On 28/08/2012 19:29, Eddy Swynar wrote:
> I am thinking of incorporating a homebrewed 4:1 balun as part of a transmatch
> that I have here, which was designed to feed coaxial cable-fed antennas
> only...
>
> Is there really & truly such a thing as an air core 4:1 balun that will cover
> the entire spectrum from 1.8- to 29.7-MHz...? I've looked & I've repeatedly
> searched on the internet, but can not quite come up with such an animal.
> Maybe the frequency range of such a beast is far too great for any practical
> design...
>
> Anyone have any leads in this regard...?
I've not come across anything that would cover that much spectrum in one
unit that didn't have ferrite in it.
I needed something very similar to match a doublet. I ended up with a
pair of coax baluns (in series - don't tell me!) and I get 1:1 indicated
on the input to the transmatch on all bands 80 to 10. The doublet is
too short for 160m, so is fed as a T on that band, and loaded quite
differently.
The main balun is 14 turns of good quality RG213 on a 4 inch plastic
drainpipe former. The smaller one is 6 turns.
73
Keith
G3OIT
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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