[ARC5] Selectivity in ARC-5 receivers.

[Kenneth G. Gordon]

Dennis reminded me that increasing selectivity by reducing the coupling of 
the IF transformer's coils will help at the 6db point, but no so much at the 60 
db down point, the reason being, of course that at the 60 db down point, the 
ultimate selectivity approaches the 6 db per octave rolloff effect, and this is 
determined by the IF frequency, not the inductive coupling.....if I understand 
what he told me correctly.

I do remember the 6 db/octave roll-off business from when I was studying 
filters in EE quite a while back.

What this means, of course, is that since the 6 - 9.1 Mc receivers have a 
2830 kc IF, the ultimate -60db selectivity cannot be helped much by 
separating the coils.

Even so, I intend to see what improvement I can achieve. At least I can help 
the 6 db down point...

Kenneth G. Gordon W7EKB

"Courage is being scared to death but saddling up anyway."--- John   Wayne