[AMRadio] Classic Link Coupled Tuner

WA5AM ars.w5ami at gmail.com
Sun Aug 16 06:53:06 EDT 2009

Wow!!  Thanks for all the great ideas, and comments.

As is, I think I have a spot tapped that works well, however using such
little coil tells me there may be some side effect.  No, there is absolutely
no heat.  Never has, even with full legal limit AM 100% modulated for 10

I took  a photo taken this morning of the tuner here that should give some
idea of the size.  I put a shot glass in the photo for scale:

The things that come to mind for me are where I am tapping the parallel cap,
and my feedline length.  As you can see, there is a lot of extra coil beyond
where I currently have the taps for 75 meters.  That extra coil will never
be used on the ham bands.  I think I will try tapping the cap out several
turns from where the feedline taps are, but not at the ends of the entire
coil.  I will try this after setting the 75 meter taps at about 22uH and see
if there is any indication of resonance.  I think having the cap and
feedline tap in the same places on the coil is a possible problem.

If that doesn't seem to help, I will take a look at my feedline length.

73 & Thanks for the help!

Brian / wa5am
PS: John, sure would have been nice to meet up for a cup of coffee had I
known you were close by!

On 8/15/09, John Coleman <jc at pctechref.com> wrote:
> Thanks Bob
>         Just to add a little something: Someone said earlier, something to
> the effect, that there may be a non resonate antenna and feed line
> combination that can cause a lot of trouble.  This is very true because then
> the L and C of the tuner must add or subtract reactance in order to make the
> whole system resonate.  This is often more easily done when you have a lot
> of capacitance to work with.  So having a high Q tank in the tuner has its
> advantages.
> John, WA5BXO

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