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Amateur Radio: K3RLL
ANTENNAS


31' UNUN VERTICAL


This "31' Unun Vertical" is the latest all-band portable antenna. While it could certainly be used as the home station antenna with proper mounting, this design is for quick deployment at portable ops such as in public parks. Frequently, even if someone did plant a conveniently located antenna support, (a.k.a., 'tree'), launching a wire antenna into one can be problematic. Public park officials, or at the very least some of the other visitors there, prohibit common antenna launching devices. Trees sometimes sieze our wire antennas and refuse to relinquish them at the end of the day.
Using a telescoping pole as an antenna support provides for rapid deployment in most settings within reach of the available coax feedline to the chosen operating position.
This particular antenna design uses a 31' telescoping pole to accommodate the length of radiator (wire) capable of covering 10 - 80 meters. The shield of the thirty feet or so of coaxial feedline provides the necessary counterpoise.
As shown in the accompanying photographs, a 9:1 Unun is mounted in the weatherproof PVC pipe and cap container shown with either a SO-239 or BNC connector at the bottom for the feedline connection. A side-mounted screw and wing nut serve to feed the antenna wire once unrolled from the surplus fishing reel permanently mounted to the aluminum ground mount.

9:1 UNUN: The Unun itself is created by winding nine turns of trifilar (three wires, color coded if at all possible) wire around a T106-2 toroid core. This is a powdered iron toriod of a #2 mix, 1.06" in diameter. A T130-2 or a FT140-43 toroid could be used. Toroid cores are available from a variety of vendors including www.kitsandparts.com.


GROUND MOUNT: The ground mount, designed by Darryl, AB8GU, consists of a 36" length of aluminum angle with the lower edge ground into a sharp point. This aluminum angle is mounted to the telescoping pole with two 1.50" or 1.75" electrical conduit clamps that have wing nuts at the part where the two conduit clamp arms come together. The user simply loosens the wing nuts to slide the conduit clamps and thus the pointed angle down the telescoping pole so that the lower pointed end is exposed. The wing nuts are then re-tightened to secure the ground mount bracket to the pole in the extended position. Here in Florida, it is a fairly simple matter to wiggle the pointed angle into our sandy ground to anchor the vertical.
To further secure the telescoping pole, one end of three tether lines are permanently secured near the top of the base section of the pole. Each of the three tether lines are stretched out at about a 45 degree angle and secured to the ground with the aluminum tent pegs shown below.


USE: With the antenna wire unwound from the conveniently attached fishing reel, temporarily affixed to the tip of the telescoping pole, the pole is fully extended. The lower end of the antenna wire is then fastened to the 9:1 Unun wing nut. The roll of coax feedline shown in the photos is then connected between the bottom of the 9:1 Unun and the radio, perhaps 25' to 30' away.
With the help of the 9:1 Unun, the internal automatic tuner in my portable transceiver easily tunes the 31' vertical wire on any band from 80 through 10 meters.


A second version of this antenna was constructed using the (now) LDG Electronics S9V31 antenna mast and wire, a similar ground mount and a small Radio Shack project box housing for the Unun.

COST: The telescoping pole is, by far, the most expensive component and may have been $60 or more. The antenna wire cost is negligable as was the flea-market fishing reel. The two conduit clamps were something less than $2 each, the PVC parts about $6, the toroid core was $1 and the aluminum angle was about $6. So, excluding the telescoping pole which could be used as an antenna mast for other portable antenna designs, the total cost for this convenient, all-band portable vertical is about $30.

A similiar commercial version of the 9:1 Unun is offered by Emergency Amateur Radio Club of Honolulu, Hawaii.


The "stealth Vertical", a Hustler 4-BTV that is now painted ALL
flat black, that lives in the garage during daylight hours.

Refurbished/rebuilt SuperAntennas MP-1 for portable operation:

B 'n M Crappie (fishing) pole used to support inverted vee or EFHW

My best antenna - the G5RVjr at 30' in PA


JUMPER DIPOLE:

The first really useful portable antenna constructed for my HW-7 back in the 70s was a 'jumper dipole'. This resonant, multiband antenna is simply a dipole constructed of articulated segments for each band of interest. For my old Heathkit HW-7, I needed 15, 20 and 40 meter coverage. The total length is that of a 40 meter dipole, but with insulators and 'jumpers' at the juncture of 15/20 meters and another set at 20/40 meters.
Essentially, it consists of a pair of jumpers at 11' from each end and another pair 16 feet from each end (leaving a 5' section) and then the remaining 16' or so to the center insulator.


This antenna, depending upon the gauge of wire used, can be easily rolled up on one of those orange $0.99 cord reels available at the large discount stores, among other places


NorCal Doublet: Using 50 feet of light weight speaker wire, twin lead or other readily available double wire, split it down to the 28' point, thus creating two 11 foot 'legs' and a 28' feedline. This balanced mulitband antenna originated from the Northern California QRP Club and with a tuner, covers 40 - 15 meters or more.



ANTENNA SUPPORTS:

Sometimes we run into those portable situations where there are no "naturally occurring antenna supports", sometimes called 'trees'. Here are a couple of options:


Constructed totally of easily obtainable and inexpensive PVC pipe and fittings, this first effort ground support and vertical mast disassembles for easy transit. It requires spikes or tent stakes at the four ends of the square ground mount for stability due to the weight of PVC. I built the mast of 1/2 inch PVC and the base of 3/4 inch PVC, but this could easily be scaled up for additional strength and height. Weight would also go up commensurately, however.
The 20' Crappie (fishing) Pole, as shown above, is a popular antenna support but if the ground is too hard to pound in support stakes, what's a ham to do?

A support option, not available at the time the original PVC Mast and base was first constructed, is the EARC Tripod Mount from Hawaii.

  

This convenient triagular, pre-drilled aluminum bracket is available from the Emmergency Amateur Radio Club of Honolulul Hawaii. Using one 10' piece of 1/2 inch EMT Conduit cut into four equal lengths, and fastened to the triangular bracket with 1/2 inch threaded EMT box connectors, a solid tripod is quickly created that assembles quickly at the portable site and will support a telescoping mast.
I wrapped the vertical center section of EMT with Duct Tape to provide a tight fit for a 3/4" section of PVC that slides over the EMT and inside my 20 foot Crappie telescoping pole.
In addition, an old milk container filled with pebbles dangles from the tripod to provide surprising stability in the wind.


Used as a center support for a doublet or the far end of an EFHW antenna, this tripod is inexpensive, fairly light weight and sturdy.

Looking for a very inexpensive solution to wind up and store your portable wire antennas?
Click here for an Antenna Winder Suggestion


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