MAX-GAIN SYSTEMS, INC. announces an expansion of its extensive line of fiberglass rods and tubes to include all-fiberglass quad spreaders-up to 26 feet in length!
Our wide line of fiberglass cubical quad spreader arms allows our customers to select the ideal spreader arm for its intended role: lowest band desired, total number of bands, and the most severe weather conditions likely to be encountered in the customer’s location. You may design your quad with budget in mind, or to be “bulletproof”. In either case, our aim is to give you absolutely the most for your money.
Benefits of fiberglass
MAX-GAIN SYSTEMS’ spreaders – unlike earlier types of sleeved spreaders using smaller diameter, less reliable materials-offer a number of advantages:
- FedEx shippable. Available since the spreaders telescope at 93 inches… saving a great deal over the motor freight charges required for all one piece spreaders.
- Strength. Our design puts the larger diameter (and therefore the greatest strength) where you need it most: at the point of attachment to the boom. The ends of the spreaders are light-allowing flexibility, yet more than strong enough for severe conditions.
- Length. Since each spreader is made from 93 inch sections, there is still up to 26 feet of usable length-even allowing an entire foot of overlap!!! More than enough for a 40M reflector arm.
- Stress point reinforcement. Some of the extra length can be used to reinforce the larger diameter with the smaller, at the point of highest stress: where the clamps secure the arms to the spreader mounting plate. This yields a full 1/4 inch wall thickness for most spreader types!!!
Cubical Quad Antenna Design
See the article below by Steve Root, K0SR in the January/February, 2008 issue of the NCJ which is titled “Design and Construction of a Quad That Will Last.” This article is a great starting point to designing your cubical quad and provides resources to assist in acquiring the needed material. Featuring: Max-Gain Systems, Inc., The Wireman, and Cubex
In order to estimate how far out (measured from the center of the boom) a quad wire of a given length will intersect with a spreader, use this formula:
Take the total wire length of the quad loop in feet (for example, 70.79 ft for a driven element on the 20 meter band) and divide it by 4….(about 17.7 in our example). Then square the result…(about 313.3 in our example). Divide this figure by 2….(about 156.65 for the example) and then take the square root. For our example, this yields the result 12.51, so you know that the wire intersect point will be 12.51 feet out the spreader, measured from the center of the boom.
A far less complex method (with thanks to Ed Niemi, K6EDJ) is to simply take the cosine of one side of the quad loop, (.707 times the length of one side of the quad loop) and measure out the spreader (measure from the center of the boom) to determine the point of wire attachment! The measurement from corner to corner, measuring down one spreader, through the boom, and up the opposite spreader, (wire attachment point to wire attachment point) of each quad loop will be 1.414 times the length of one side of the quad loop.
Minimum spreader lengths required for quad reflector loop at various frequencies*
- 6 meters = 3.7 ft.
- 10 Meters = 6.6 ft.
- 11 meters = 6.9 ft.
- 12 Meters = 7.4 ft.
- 15 Meters = 8.8 ft.
- 17 Meters = 10.2 ft
- 20 Meters = 13.1 ft.
- 30 Meters = 17.9 ft.
- 40 Meters = 25.9 ft.
*(calculated for bottom end of bands)
Buying spreaders to repair a damaged Lightning Bolt quad?? Take a look at this VERY well done page by WB9DLC:
Selecting the right cubical quad spreader
You will want to plan your cubical quad build to withstand the worst weather conditions that it may see in it’s location.
Your quad spreader selection depends on the lowest frequency (band) of the quad design. Example: a 2 element 40 meter quad would require 8x 40 meter spreaders, but these spreaders could also support two elements of higher bands as well.
Your duty type would depend on environmental, weight, and budgetary factors. Heavy duty fiberglass quad spreaders are more robust in their strength, not to mention their ice handling capability, but are a little heavier in weight and slightly more expensive. Choosing the Heavy Duty version is definitely the way to go for a longer lasting quad.
Certain Spreaders offer a “base reinforcement” option. This is to add strength to the area of greatest stress which is at the spider (hubs). Selecting the “base reinforcement” option includes an extra 23 inch long piece of fiberglass for interior reinforcement of the largest tube section of the spreader.
Select Spreaders by Lowest Frequency (Band)
40 meter spreaders
40 meter quad spreaders come in both standard duty and heavy duty configurations. Both allow for the necessary spreader length of 25 feet 10.8 inches, but the heavy duty version uses larger tubing to provide greater stiffness, durability, and force handling capability. Our 40 meter spreaders allow the ability to put the maximum number of bands on your antenna.
