I was looking for antenna ideas and ran across the V Beam by  Darrel Koranda KB4XJ web site “The One Element V Beam”

www.hamuniverse.com/1elbeam.html

 

There are others, who used “Ham Sticks” etc. for dipoles, but the cost was not in my budget and home brew that is mostly snap together does not appeal to me.

 

The KB4XJ V Beam has lots of merit. I have seen other V Beam ideas and this one is real simple. I was also looking for another use for Crappie Poles in antennas.

 

The only part that I had to order was the edge trim from McMaster-Carr (www.mcmaster.com per from Phil Silas, “Build Your Own Coils” at www.ad5x.com ).

 

 

 

 

This picture shows the middle of the V Beam looking down one element. This is before painting or adding the loading coil in the center.

 

 

Partial Diagram – not to scale.

1                    PVC Side Out EL

2                    ½” FPT part of PVC Side Out EL – for mounting … with ½” pipe

3                    PVC Conduit Adapter Ύ” SOC – ½” FPT

4                    EMT Connector                

5                    #10-3/4” SS or brass Screws

6                    SS Wing Nut

7                    2 Stainless Steel (SS) Washers – Connect Coax/Loading Coil between these!

8                    5’ section of ½” EMT

9                    EMT connector with pipe thread cut off                 

10                Crappie pole screw cap

11                1” piece of ½” PCV pipe split and glued over EMT

12                Flattened end of EMT with screw to connect the wire element lug

 

Remove the ends from the Crappie Poles. Take the inside sections out and remove the rubber stopper from the bottom of the largest inside section. You will need all the poles open as this is where the wire element will be passed. The crappie pole is just a support for the wire! Some fishing pole designs wire tie or tape the wire to the outside of the pole.

 

(Option: If you use 20’ crappie poles (~$13 each), you can eliminate the 5’ EMT extensions and only use about 1’ to secure the poles to the PVC side out EL. ½” PCV fits 13’ the poles well … you can experiment to see what works best with the 20’ poles.)

 

Remove (sand/scrape) enough from the outside of the ½” PCV Conduit adapters to fit inside the Ύ” sides of the PVC Side Out EL. Screw the EMT Connectors into the PVC Conduit adapters as far as possible. Use primer and glue the adapters into the Side Out EL ensuring that the screws are in line with the ½” FPT side out EL connection.

 

Remove the screws and lock nuts from the 4 EMT connectors. The screws will be replaced with stainless steel screws later. On 2 of these adapters, cut the pipe threads off, leaving the bulge. The bulge will retain the crappie pole cap. Then remove enough material on the inside to allow the adapter to slide over the ½” EMT. Cut a small notch on the inside of the crappie pole threaded cap, just enough to allow it to pass over the female thread boss for the set screw on the EMT connector.

 

Parts in the process of becoming an antenna:

 

1  The cut down EMT connector on the 5’ piece of ½” EMT

2  Unassembled un cut EMT connector

3  PCV to EMT adapter

4  Cut off EMT connector … the cut off threads are on the right

5  EMT connector with nuts and screw installed

6  EMT connector in the shaved down PVC adapter

7  PVC Side Out EL

 

 

 

 

 

 

(Test the fit before you glue anything. Adjust if necessary.) Glue a small section of split ½” PVC pipe to the end of the ½” EMT … this will center the EMT in the crappie pole. Leave about 1” of EMT expose past this PCV bushing for a place to fasten the element.

 

Put the SS screws in the EMT connectors, put the 5’ section of EMT into the center EMT connector and tighten the screw.

Cut 11’ 9” (This needs to be longer … I did not experiment with the length) of the bare copper wire.

 

11’ 9” turns out to be 15.3 MHz in the Right Angle V Beam. Not sure what the correct length is … I moved directly to add a coil for 40 M as that is really the band I wanted.

 

Attach a wire lug to one end and solder. You can pre-drill a small hole in the end of the EMT if needed. Use the SS self tapping screws to secure the wire lug to the EMT.

 

Tuning

 

Insert the wire into the crappie pole and out the far end … let the last piece of pole remain in the pole to allow the wire to stick out for tuning if needed. Tighten the pole cap onto the pole.

 

Connect everything and raise the antenna to at least 10’ from the ground. Check the SWR at the desired frequency (I used 14.25 MHz). Hopefully 1:1. If the frequency for and SWR of 1:1 is lower than the desired frequency trim about Ό” from each wire until the SWR is sufficiently low. If resonant frequency is higher you will have to add more wire. The 11 plus feet that you start with should be too long and thus the F0 should be too low.

