I was responding specifically to the comment from K4TAX:
"I'll take an air-wound inductor over a toroidal inductor any day, space
available. The typical loss in an air-wound inductor is IR loss where a
toroidal has IR loss plus eddy current loss."
I didn't read that comment as applying specifically to balanced tuner
operation.
If you are asking what is my preference in tuners for twin feedline, it
would be an unbalanced L-match with a good 1:1 balun at the output. If
that L-match needed to be automated and use fixed value inductors, I'd
happily take iron-powder-cored inductors in place or air-cored inductors.
73,
Steve G3TXQ
On 20/02/2013 21:36, Rick - DJ0IP / NJ0IP wrote:
Steve, this thread seems to have taken two paths: 1) "balanced tuners"
(which is what it was initially about) and 2) "Toroids vs. air-core coils in
general."
Focusing on the original topic, balanced tuners, my preference is clearly
link-coupled air-core coils, as used in couplers such as the Johnson Viking
KW Matchbox, and the Annecke Symmetrical Koppler.
Are you saying you would prefer to have a matchbox for tuning openwire fed
antennas built with toroid coils instead of air-core coils?
The application here is a general matchbox, say from 80m thru 10m, and
should be able to match pretty much anything you throw at it.
If you choose a toroid, it's going to have to cover 3.5 to 30 MHz, unless
you have a separate set of coils for the high bands than for the low bands.
IMO, the Air-core coil is better in this specific application.
If there is a better way, I will be happy to learn about it.
For bandpass filters, where each band has its own coil(s), then I agree,
toroids are the way to go. There you will use a different mix for different
bands.
73
Rick, DJ0IP
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