[R-390] 1st IF tracking problem solved

[Jacques Fortin]

I agree with Dave.
Having a green dot on an IF slug is not a proof that it have the proper
relative permeability.
The relative permeability of the IF slugs (AKA the "green" slugs) HAVE TO BE
4.
I checked this by winding a layer of 26 AWG, Teflon covered solid wire
around a "good"  slug, and measuring the resultant inductance, then, by
removing the core carefully (so keeping only the self-supporting winding)
the measured inductance dropped by a factor of 4.

Same kind of test applied to the RF slugs gives a relative permeability of
10.

I also found some slugs in a '56 Motorola RF deck (which came from Fair
Radio) that measured a relative permeability of 7 and were bronze in color.
No idea from where they came from, but they surely caused alignment
troubles.

73, Jacques, VE2JFE in Montreal