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I don't think the big sleeve balun I've been using is working so great, what with all of the radio waves bouncing around and off the stucco walls of my balcony. Going to build one of these to use instead. Already got the supplies for it! 👍

#AmateurRadio #HamRadio

#hamradio #amateurradio
in reply to Neil E. Hodges

bazkie 👩🏼‍💻 bitplanes 🎵
bazkie 👩🏼‍💻 bitplanes 🎵
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no idea what it does but that looks so cool! good luck!
in reply to bazkie 👩🏼‍💻 bitplanes 🎵

Comrade Weez
Comrade Weez
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@bazkie the device Nile pictured is an 'unun,' which is a transformer that blocks RF energy on the coax shield on one side of the device from being conducted on to the coax shield on the other side. @tk
@Neil E. Hodges @bazkie 👩🏼‍💻 bitplanes 🎵
in reply to Comrade Weez

bazkie 👩🏼‍💻 bitplanes 🎵
bazkie 👩🏼‍💻 bitplanes 🎵
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@weezmgk thanks, but I have zero knowledge about electrical stuff! so I don't know what RF energy, or coax shields, or transformers are, and what conduction means, etc 🤣

it's okay tho I just enjoy looking at the images!

@Comrade Weez
in reply to Neil E. Hodges

Dietmar aka DL2SBA
Dietmar aka DL2SBA
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What is this black-colored stuff at the base of the N-sockets?
in reply to Dietmar aka DL2SBA

Neil E. Hodges
Neil E. Hodges
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I'm guessing that's just how the N sockets they used look. It's probably paint. (I just have silver ones.)
in reply to Neil E. Hodges

Comrade Weez
Comrade Weez
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@dl2sba it's plastic. Cheap coax connectors for use where you either don't need, don't want or don't care about the coax shield being electrically connected to the cabinet of a device.
@Dietmar aka DL2SBA
in reply to Neil E. Hodges

Comrade Weez
Comrade Weez
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mmm... I think that's an unun. You probably want to make a balun. You don't need a kit, but you can get them. https://www.hfkits.com/manual-for-11-balun-150-watt-for-dipole-antennas/

Manual 1:1 BalUn 150 Watt for dipole antennas - HF kits

HF Kits - Construction manual of the 1:1 BalUn, complete with enclosure, ferrite toroid (FT140-43), PTFE Winding wire and stainless steel fastening material
HF Kits
in reply to Comrade Weez

Comrade Weez
Comrade Weez
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NB: unun = unbalanced to unbalaced (coax to coax) balun = balanced (dipole) to unbalanced feeder (coax)
in reply to Comrade Weez

Neil E. Hodges
Neil E. Hodges
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Good catch. Some folks are really lose with the term "balun", I guess. :P
in reply to Neil E. Hodges

Comrade Weez
Comrade Weez
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yup. I got into a months long fight with an idiot ham radio equipment seller who mislabelled an unun as a balun, which I bought, and for which he refused to accept a return & refund because he damn well sold me a balun... which was marked 'unun' on the unit. He didn't know what an 'unun' was, said I made that up. I still have it, but the bank charged him back and I got the cash.
in reply to Comrade Weez

Neil E. Hodges
Neil E. Hodges
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The dipole I have now has a coax plug on it, so I guess it's time to fire up the soldering iron and make a new one! :P
in reply to Neil E. Hodges

Comrade Weez
Comrade Weez
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yep, just build your toroidal balun in a nice box. NB: The diff between a 150W & a 1kW balun is sore fingers and 16ga wire, but the stiffer version will last forever.
in reply to Neil E. Hodges

VK2TTY he/him
VK2TTY he/him
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[corrected] @tk would that one also be a common mode choke? Blocks ~~DC~~ RF on the shield and the noise (and your own transmissions—ouch!) that’d otherwise get coupled to it. At the antenna feed point, prevents using the shield as a counterpoise. Further down, trims that counterpoise. At the shack wall, said to prevent RF from “entering the shack”… but now I think about it, I’m not 100% on why the position would matter for that? Nor, why I’ve been told to put one at both ends? #HamRadio
#hamradio @Neil E. Hodges
This entry was edited (10 months ago)
in reply to VK2TTY he/him

Comrade Weez
Comrade Weez
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@vk2tty A common mode choke doesn't block DC on the feeder shield, it blocks RF on the shield. Keeps stray RF out of your shack and forces the RF to radiate from the antenna elements instead of from the elements AND the feeder shield. @tk
@Neil E. Hodges @VK2TTY he/him
in reply to Comrade Weez

Comrade Weez
Comrade Weez
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@vk2tty if you need to block DC, you need two windings, one on either side of a core or toroid which don't have DC continuity from one winding to the other.
@VK2TTY he/him
in reply to Comrade Weez

VK2TTY he/him
VK2TTY he/him
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@weezmgk Thanks for setting me straight.

Blocking RF makes sense of the common advice to put one at both ends unless you need the shield as a counterpoise, in which case choke the appropriate length from the antenna feed point.

I'm still trying to nut out W8JI's note here on grounding the shield at ¼λ or ¾λ from the “floating balanced point”. It suggests to me we might learn something by poking the shield with a needle probe on a multimeter. So much to learn! https://www.w8ji.com/common_mode_current.htm

Common mode current

www.w8ji.com
@Comrade Weez
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