements
Attach each active element to the antenna, at the signal pickoff point, using a one-inch brass screw, passed all the way through the element support, with one brass nut inside the pipe and another, with bronze lock washer, on the outside. Snug up the inside brass nut so it will back up the outside nut. A second brass nut will be added to the end of each brass screw to secure a wire from the balun that converts the antenna's 300 ohm output to a 75 ohm coaxial cable. Drill holes for #6 3/8-inch brass screws in the ends of the remaining element supports, and in the flats of the NAROD supports, gently bending the elements to line up with the supports if necessary. Attach the elements to just the element support tees, place the heads of screws inside the CPVC pipes, the lock washers and nuts outside.
A second attachment method that I used in a more recent antenna, is to use copper pop rivets and copper backup washers, see the composite photo. The pop rivets were ordered from Best Materials website, box of 100. The copper washers were found at TruValue hardware store, sold as "burrs" for use with conventional copper rivets used in leatherworking. I pre-curved the washers by hammering them around a steel rod. The signal pickoff included brass nuts soldered to the appropriate corners of the active elements during their assambly. Brass screws, inserted from the backside, secure those two corners to the frame. The wire lugs from the balun are connected using bronze lock washers and a second brass nut.
Step 6: Cement the NAROD Supports
Adjust the NAROD supports so that all parts of the active elements will lie in the plane defined by the glued-in element supports, and adjust the end NAROD supports so that the NARODS will be straight. Remove the CPVC caps and the NARODS and mark all the NAROD supports for their depth and rotational position. Cement the NAROD supports in those positions and re-install the NARODs. Cement the four CPVC caps to gently confine the NARODS. Use brass screws and nuts, and bronze lock washers, to fasten the ends of the active elements to the NAROD supports, with the screw heads inside the CPVC pipe.
Step 7: Insert the Reflector Rods
The 6 (or 8 if NARODs are used) reflector rods are installed within 5-inch lengths of 1/2-inch CPVC pipe, their lengths, and the gap between their ends, according to the antenna drawing. The CPVC pipes are given marks that make it possible to show that they are centered within the antenna's spine while they are being cemented. Cement the rods in place, making sure that the different lengths are in the correct locations. PEX is easily damaged by sunlight. If the antenna is to be mounted outdoors, drill a 3/8-inch diameter hole through the centers of 1/2-inch CPVC pipe caps and glue one to each end of each reflector CPVC pipe once the reflectors are installed in the antenna.
Step 8: Attach Antenna to Mast
SAFETY NOTE: Just because you are able to build your own television antenna does not mean that you should install it yourself. There are many risks for property damage, personal injury and death. Seek a professional installer. Mark and drill two holes through the metal mast to accept 1/4-inch bolts. Elongate the holes in the lower of the two PVC crosses, to allow for movement of the plastic antenna with temperature changes. Attach the antenna to the mast using 1/4-inch bolts and washers and nylon locking nuts. The lower of the two bolts and nuts should be tightened only snugly, to allow the plastic to move. Connect the wires of a balun to the signal pickoff point, secure the balun to the antenna's frame, and run a coaxial wire to a mast-mounted preamplifier or directly to the television.
Step 9: Antenna Information Links
1. Introduction to the Gray-Hoverman antenna
2. Antenna Research and Development Forum
3. Link to the license: