Antenna kits created and sold by K4QCD
The Dually
This is two full antennas in one, and you can think of it as two separate builds. I believe it is easier to complete the 49:1 side first and then the 9:1 side. However, you can do either side first.
ATTENTION - This antenna is meant to be use one side at a time with one radio at a time. Only one antenna wire should be connected at a time. Make sure you are connected to the correct BNC for the side you plan to use. This is meant to be used as either the 49:1 OR the 9:1 at one time, not both at the same time.
You can find a great build video from Mike K8MRD by clicking here. Written build instruction are below
49:1 Side
1) Make sure you are looking at the side of the board labeled 49:1. All solder points are through hole and labeled from the top side. Don't let the through holes from the other side confuse you.
2) Take one of the provided toroids and one length of the magnet wire. Fold about 6 or 7 inches of the wire back on itself, and wind that section together. Wind the toroid with the magnet wire as shown. Leave enough wire on each of the three tail ends to work with. Snip the very end fold over of the twisted pair just so it will fit the diameter of the hole on the board.
3) Bend the wire to align with the through holes. The twisted pair goes through the hole labeled shield with the single bottom wire going through the hole labeled center. The top single wire will go through the top hole labeled Ant.
4) With the wires inserted in the through holes snip the wire to just fit through the holes. Strip the enamel off the wire where it goes through the holes so there will be good contact, then solder them into place. (don't judge my solder job. I don't claim to be good at it.)
5) Flip the board back over so you are looking at the 49:1 side and insert the provided capacitor where labeled CAP. From the bottom side solder the capacitor into place and snip the excess wire. -- continue to the 9:1 side.
9:1 Side
1) Make sure you are looking at the side of the board labeled 9:1. All solder points are through hole and labeled from the top side. Don't let the through holes from the other side confuse you
2) Take one of the provided toroids and three lengths of the magnet wire (two of the same color one of different color). Wind the toroid with the magnet wire as shown. Be sure not to cross the wires as you wind. Using the different colors will let you distinguish between the wires.
3) Bend and align the wires to the holes. Insert the wires and trim them so they are just through the board. Strip the enamel off the wire so it will make good contact, and solder them into place. the holes are labeled 1 through 3 on each side. The wire going into hole 1 on the left should be the same wire going into hole 1 on the right and so on. (again I don't claim to be great at soldering.)
Connections
1) Put the BNC connector into place and solder onto the board. Be careful, If you apply too much heat for too long you can melt the internal components of the BNC connector. I use a rubber band to hold them into place until I have one leg soldered. Then do the same for the other BNC connector on the opposite side of the board.
2) Take the provided lock nuts and bolts and bolt them onto the board. Spin on the wing nuts. Technically doesn't matter which way you put them on, but I do it where the wing nut is up towards the side of the board it goes to as you see in the photos. This way the BNC and antenna connections should be on the same side. The counterpoise can be used for either the 9:1 or the 49:1. NOTE - the bolts are 4mm in size so you know for the ring or fork terminals used for your radiating wires and counterpoises.
3) Before applying the heat shrink you can use one or two zip ties to secure the toroids using the 4 hole in the board. Trim (if needed) and apply the heat shrink leaving the top and bottom bolts expose and you're good to go.
NOTES:
There is a lot of information online on use cases for these transformers along with wire lengths and deployment configurations. I don't get into the nitty gritty of that here. Personally I use them mostly in a sloper configuration with the transformer down low, but you could use them in many different ways. It's ham radio have fun and experiment.