My CTC-16XL Project.

[dtvmcdonald]

Peaking value coils are never critical. In fact, its sort of silly worrying
much about just the value, unless you can get a for certain absolutely exactly original
factory model coil.

You see, these thing have capacitance across them and thus are parallel tuned circuits. Whether they are used in series with the signal or as a plate load, that resonant frequency matters.

And the "standard replacements" listed are often, while close in low frequency
inductance, way pff in parallel resonance. That can make for a bad picture.

I have an RCA CT-100 color TV with lots of peaking coils that are potted in something white that corrodes them. In fact though some of mine were bad, none were
so bad I was unable to unwind a few turns and get measurements of inductance and resonance. I had to experiment to get the waveforms to look right. I bought
two or three coils for each replacement. The best inductance value varied
up to 35% from spec. Most were noncritical but a couple were critical.

Putting coils in series thus generally simply won't better than just getting close.