[600MRG] s/c inductor tuning loops

[Dave Riley]

Also used on low power ( receive ) devices comes the 'slug tuned' 
inductor... I.F. cans etc..

At high power it has to de-Q ...

Brass to increase frequency and ferrite material to decrease F/o...

General Cement sold a small plastic stick with a brass ( non ferrous ) 
slug on one end and ferrite ( ferrous ) slug on the other, came in real 
handy over the years...

GC8278


On 5/8/2018 10:59 PM, J Mcvey via 600MRG wrote:
> The variometer is nothing more than a transformer with variable mutual 
> inductance
> The load will affect the Q more as the coupling is increased, but at 
> least the energy ends up in a load!
>
> ,The tuning disk just wastes energy in heat, which is why they don't 
> use that method any more, IMO.
>
>
>
> On Tuesday, May 8, 2018, 7:50:11 PM EDT, Brian, WA1ZMS 
> <wa1zms at att.net> wrote:
>
>
> I read the write up. Very interesting. That's a much great change in Q 
> than I would have expected.  And as for the variometer case....it 
> would help define an optimum range over which you'd want to bound the 
> tuning range before the Q starts to suffer.
>
> This also says the "dead end effect" of turns on a coil might have 
> been misrepresented from tales of operators from the 1920's. hi...hi...
>
>
> -Brian, WA1ZMS
> iPhone
>
> On May 8, 2018, at 7:13 PM, Rudy Severns <n6lf at epud.net 
> <mailto:n6lf at epud.net>> wrote:
>
> Hello All,
>
> Over the past few days there’s been some discussion of floating short 
> circuited loops or metal discs placed inside a coil to adjust the 
> inductance. The idea absolutely works but it’s a disaster for the coil 
> Q.  To illustrate the problem I ran a quick experiment to illustrate 
> the problem. I’ve written a short note on the work which is posted at: 
> www.antennasbyn6lf.com <http://www.antennasbyn6lf.com>   In due course 
> I’ll expanded this to give a detailed explanation of the phenomena and 
> show a similar but not nearly as serious effect in variometers but 
> this will have to do for right now.
>
> GL and 73, Rudy n6LF
>
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