# Re: Magnifiers

```Hi John, all,
I'd like to add something to John's note for the
benefit of those trying to figure out how to tune a mag:

> Original Poster: FutureT-at-aol-dot-com >
> All,
>
> Magnifiers work very similar to normal classic TC's.  They
> basically behave as a normal TC with the secondary split into two
> sections.  The primary tunes to the combined secondary and extra
> coil frequencies.  In other words, the primary freq will be lower than
> the extra coil freq, due to the presence of the secondary coil.

Very simply, calculate Cself of the secondary and Cself of the extra
coil and add them together. That capacitance must also be added to
effective terminal capacitance to give the total capacitance on the
secondary side. Sum the two inductances, then use Ctot and the sum of
the inductances to determine the frequency to tune the primary to.

You will find that if you take a secondary coil (with, say, an
aspect ratio of 5:1) and chop it into two coils with h/d=2.5 (for
example), the sum of the individual Cselfs is higher than the Cself
of the original coil so a mag made this way will tune to a lower
frequency than the original resonator.

Malcolm
<snip>

```