Hi Jim,
I guess the shorted 160m coil might have been resonant on 10m and the
circulated current caused the heating of the toroid, not the coupling.
73
Peter
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Jim
Sent: Donnerstag, 1. Juli 2021 04:49
To: amps@contesting.com
Subject: Re: [Amps] Swan Mark 1 on 160 meters
If I knew, I would have stated that fack Lou.
Some sort of inductive coupling I guess. Even through the 10 meter coils
was 8 inches away from the 80/160 meter toriadal coils.
It was covered at great length here on the mailing list when I made the
discovery. 8 years ago.
Thanks
73
Jim W7RY
On 6/30/2021 2:37 PM, gudguyham via Amps wrote:
> How does a torrid used on 160/80 meters get hot on 10 meters if it's
shorted out?
>
>
> Sent from the all new AOL app for iOS
>
>
> On Wednesday, June 30, 2021, 2:42 PM, Jim Brown
<jim@audiosystemsgroup.com> wrote:
>
> On 6/30/2021 5:34 AM, Jim wrote:
>> DO NOT use toriods. I speek from experiance. Had a reaction when on 10
>> meters with my 8877 amplifier. The 160 meter toriod coils would start
>> smoking when on 10 meters. I was using a shorting switch.
> "Toroid" is a shape in which hundreds of very different materials are
> manufactured. I know nothing about powdered iron toroids (although they
> are very successfully used in the 5B4AGN-designed bandpass filter kits I
> built years ago), but I know a LOT about ferrite toroids.
>
> The Fair-Rite catalog is a treasure trove for learning about ferrite
> materials. The company has developed several dozen different chemical
> mixes for very specific purposes, and there are mixes that can handle a
> lot of power in specific frequency ranges. These mixes have been
> assigned numbers. In general, these materials have low loss at low
> frequencies, high loss at higher frequencies.
>
> Over the years, a few select companies have published technical data and
> applications notes so detailed and filled with information that you can
> learn as much from them as from colleges and technical schools. Those
> published by RCA (tubes), National Semiconductor, Electro-Voice
> (loudspeakers) are examples. The Fair-Rite catalog is deservedly within
> this group.
>
> The catalog is here.
>
> http://www.fair-rite.com/files1/Fair-Rite_Catalog_17th_Edition.pdf
>
> Beginning on page 10, start by reading the brief description at the top
> of the page for each material, then studying the graph of "Complex
> Permeability vs. Frequency." On this graph, mu' is the purely inductive
> permeability of the material, mu'' is the resistive component, where R
> and X are in series.
>
> For example, in the first entry, #68, permeability is fairly low (about
> 15), but loss is also quite low up to about 100 MHz, where it begins to
> rise rapidly. The next entry, #67, has higher permeability (about 25)
> and comparably low loss up to about 30 MHz. N6RK, a very smart engineer
> who retired from HP some years ago, has used #67 toroids for high power
> transformers.
>
> Ferrite materials are useful as common mode chokes for RFI suppression
> in frequency ranges where they are very lossy. #61 is useful as an
> inductor core (including transformers) at HF, but starts getting lossy
> around 10 MHz (where mu'' starts rising), and is sufficiently lossy at
> UHF that it's useful for suppression.
>
> 73, Jim K9YC
>
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