 

When the SWR is where you want it, you can move the wire to inside the last pole section and extend all the sections. If you want, use heat shrink tubing at all joints and paint the not black areas … 1 for disguise and 2 for looks. Sometimes a coat of paint making everything match will greatly improve the looks … and in this case should help prevent rust etc.

 

Design considerations

 

The crappie pole has no eyelets to guide fishing line that could get in way or to make this project not look like and antenna.  A fishing pole on the roof might be a bad thing. Hum! I choose to use the 13’ poles and add on … the 20’ pole might be less work … but I was cheap … and the work is no problem. Use what you can get or have and what is within your engineering limitations. I like to plan a bunch, make lots of measurements, drawings and experiment. After you start buying stuff and cutting, grinding etc., you are stuck with some of it … Home Depot won’t take the EMT back in 2 pieces …! You could use telescoping whips on this or the KB4XJ design; accommodate for the difference in length with the EMT. By adjusting these whips you can tune this antenna to almost any frequency below the length of the fully extended whip. E.g. NO COILS for shorter wavelengths.

 

Admission of unattanability

 

I under guessed. The wire needs to be much longer … the folding changed things more than my SWAG covered. The antenna was resonant at about 15.4 MHz. Oops.

 


Add a 40 M coil to the center

 

I mostly work 40 M, but the 20 M antenna seemed like the best place to start and then upgrade since a 64’ long rotating antenna is not practical at my house. I hope that my wife will let me keep the V Beam with 18’ elements.

 

I used a coil made from 14 ga bare copper wire wounds on a 2.5” form that is about 3” long. I used the directions from Phil Silas at www.ad5x.com. I used trial and error to find the lowest SWR using a continuous coil (like the Short 40 dipole). I ended up with a tap at 3 turns from one end and 2 turn from the other.

 

Top - Bottom of the pole sections, Bottom - tops of the pole sections.

 

 

Two views of the side out el and other parts connecting the ½” EMT.

 

 

Detail view of the EMT to Crappie pole connection.

 


Materials

 

Qty      Description                             Vendor            Price    Total

2          13’ Crappie Poles                    Cabela’s           8.00     16.00

4          ½” EMT connector/set screw   Home Depot    0.40     0.80

2          ½” PCV Conduit adapters        Home Depot    0.33     0.66

1          10’ ½” EMT                            Home Depot    2.00     2.00

1          PVC Side Out EL (3/4-1/2-3/4) HD                1.55     1.55

4          Wire Lugs (size as needed)       Junk Box

1          6” ½” Pipe                               Junk Box

1          Mast Clamp                             Junk Box

24’+     #14 or #12 bare copper wire    Junk Box

            (From stripped Romex)

4          Stainless Steel Screws  #10-3/4”         HD       1.02*   1.02

            (Replace Screws in EMT adapters)

2                    SS Wing Nuts  #10                  Home Depot    1.35     1.35

4              SS washers                              Home Depot    0.92*   0.92

            (Only use on base end to connect coax via wire lugs)

2          SS Self Tapping Screws           Junk Box

-           Black Spray Paint                     On Hand

2          1” sections of ½” PVC pipe      Junk Box

1          SO-239 – or as needed            Junk Box

1          2.5” Dia. X 5” coil                    Junk Box

            (Left over from pervious vertical antenna project)

                                                            Total                           $24.30

Miscellaneous

            Mast                                        Solder, soldering iron …

            Rotator/Wire/Controller            Tools (saw, screw drivers, file, pliers)

            Antenna Analyzer                     PVC Glue

            Coax                                        Sand Paper

 

 PVC Side Out EL … 3/4” SOC - ½” FPT - 3/4” SOC (White)

 

 

 

 

PCV Conduit Adapter … ½” SOC Conduit to ½” FPT (Gray)

Any PVC adapter that will go from Ύ” Female PVC to ½” FPT will work.

 

 

 

 Steel 1/2" Unins. EMT Connector, Set Screw

 

 

 

1-1/2"EMT Scr Connector

This kind of Die Cast EMT connector will work for one end of the EMT, but may not work for the pole end … some experimentation might be in order.


 


Last Updated: 2007.08.04 - - © 2000-2007
Comments to: Tom Essary -
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