Tunable loop antenna help needed

[jimbofish]

Some time ago I set out to build an AM loop antenna from a 14" embroidery hoop. Using one of the formulas available somewhere, I put 17 turns of #28 enameled wire side by side, then set out to find an old radio to salvage a variable tuning capacitor, as it didn't appear to have much effect when connected directly to the ant terminals on a CCRadio.

Fast forward about 2 yrs and many detours later, I finally got a nice VC from a Grundig radio. Connected the loop to it, experimented with an old transistor radio and was able to get some stations to come in more clearly, but not as much improvement as I expected. I haven't tried adding a second pick-up coil as most of the radios I want to use it with don't have ant terminals.

So, I'm wondering if there's a problem with the way I wrapped the loop or the type of wire I used. I placed the wraps of wire side-by-side, closely packed. Should I have spaced them apart a bit? Or used heavier wire with insulation?