HF Antenna Micro-Traps - DIY Build Project

This is the one you've been waiting for - the traps to go with the micro End Fed Halfwave (EFHW) antenna build. Here's how to make them.

These traps will work with my Ultimate Ultralight EFHW (https://youtu.be/s-_LyhdGapM) or just about any QRP end-fed halfwave antenna, and you could even build pairs to use with a dipole.

LINKS:
- LC Resonance Calculator: https://www.omnicalculator.com/physics/resonant-frequency-LC
- Toroid Winding Calculator: http://www.66pacific.com/calculators/toroid-coil-winding-calculator.aspx

You'll certainly need some MATERIALS:
- T37-2 Toroids (my usual): https://amzn.to/3hFsYlj
- T50-2 Toroids (a little more efficient and maybe easier to build): https://amzn.to/2QCkGio
- 28 ga Magnet Wire: https://amzn.to/3b9Isf4
- 39pF 100v Ceramic Capacitor (0603 case recommended): https://www.digikey.com/product-detail/en/kemet/C0603C390J1GACAUTO/399-15862-1-ND/7516362
NOTE: 100v is marginal for 5w. Consider a 500v or 1kv for better durability and/or higher power.
- 500v: https://www.digikey.com/product-detail/en/kemet/C0805C390JCGACTU/399-7155-1-ND/3439396
- 62pF 100v Ceramic Capacitor (0603 case recommended): https://www.digikey.com/product-detail/en/kemet/C0603C620J1GAC7867/399-14992-1-ND/7382541
NOTE: Again, 500v model is needed for 10 or 15w. https://www.digikey.com/product-detail/en/kemet/C0805C680JCRACTU/399-7068-1-ND/3439334
Also, consider a few other capacitors in the 22pF - 100pF range, depending on the traps you'd like to build.
- Perforated Prototype Board: https://amzn.to/35lcvzn
- 5/8" Heat Shrink Tubing: https://amzn.to/3lwwGjt
- 1/4" Heat Shrink Tubing: https://amzn.to/2G9bGzk

And you'll need some TOOLS:
- Dremel (or similar)high-speed rotary tool: https://amzn.to/3gFEkEL
NOTE: I have had my Dremel tool for about 25 years now and it hasn't missed a beat. Based on my personal experience, I would recommend going with the name brand tool.
- Diamond Cutting Wheels: https://amzn.to/2QBRHve
NOTE: I really like these because you can't cut yourself with them, but they cut the perf board and BNC connector brass just fine.
- Soldering Iron (any will do) with a fine tip: https://amzn.to/2GaENlN
NOTE: I've been using this one for about a year with no issues. The heat gun is AWESOME for hot air/solder paste construction. The iron works well for traditional soldering.
- Electronics Tweezer Set: https://amzn.to/2ENy00w

Please share your builds with me when you're done, and tell us about how it works out for you in the comments below.

Thanks!
de K6ARK

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