[ARC5] Smart People: Antenna Matching Mystery

[Ian Wilson]

I have noticed that the roller coil has distributed capacitance, so it
does not always behave as a simple inductance even at lowly RF.

To a reasonable approximation, it could probably be modelled as
"a few" L-C sections. 4 would be a good starting point.

73, ian K3IMW

On Mon, Aug 7, 2017 at 6:57 AM, David Stinson <arc5 at ix.netcom.com> wrote:

> OK y’all- here’s a mystery (at least to me),
>
> Series circuit, designed to match a normally 5-12 Ohm
>
> Aircraft radio output to resistive 50 Ohms.
>
> Follow me here:
>
>
>
> Series circuit:
>
> PA Tank coupling link – Roller coil –
>
> 120pFd ceramic cap mounted at antenna post –
>
> 50 Ohm Load = 25 W out.
>
>
>
> PA Tank coupling coil –  120pFd ceramic cap mounted
>
> at the input of the Roller Coil – Roller Coil –
>
> 50 Ohm Load = 15W out.
>
>
>
> The ceramic cap is near chassis ground both ways,
>
> so it’s not circulation currents.
>
> The PA tuning cap setting does not change,
>
> so it’s not de-tuning the PA tank.
>
>
>
> Why the difference between these two series circuits?
>
>
>
> 73 Dave AB5S
>
>
>
>
>
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