5 Band vertical for airstream and others (1970 rev 2015)
(Note... I tried to upload this as a file and it wouldn't... with pics and drawings... email me and I will send you the orginal file with them )
DESIGNED By G.M. AMTHOR WA6CDE (1971)
I got real tired of seeing my design that others claim that they came up with for the Airstream RV antenna mount. I decided that I would again show others what I came up with in 1970's and some of the improvements that now are incorporated in MY original design. (Yes I know that the ARRL published MY design in a article, written by an 8 call person, that had copied mine without permission. I originally wrote the article and showed others at the Airstream Club rally how to make one. I designed this antenna installation and through the years made improvements' to it. I will show all some of the improvements made to the antenna design and continual revisions to it.
A DELUXE RV 5-BAND ANTENNA
This antenna was designed to be mounted on a 31-foot Airstream travel trailer. With minor changes it can be used with any other recreational vehicle (RV).
Perhaps the best feature of this antenna is that it requires no radials or ground system other than the RV itself. (Airstreams are made from good grade of alu)
The installation involves the use of a Hustler 5/6BTV vertical with the normal installation dimensions.
The modified antenna is mounted on a special mast that is hinged near the top to allow it to rest on the RV roof during travel.
HOW TO MAKE ONE
The secret of the neat appearance of this installation is the unusual mast material used to support the antenna. Commonly known as Square tubing, it is often used to make fences, desks, other projects. The size selected is 2 x 2 x 0.125-0.250 in.
The material is an extremely tough steel that resists bending but is very easy to cut, drill and weld. It should be painted when finish to prevent rust and corrosion; it may be painted to match any RV color scheme.
The supporting mast is secured to the rear frame or bumper of the RV by means of bolts but, we prefer the adaption of a angle bracket that would fit into a common 2x2 trailer hitch receiver
(Rev 2: we had 2 welded on the frame which extends to the bumper of the trailer.)
These can be used for other items such as bike mounts, accessories', etc. when not used for the antenna mount.
Here is the typical angle mount for the antenna/car.
Or a second type (Rev 2) of these which can also be adapted for the center section fold over that contains a stop which with modifications by reversal or extension of the tube becomes the center fold over.
Any of these brackets can also be used for the tow vehicle trailer hitch mount also.
Any brackets mounted higher will require a change of dimensions.
TYPICAL ANTENNA MOUNTING
Originally we install the antenna on the curb side of the vehicle to hide the lowered antenna behind the RV awning and provide greater safety to the person raising the antenna. This precaution is primarily for safety when stopping alongside a highway to meet a schedule. (Caution—beware of overhead power lines!) (NOTE: Revision 2-- Mounting the Hustler on the Road side of the trailer keeps it from interfering (tearing) the RV awning)
Mounting the Hustler The 4BTV antenna base is 2 bolts through a 19-inch piece of sq tube that makes up the flop over section above the welded (or bolted) hinge. A single ball lock bolt in the bottom position or two bolts causes the fold over section to become ridged. Be sure to run ground strapping across all joints (see drawing)
• Instead of one long piece of 2x2 and making the hinge fold over on the end it was found that welding the fold over section (to a 6 inch piece, which is the worked hinge part, was easier to build).
• The addition of the fold over bracket on the bumper allows one to fold the antenna back for easier adjustment.
The top-hat spider rods should be installed ridged only on one side of the antenna so as not to poke holes in the top of the trailer. The other sides are made so as to fold back away with longer screws, springs and washers. (See drawing)
No effect on antenna performance will be noted.
Bring the coaxial cable into the trailer at a point close to the antenna. It is recommended that a choke balun wound of 10 turns or other means be used at the base (feed point) of the antenna to keep RF feedback from getting into the trailer. Be sure to use drip loops the point of entry into the RV. Silicone rubber sealant should be used at the outside connector end and at the RV entry hole. A good place to put the Coax is to follow the trailer frame inside the C section. However, it can be placed in support holders on the underside of the trailer also. Great care should be taken to obtain a good ground return from the antenna all the way back to the transceiver.
Heavy duty tinned copper braid, should be used across the mast hinge, the mast-to-RV frame and to bond the frame to the equipment chassis. This is absolutely necessary if the vertical quarter-wave antenna is to work properly.
Antenna Pruning and Tuning The antenna must be carefully tuned to resonance on each band starting with 28 MHz. One can use a antenna analyzer such as the 259 for quick simple tune up. It is a good idea set the tuning for the center of each band. Tuning of the antenna as described will resulted in an SWR of 1.5:1 or lower at resonance on the 3.8, 7.15, 14, and 21-MHz bands.
This system design also provides full band coverage on the 7 through 28-MHz bands with an SWR of less than 2:1. Band coverage on 3.8 MHz is limited to approximately 100 kHz because of the short overall length of the resonator coil and whip. The tip rod is adjustable to enable you to select your favorite 100-kHz band segment.
• Ground radials can be attached to the rear bumper extending out from the back of the trailer for better impedance of the antenna
• One can add the 30 meter portion to the hustler antenna so that it becomes the 6BTV with little or no modification.
• Concerns of the antenna movement when folded over on the roofline of the trailer when under tow can be reduced with the addition of a support at the fold over hinge point and/or providing a spacing away from the trailer body and/or by using some of the Teflon material such as a cutting board. One also then could use a hold down strap at that point so that the antenna won't bounce up or do damage. Access to this spacer/hold down can be achieved with a small ladder or some other means.