[HBR] IF Transformer Theory Questions

[Byron Tatum]

Hello-
    If I could bother anyone with the knowledge and experience in working with tube circuit IF transformers I would like some help in these areas: (455 KC units)
    1. The subject of reversing the leads of one coil, and said coil is wound in opposite direction of other coil. I noticed this done on an IF transformer, in comparing it with a very similiar one using the same coils, same spacing, perm tuned, and same fixed capacitors. The former transformer was rated at 9 KC selectivity at 6 dB down (diode transf.), the latter was rated at 12 KC selectivity at 6 dB down (input / interstage transf.).
        What occurs if you simply build an IF transformer with coils wound in opposite directions, is the coupling greatly reduced? Is this why they also swapped the leads around on the coil wound in opposite direction, to only slightly reduce the coupling and gain an improvement in selectivity?
    2. I am having trouble finding any technical information on the differences in IF transformers as far as input, interstage or output. Typically the coil on "input" side {plate conn.) of IF transformer has less inductance than coil on "output" side (grid conn.) of said transformer. I have noticed on most transformers the plate circuit coil will close to one-half the inductance of grid circuit coil. This seems to be the case for input, interstage or diode load transformers. I believe the reason for the difference in coils is impedance matching? I had the understanding that most diode load transformers had closer spacing with the goal to be more coupling, with selectivity not a priority. Then, I come across a diode load transformer that has greater selectivity than the matching interstage transformer.So, I wonder " Can I use this diode load transformer as an input or interstage transformer?" What different impedance does the transformer see when operating into a diode load as compared to an IF amplifier grid?