30 meter spreaders
30 meter spreaders come in both standard duty and heavy duty configurations. Both allow for the necessary spreader length of 17 feet 10.8 inches, but the heavy duty version uses larger tubing to provide greater stiffness, durability, and force handling capability.
20 meter spreaders
Our 20 meter spreaders come in three “duty” versions. A light duty, standard duty and heavy duty configuration. All allow for the necessary maximum spreader length of 13 feet 1.2 inches. The heavy duty version uses larger tubing to provide greater stiffness, durability, and force handling capability where as the light duty version uses smaller diameter tubing and is a very economical option to get you on the air.
15 meter spreaders
15 meter quad spreaders come in both standard duty and heavy duty configurations. Both allow for the necessary spreader length of 8 feet 9.6 inches, but the heavy duty version uses larger tubing to provide greater stiffness, durability, and force handling capability.
11 meter spreaders
11 meter quad spreaders come in both standard duty and heavy duty configurations. Both allow for the necessary spreader length of 6 feet 10.8 inches, but the heavy duty version uses larger tubing to provide greater stiffness, durability, and force handling capability.
10 meter spreaders
10 meter quad spreaders come in both standard duty and heavy duty configurations. Both allow for the necessary spreader length of 6 feet 7.2 inches, but the heavy duty version uses larger tubing to provide greater stiffness, durability, and force handling capability.
Products to construct your own Cubical Quad Spreaders
Cubical Quad Spreaders
Spreaders are sold individually. For one spreader, buy one. For enough spreaders to make an element, buy four. A 10% quantity discount is available at 10 quantity per Spreader size.
Dacron Rope is non-stretch, UV resistant, and VERY strong (350 pound break strength)
This rope perfect for wire antenna projects. Consider one of our 1000 foot spools if you are going to be using this as rope to help support spreaders.
Best Practices and Information
Wire Attachment Method for Quads – Does Not Require Drilling Spreaders
The following photos illustrate an easy method of making almost indestructible clamps to be used to attach element wires on quad antenna spreaders. This method does not require drilling through the spreaders. Allowing easy and infinite adjustment of the corners of the wire loops, for easy and precise loop centering on the element spreaders. This method cushions and protects the wire elements at the points of greatest stress . the loop corners, and prevents sharp bends which weaken the wire.
These clamps consist of an ALL STAINLESS hose screw-clamp.. (be certain the screw clamp says “All Stainless” or the screw itself will be plated, not stainless, and it will eventually rust), a short length of copper plumbing pipe, and a plastic tube. Very simple, but effective. For the plastic tube, it is best to use a very tough and UV resistant material such as truck air-brake hose (from auto parts store) instead of clear vinyl tube. It will last MUCH longer. Also, spray-paint the plastic tube with flat-black spray paint for additional UV protection.
Connecting Sleeved Fiberglass
(Slotting, Gluing, and Pinning)
There are several satisfactory methods for joining fiberglass tubes together when they are sleeved inside one another (as they are when making a quad spreader.)
Method One: Slotting
One method is to cut a slot in the end of the larger of the two tubes using a hacksaw. The slot should be about 2 inches long, and well centered in the tube. You may then use an all-stainless hose clamp (also called a screw clamp) to fit over the outside of the larger tube and compress the portion with the slot around the smaller tube inside, holding it firmly. This method has the advantage of being easily removable for disassembly if required. A second screw clamp may be used for greater security at the joint.
Method Two: Gluing
A second method is to glue the tubes together. You may use epoxy (the 50/50 type….consistency of syrup….not the “filler” types of epoxy which are the consistency of putty.) Note that epoxy adhesives do not want to bend or flex. They get quite rigid, so if you are using the fiberglass in an application where the joint will be subject to bending, epoxy is NOT the best choice. If you have adequate curing time, adhesives such as “Goop” (or the very similar and cheaper “clear elastomeric caulk” ) are sold in paint departments of many stores with the caulking products. A caulking-gun sized tube is usually around $5, and will do a large number of tubes.
The best adhesive to use is JB-Weld, 2 part epoxy, “Originial Cold Weld Formula”. This adhesive sets in 30 minutes and cures in 4 hours, ready to use in 24 hours. This adhesive comes in two tubes colored red and black (in either 1oz tubes OR the bigger 5oz tubes). When the two are properly mixed together the mixture will turn a medium gray color. Do not apply until you fully mix the adhesive. This adhesive is sold in most hardware stores and also in the paint department. Usually sold in a blister pack that has a red coloration.
