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
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Steve Hunt
Sent: Tuesday, February 19, 2013 10:53 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] OT: Openwire Balanced Antenna Tuners (QST Test)
Pretty high Q values can be achieved if you choose the toroid mix and the
winding spec carefully.
For example, according to the Micrometals Q Curve Application Information
book a T200-6 core wound with 30 turns of #18 wire achieves a Q >300 across
the range 1.5MHz to 7.5MHz, and peaks at over 400.
That's significantly better than a commercial air-cored roller-inductor I
measured at the same inductance value.
73,
Steve G3TXQ
On 18/02/2013 01:54, Bob McGraw - K4TAX wrote:
> 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.
>
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|