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For RCA color sets of that era, the video (Y) response is totally dependant
on the peaking coils.
And if replace one or more, it can make a huge difference!
You see, RCA (and Sams) specify only the nominal inductance.
That's not what determines the frequence response.
What determines it is the parallel resonance frequency of the coil plus
circuit capacitance.
How I got the perfect picture I have on my RCA sets is getting the right
peaking coils. Except for the 6.8 mH coil in the CT-100 "Q" (use 3.3 mH)
the specified values are just fine. When getting coils, rummage through
Mouser and Digikey for the little molded axial coils, shielded is nice, from Bourns, Miller, and API Delavan. Get ones that have resonance frequencies
well above the needed value (e.g. above 7 mHz for Y, above 4 for I, and above 2 for Q or narrowband color). Higher is better. Get some tiny ceramic or
mica caps at 1, 2, 4.7, and 6.8 pf. Parallel the caps with the coils to your taste. Use one of the the test DVDs for NTSC. Don't use a regular scope probe. Use a short (2-5 foot) piece of coax to the regular 1 meg scope input
with a 1 or 2 pF capacitor in series with it right at the point of attachment with the TV.
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