Hi Peter I think this is analogous to putting an aluminium or brass slug
into a coil as with the VHF Toko range where there is an optional ferrite of
aluminium.core. I have never measured Qs I suspect it is a bit lossy maybe
that is why a single shorted turn is used for a loading coil.

Alan
G3NYK

----- Original Message ----- 
From: "Peter Dodd" <[email protected]>
To: <[email protected]>
Sent: Saturday, January 29, 2011 11:10 PM
Subject: LF: LF coil tuning


> The traditional method of tuning an LF loading coil is to use a
variometer.
>
> I have been investigating methods of tuning coils for mobile use and one
> method that appeared briefly  in one of the ARRL Handbooks of the 50s
> was the shorted turn method of tuning.
>
> I tried a home made coil of 136uH on a 5cm diameter former and using a
> shorted turn of 2mm insulated wire and obtained a tuning range of 32uH.
> (136 - 102uH).
>
> Has anyone out there tried this?
>
> Regards
>
> Peter G3LDO
>
>
>
>
>