[R-390] Re: More Stuck Slugs

[Drew Papanek]

Patrick wrote:

>If the slug is stuck, it must not have been moved for a long long time, 
>that means to me that it is in >alignment, leave it alone.

It may or may not be in alignment depending on motion, drifting capacitors, 
and aging characteristics of the core material.  Core permeability tends to 
decrease with aging and hence inductance drops.

But this is an R-390A we are talking about.   The bandwidth is determined by 
the mechanical filters and the IF is otherwise broadly tuned; exact 
adjustment is not critical.  Yes, if maladjustment were to cause the IF to 
become broader then the IF's noise contribution would increase, but by how 
much.

The R-390A 's IF has far more gain than necessary and so we reduce it by use 
of the IF gain control.  There is sufficient reserve gain to compensate for 
a little IF misalignment.

Drew