[Radio Wrangler]

An inductor in an IFT is set to be too low L on its own. So that an adjustment slug can be added to shift the L either side of nominal. So the slug can take the L a bit too high or a bit too low.

So correct adjustment will have the slug stuck out of the coil. It could be either side and still get the same L.

Now, an IFT has two of these coil/slug arrangements.

Each can get the right L with its slug in either of two positions.

However, the slug hanging out on the side nearest the other coil increases the coupling to that coil. This applies to both slugs and there are four combinations.

USUALLY the wanted setting is witht he slugs extending outside their coils and away from each other. Designers choose this to get their wanted amount of coupling without needing a bigger IFT to space the coils more.

Hence the usual instruction to go for the first peak as you fit the slug from the outside.

David