| High Power Trap Dipole for 40m and
60m This is a 40m and 60m trap dipole which can stand kilowatts! 
The guide line dimensions are for 1.3mm enamel copper wire. Click to enlarge. I will simulate other wires, like plastic insulated wire dimensions later on. 
The 7MHz trap, click to enlarge The trap is made of over killer 100pF/15kV vacuum capacitor in
parallel with an iron powder toroid coil T200-6 with 20 turns of 1.3mm enamel
copper wire. The coil inductance is abt 5.2uH and the nominal parallel resonance
is 7.0MHz.
The antenna wire tension is handled with a polycarbonate piece on top. The wires and the coil are connected to the capacitor with solder lugs and with a stainless steel M8 nut. Note also the shrink tubes in the wires which will soften the tension peaks. The weight of the trap is 300g, which is abt double of the wire weight. That's why the traps are hanging a bit lower depending on the wire tension. Tuning 1. Start on 40 meter. The length of the 40m wire is a bit harder to adjust. Fine tuning can be done by stretching or pushing the coil wire in the toroid to adjust 40m for your desired frequency. 2. On 60 meter adjusts the end part length of the wires for your desired frequency. Start with a bit longer end part wire and fold it tightly back as needed. Very important! All antennas need a choke balun! 
I am using this 1:1 Choke Balun in this trap
dipole. 7 turns PTFE coax in Wurth 742700790. Click to enlarge.
See more information of the choke baluns here www.jumaradio.com/Common-Mode-balun-for-Antennas Basic Part List - 2ea 100pF high Q RF capacitor at least 3kV. Vacuum capacitors are recommended eg this eBay. (Door knob capacitors need enclosures) - 2ea T-200-6 iron powder toroidal core - 1.3mm enamel copper wire - Choke balun parts etc Pros This trap dipole can easily handle more than legal QRO kilowatts. You will get a two band dipole with a performance similar to a full size half wave dipole. Total length is smaller compared to single band dipole. This antenna will reduce the wire hassle in your QTH. There are already so many wires :) Cons The band width is somewhat narrower. Although the weight of the trap is only 300g but you can see that it is hanging lower. Update 2024-05-24 OH7SV Back to OH7SV ham projects |