Build your own un-un

[AK9R]

Alan W2AEW recently posted a video of him assembling an HFKits 49:1 un-un. Seeing how its done might help some of you who think bal-uns and un-uns are too difficult to build.

Alan's video:

HFKits 49:1 kit: https://www.hfkits.com/product/end-fed-impedance-transformer-250w-diy-kit/ HFKits is located in England the Netherlands, so you'll have to deal with money conversions and international shipping. This kit is rated for 250 watts.

The kit is available through the ARRL Store. See below for link to the kit at the ARRL Store.

@prcguy suggests a 50 watt version of the 49:1 balun from eBay: 50W 49:1 Balun Shortwave Without Tuning, PET 100W NEW | eBay

 

[vagrant]

I saw that video yesterday and checked the price. With UPS shipping it is about $62 USD to California. The kit is nice, but the parts can be sourced for less and one could probably make several for the same price as the shipped kit. After sourcing enameled wire there will be plenty to build an EFHW for QRP, or higher power with different parts. There is enough wire left to build quite a few for friends or a club project.

That 50W one on eBay is pretty low cost and already built, or save $2 for the kit.

 

[littona]

That video would've come in handy when I was building mine a couple of months ago. The documentation on their web site is sketchy at times. The company is Dutch. I bought directly from them and it wasn't too much of a hassle. I'm still waiting on the 50ft RF cable I ordered from MFJ back in April, however.

 

[AK9R]

The ARRL kit includes the HF Kits un-un and 66 feet of wire for stringing up as your antenna:

End-Fed Half-Wave Antenna Kit

ARRL has partnered with HF Kits to bring you this easy-to-build 4-band antenna kit: an end-fed half-wave (EFHW) antenna. We built it in the ARRL Lab, set it up outside, trimmed the wire for the lowest SWR, and got it on the air. Now it’s your turn!

www.arrl.org

 

[vagrant]

They should include six mix 31 ferrite beads/RF choke to be used on the coax a few feet from the radio. At a minimum they should tell people, since they do not advise about the counterpoise lengths and more.

I built an EFHW using some parts prcguy provided. I made a 49:1 transformer and use 20 meters of wire. The coax acts as the other half of the antenna, so an RF choke is used just a few feet from the radio and not at the feed point.