Trapped Like a Rat..

I recently did some diddling with traps for a trapped vertical I am deriving and wanted to post some pictures for friends to look at. Personally, I prefer the inductor-and-capacitor type of traps over the coax traps because they are neater (as in cleaner) to build. I make no representations regarding better, more efficient, and so on. I just like hacking off pieces of PVC, wrapping the wire, and paralleling it with a mica cap.

Since I am building a 20m/40m vertical (and may yet add to my growing collections of my 20m/40m dipole antennas), these are built to resonate at around 13.5-14.0 MHz. Unfortunately, the best one (the one with the long- leaded mica cap) resonates at just a pinch under 14.0 MHz so I fear that any antenna made with it will attenuate some part of the 20m signal in the CW band. But, since I am experimenting, I will measure this and see.

I used some small lugs on hand and note that one way to secure the traps to the antenna wire is to drill a hole in the PVC on opposite side of the bolt and nuts used to secure the wire and cap lugs. The wire can be looped through the hole, crimped with zip tie for strain relief, and soldered to the lug. When there's a chance, I will put up some pictures.

For the record, the trap capacitance is 27 pF and the inductance is a shade under 5 uH. Your mileage may vary but, what the hell, a decent hunk of wire, a handful of 27 pF caps (surprisingly cheap on eBay) and wire and -- within days -- you can bloviate with the best of those guys who write the QST articles.

Herewith are the pictures.