I’ve now got two antennas that use traps. One uses real SOTAbeams Pico Traps and the other uses something almost identical. Neither of them have any waterproofing on the traps.
If you use such traps have you waterproofed them and what with? I can always buy some Liquid Electrical Tape to paint on. Or make a simple cover out of plastic material or heatshrink.
The question is whether it is necessary? I operated in freezing fog from Mount Blair GM/ES-035 the other week and after a few hours the traps were covered in hoar frost but the SWR display on the KX2 never moved. I don’t recall it changing when operating in cold mist at the summit. i.e. typical Scottish WX.
For a long time, I used a pair of QRO ‘Isle of Wight’ 40m traps made by the late G3IMX. Though these were cast in resin, the end connections were ‘out in the WX.’ Still have them after 40+ years, still FB.
For QRO use, I have had plenty of success (as in decades of Scottish winters) with the homebrew design shown below. A length of PVC-insulated 2.5mm solid copper wire, and a 5-6kV door-knob capacitor; at one time abundantly available from Ukraine!
The outside is wrapped with PVC tape, but the electrical connections are essentially out ‘in the wind and rain’. Indeed the WX blows down the middle of the coil; but this prevents build-up of moisture which might occur if there were any internal cavities.
As an outer coating, I brush on a layer or two of yacht varnish.
SWR is notably stable. Avoid traps made with RG-58 coax, or similar, doubling-up as the capacitor. These are low-Q and lossy. They won’t melt with 5W, but 100W+ is another matter
I used several diameters of heatshrink. First I shrunk the cable and the trap, then I used another heat shrink to cover the gap between the trap and the cable.
I built a EFHW with individual traps for 15-60m. SWR on 12, 10 and 6m is also less than 2:1, although I never intended to build the antenna for these bands. The project started as a “proof of concept” with the intention of building this antenna “nice and stable” if I was happy with the performance. This was about 5 years ago and I’m still using it wherever I have the space for deploying it.
Very good Jens. Light enough I imagine not to put so much strain on the fishing poles we use. I’ve found the light and cheap 4:1 balun kits that SOTA Beams sell quite effective. They will easily take 10 watts from my KX3.
73 Phil
PS Yes, I also cover the balun boards in heat shrink. Not completely waterproof on the ends where the wires come out but if its that wet during the activation to get into the unit I would already be packing up anyway!
After a lot of experience with assembling contest stations where a belt and braces approach has been taken, I always use self-amalgamating tape to cover my antenna connections. None of my antennas have traps, but I would apply the same principle to them. For a more permanent solution, apply electrical tape or heatshrink over the self-amalgamating as it is sensitive to UV.
I spray my Pico Traps with polyurethane insulation spray. It’s best to mask off a few in. of wire either side of the trap. Time will tell if it’s a good solution. Of course, once they’re sprayed, they can’t be reworked.
73 de OE6FEG
Matt
Ah, 35mm canisters are thin on the ground now. But due to my cruddy Pancreas I have many Diabetic Test Strip containers which are almost the same size. I may try a couple of those.
