20–40–80 Meter Loaded Multiband HF Dipole Antenna

20–40–80 Meter Loaded Multiband HF Dipole Antenna: 20–40–80 meter loaded multiband HF dipole antenna design using loading coils and a 1:1 balun. A simple, space-saving HF antenna for amateur radio operators.

4:1 UN-UN Transformer for End-Fed Antennas

4:1 UN-UN Transformer for End-Fed Antennas: Learn how to build a 4:1 UN-UN transformer Construction and Working - using a T200-2 toroid for end-fed and long wire HF antennas with clear wiring explanation.

A 4:1 UN-UN (Unbalanced-to-Unbalanced) transformer is a versatile impedance-matching device used in many different antenna systems, not just end-fed wires. The diagram above shows a classic broadband design using a T200-2 toroidal core with bifilar winding, suitable for a wide range of HF antenna applications.

9:1 UN-UN Long Wire Transformer for HF Antennas

9:1 UN-UN Long Wire Transformer for HF Antennas: A detailed guide to the 9:1 UN-UN long wire transformer, explaining its design, connections, grounding, and HF antenna performance.

Most "random wire" antennas aren't actually random—they’re high-impedance headaches. If you’ve ever struggled to get your internal tuner to "bite" on 40m or 80m, you need a 9:1 Unun.

VU3DXR just dropped a deep-dive guide on this essential transformer. It’s not just a wiring diagram; it’s a masterclass in:

• The "Why": How to turn $450\Omega$ into a radio-friendly $50\Omega$.

• The Build: Winding a T-200-2 core for 400W of power handling.

• The Reality Check: A look at actual efficiency losses (and where this antenna shines).

If you do POTA, SOTA, or just love a "stealth" backyard wire, this is a must-read.

🔗 Build yours here: https://vu3dxr.in/91-un-un-long-wire-transformer-for-hf-antennas/

#HamRadio #DIYAntenna #9to1Unun #HomebrewRadio #POTA #SOTA #RadioGeek

5/4 Wave VHF Antenna for 145 MHz Using 450-Ohm Ladder Line

5/4 Wave VHF Antenna for 145 MHz Using 450-Ohm Ladder Line: High-performance 5/4 wave VHF antenna for 145 MHz using 450-ohm ladder line. Simple construction, good gain, ideal for 2-meter FM and repeater work.