# Tag Info

## Hot answers tagged choke-balun

6

If you do it right, the bead(s) shouldn't get hot at all, and shouldn't add much loss. The impedance of the bead(s) should be about 10 x the impedance of the dipole. The current on the feedline with no balun might be about half the antenna current. With the beads on it it'll be less than 1/10 of the curent, or 1/100 of the power. Small beads (3.5 mm inside, ...

5

A choked end-fed antenna is (or acts just like) a highly off-center fed dipole, where the length of any stub between the common mode choke and the unun/transformer/feedpoint sets the off center ratio and thus the impedance at the antenna feed point. Your current 1 foot stub is less than 1% of the antenna, whereas a few percent is usually recommended, that ...

2

Different beats have different attenuation at different frequencies. My gut tells me you want at least 6 dB, preferably more. Guys seem to wind their own inductors as RF chokes but not sure how much attenuation at the desired frequencies.

2

Is it sufficient to construct two 1:1 common mode chokes ... then wire them together as described in the previous paragraph? It is nearly as simple as that. Here's a wiring diagram: In a perfect world, the transmission line wound around each core would have a characteristic impedance of $\sqrt{200*50}$=100-$\Omega$. Books on this subject by Sevick and the ...

1

The very best source of information that you'll find about making common-mode chokes is available at Jim Brown, K9YC's site http://k9yc.com/publish.htm. Download his PDF http://k9yc.com/RFI-Ham.pdf. RFI, Ferrites, and Common Mode Chokes For Hams Most recent update April 2019. This tutorial is directed specifically to RFI in ham radio applications. It ...

1

You build a few and measure them with a vector impedance meter.

Only top voted, non community-wiki answers of a minimum length are eligible