[AMRadio] Ferrite slugs for SX-28A

[rbethman]

Slug replacements may be possible from scavenging from old hulks of like 
manufacturer.

Perhaps even something as unlikely as an S-120 that is out in the shed 
or barn.  While the composition of the ferrite material will likely be 
different, there is a reasonable probability that it will work, just 
with a different location within the coil form.

We can usually find a way around that we hadn't considered earlier.

Bob - N0DGN