A good method of applying all of these adhesives inside tubes is to squirt the adhesive on a dowel or rod of a smaller diameter than the inside of the tube to be glued. Roll the dowel around on the inside of the larger tube, evenly spreading the adhesive on the inside wall. This is easily done from both ends of the tube. As soon as adhesive is spread, slide the smaller tube or rod you wish to secure inside the larger tube and allow to cure. Be sure the tube is not bent when curing, or it will set in that form!
Method Three: Pinning
The third method is by use of a couple of stainless machine screws which go through both tubes. An illustration of this method is below:
For pinning through:
- 1 inch OD Tube, use #6:32 round-head machine screws, 1.25 inches long.
- 1.25 inch OD Tube, use #6:32 round-head machine screws, 1.50 inches long.
- 1.50 inch OD Tube, use #6:32 round-head machine screws, 1.75 inches long.
- 1.75 inch OD Tube, use #6:32 round-head machine screws, 2 inches long.
- 2 inch OD Tube, use #6:32 round-head machine screws, 2.25 inches long.
- 2.25 inch OD Tube, use #6:32 round-head machine screws, 2.50 inches long.
- 2.50 inch OD Tube, use #6:32 round-head machine screws, 2.75 inches long.
When drilling holes for the machine screws to hold sections together, assemble the spreader joint with the exact overlap in place, and drill all the way through both sides at once (taking care to drill straight through the centerline of the tube, perpendicular to its surface.) This method also allows for disassembly if desired. For additional security, apply a little thread lock or glue to the nuts after tightening.
“Pinning” When attaching antennas, rotors, etc… to fiberglass masts or crossbooms, the following precaution is HIGHLY recommended:
Normally, solid rod is used in these applications, because of its great strength, and resistance to crushing when compressed by U-bolts and mounting clamps. Even though it is very strong, the fiberglass is not as hard as the metal clamps or brackets. As a result, as wind and vibration from antenna rotation act on the point where the clamp and fiberglass meet, the vibration will slowly loosen the clamp by “chewing” on the fiberglass.
The remedy for this is to drill a small hole through the mounting bracket, and about half way into the fiberglass rod . Insert into this hole a TIGHT FITTING stainless machine screw. It does not need to be a large diameter, just a very tight fit in both the metal bracket AND the fiberglass rod.
A few drops of a good strong adhesive in the screw threads or in the hole in the fiberglass will also be helpful. An adhesive should be chosen that would hold tightly, but still allow removal of the screw if desired at a later date.
The goal of this procedure is to prevent ANY motion between the clamp and the fiberglass, therefore preventing any loosening over time. It is well worth the effort.
Max-Gain Systems spreaders (in all of our spreader combinations) can have a short 23 inch section inserted into the bottom end of the largest tube. This doubles the wall thickness at the point of greatest stress, and the point where the U-bolts or screw clamps hold the spreader to the spider hub. When installing this internal reinforcement, one of the adhesive methods should always be used. Always try to keep a passageway clear down the center of the tubes for moisture to drain.
Always allow for moisture to drain through any fiberglass spreader. Any water actually trapped in the spreader can freeze, expand as a result and damage the tube. Do not plug either end of the spreaders.
UV Stability and Painting
Any fiberglass, no matter how UV-stabilized, will eventually degrade after prolonged exposure to sunlight. Make your spreaders last many years longer-and decrease their visibility to wife and neighbors-by spray painting them flat black.
First clean/degrease them with a good solvent such as acetone or methyl ethyl ketone…”M.E.K.” (follow their label directions!) Then use a good spray primer-allowing it to cure at least two days. Finally, finish with two good top coats of spray flat black (we like Rustoleum Spray paints for this). This paint treatment is suitable for most any fixed-position use of fiberglass tube or solid rod which will not require sleeving movement between sizes.
NOTE: We do NOT recommend painting our fiberglass push-up masts, or any application in which the fiberglass tubes will be frequently sleeved inside one another.
The inside of the tubes is much more abrasive in nature than the smooth outside, and this abrasive inner surface will quickly scar most paints. Thick or multiple paint coats in sleeving applications will also decrease clearance between the tubes, possibly causing binding. In the case of push-up masts, count on our high percentage of UV stabilizers to provide long useful life.