Building the CaHRTenna Poseidon: A non-resonant vertical antenna powerhouse

Michael, you always make us look good lol! I'm glad you were able to make all the contacts on such a potential bad day. We have found that this antenna also works great for FT8, it is now Ape's favorite antenna. Thank you for the great video and can't wait to see you use it again .

Glad you liked it Michael, thanks for the review 👍

very good video. love the park ! nice video of the park . very nice antenna build . easy to deploy and take down. great POTA and SOTA antenna . love the tune on the bands . we need to take better care of out planet . that why I like POTA so much. so many great parts around the world. keep showing video of the parks like you do. even the history ! love the birds as well. all wild live I love. 73's

Thanks for an excellent review, Michael. Your detailed evaluation on its excellent performance at the end of the video sold me, and I ordered one ! 73, W3WJ.

Wow. That SWR chart was NOT predictive of actual performance. Great video!

Sweet! I made it on your video! Always great watching and learning from your content. Thanks for all you do in the hobby! K4PWI 73

Great review Michael…. I’ve finally broke down and got the Heil BM-17 headset that you have been using in your videos. Heil has a 10% off code that expires on March 28th.

I have been using a switchable 9:1/4:1 UNUN using the same core for about 6 months now, I've had great luck with 58' inverted V and 29.5' wire in vert/sloper and a pair of 17ft counterpoises. I find that the 29.5' works well from 2m (surprisingly easily tunable and good simplex performance) to 40m, 80m is tunable but haven't tested. the 58' wire worked great 80-10. I'm using a small qrp manual tuner with ic705. testing this core in 9:1 with 11 20ga trifillar windings gave me about -0.7db on 20-10m, -0.9db at 40m and -1db at 60-80m and -1.5db on 6m and 160m. (tested in the series s11-s21 with 2 cores)

Great job. Keep up the great work

Thanks again KB9VBR!

Michael, outstanding video as usual! I've been using mine mostly on FT8 for the past couple of weeks, hundreds of DX stations (including Antartica) with it. Ape and I also smoke tested it a bit, ran up the power on my amp to around 250 and did ft8 for an hour or so. Not super scientific, I ran out with a thermal imager every so often to check temps, we had it up to 160C, and it was still rocking.

I have mine on the bench. Plan on putting it together in the near future! 73

Like how you spooled the wire with the bowl and pencil. Thanks for another great video. 73, KF0NNQ.

25ft is a good trade off.. still a 3/16 wave on 40 but not much more than a 3/4 wave on 10. So you avoid too much inefficiency on 40m and avoid creating higher lobes for take off on 10m. It’s a good all bands in one radiator antenna. It’s a compromise but 99.999% of antennas are to some degree. On 17 and 15 it acts very much like an efhw so is less ground radial dependent. It’s like a 5/8 on 12m so produces a good low angle pattern. It has nice gain on 10m. On 20m it’s a 3/8 wave vertical so should give a good match to 50 ohms with a 4:1 unun as feedpoint impedance here is around 200 ohms. On 40m as it’s 75% the length of a quarter wave you should expect it to be around 6dB down but not a massive deal breaker. Thanks for the video Michael 73.

I’m a rather new ham, licensed for about 4 weeks and just got my general yesterday. I have my new radio, the FT-710, and looking for a multi band antenna. Will the built-in tuner in the FT-710 ‘handle” this antenna without the need of an external antenna tuner? If I understood the video correctly it tested out at 3 to 1. I will be predominantly on 10, 20 and 40 meters. Thanks for your content!

How is this antenna different from just stringing an EFHW or EFRW vertically?

I would recommend a good set of flush cutters. I use mine so much I buy them in a 5 pack.

Source for the coax with 1:1 choke you mentioned?

I just built their Apollo EFHW -- my first time building an antenna, first time soldering anything -- but what with one thing and another, I haven't had a chance to USE it yet. I'm looking forward to seeing what I might get with a wire a bit higher in the air than my usual 17' whips. I just don't get anything like the DX you seem to get routinely, and we're not that far away (I'm in the Twin Cities!), so geography is probably not the difference!

Nice review of an interesting antenna. I fully support CAHR and it looks like they've put together a fantastic kit but I can't help but wonder if a budget minded ham might DIY with a LDG RU-4:1Unun for about $30 and wire they already have? I see the core material may differ but how much difference would that make?