The 49:1 Half-Wave End-Fed Transformer Campain is ON!

[gil]

Please share:

https://igg.me/at/radioprepper

Gil.

[caulktel]

Gil,

I like the idea of your campaign. I have a question though, for years I have been building EFHW auto transformers using this method, http://www.zendamateur.com/download/file.php?id=4051 which is a 60:1 transformer. Yours is a 49:1, whats the difference? Mine seem to work very well, would there be a advantage to using a 49:1 over the 60:1? Just curious.

Joel
N6ALT

[caulktel]

Gil,

I don't know if you will be able to read this thread or not, but it's all about EFHW and 49:1 transformers and the like. Some of the people were shouting at each other, but still some good information. https://groups.io/g/BITX20/topic/end_fed_antennas_w_ubitx/23807137?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,23807137

Joel
N6ALT

[gil]

Many of these people have no idea what they're talking about. These transformers do not have high losses. A 240 size core is 90% efficient and a 140 core around 70%. For all practical applications, you'll never hear the difference. What matters is the resonant half wave wire.

Gil.

[caulktel]

Gil,

I agree, most of these groups have a select few people that like to hear themselves talk and are self professed experts. I have been using EFHW wires with 64:1 and 49:1 transformers with great results for 30 plus years. I continue to use them and will keep using them. As far as I'm concerned, I can't tell any difference between using a 49:1 vs a 64:1 transformer either, they both seem to work equally, just slightly different wire lengths. We use what works, including my Mag Loop which people say is a waste of time but mine works great.

Joel
N6ALT

[gil]

Yep, the proof is in the pudding, not the internet :)

Gil.

[M0ORY]

I seem to recall reading somewhere that -43 was a good mix to use for the transformer cores however -52 supposedly performed slightly better but was more expensive. I made my first 49:1 transformer out of a pair of stacked FT140-43 cores and it worked a dream when I tested it on 80m wspr. I decided to get some -52 mix cores. I got a 150-52 and a bag full of 44-52 beads as they were cheap and I thought might be useful for threading over some coax to make a choke. Today I had the idea to make a 49:1 out of a couple of the 44-52 beads stacked. I used 4 beads and the finished transformer measures just 20mm long by 14mm wide. It might not stand up to much power but even if it dissipated a full 5w it's take a while to burn up. I'm going to go out and test it side by side with the 150-52 and 2x140-43 but if it works it'll make a brilliant transformer for prepping when paired with something like the LNR precision Mountain Topper. Actually come to think of it I have some small -43 mix cores too left over from another project so I'll make another out of four of those first and test all four over the next week or so. If they work I'll also try potting them in epoxy in a small container. I think I have an old APS film canister kicking around somewhere which would be ideal. I might be able to 3D print something even smaller though.

[gil]

Hello, very interesting, please post photos! Potting did not work for me, but you might have better luck...

Gil.