Binocular choke extras

It’s a tree, like a baobab with pompoms

Ah, thank you, got it. I've used the balun with the additional single wire like in his Fig.14. That hugely improves the balance at the low frequency end, without affecting the HF.

A bit surprising he doesn't have a reference to Guanella. Oh well.

G. Guanella, “Nouveau transformateur d’adaptation pour haute fréquence”, Revue Brown Boveri, September 1944, pp327-329

You may be interested in transformers that extend Guanella's idea, providing impedance ratios other than the squares of integers:

D.A. McClure, “Broadband transmission line transformer family matches a wide range of impedances”, RF Design, February 1994, pp62-66 & May

I admit I never used those in anger though. The parasitic effects of capacitance to cable screens carrying RF voltages and of the residual inductance of the junctions always made me decide to look for other ways.

As I typed it, it was greek lambda over 4. That's usually the mark of transformers with octave bandwidths. My interest was in transformers with multi-decade bandwidths. I used those in bunch-by-bunch trajectory measurement systems in particle accelerators.

Jeroen Belleman

Thanks, that clarifies things. A bit tough to see in the assembly photo, but the center tap on the single turn primary is the shorting bar between the two metal tubes on the same end as the coax inner conductor connections. I suppose the two 1/2 turn primary windings contribute independently to the 4 turn output to provide the stated 1:16 ratio.

Oh, I thought it was an expensive asian drink with floating jelly bubbles of some sort.

Thanks.

My earlier spiel contains a typo. Its last link should be

Danke,