[Penthode]

I have been making progress with the peaking coils. I have managed to repair three and found a way to accurately measure and recreate the missing coils.

I have been looking for a way to accurately measure peaking coil inductance. The best solution which is repeatable is resonating it against a known capacitance. I am using the setup below.

I am series resonating so as I adjust the oscillator, I will find a dip when resonance is found. I am using a 5% 820pF mica capacitor. (I could not find a 1% tolerance cap). The capacitor is slightly higher than 820pF so my readings are consistently a few percent below. But it is close enough.

The repaired 1.9mH measured resonance an inductance of 1.85mH. The 820uH inductor measure 800uH. and the 1.0mH coil measure 980uH. So all is good.

I am now in a position to recreate the 6.7mH and another 1.0mH to complete the set.

When the set is back together, I shall sweep the chroma and luma channels with the new peaking coils to ensure this CTC2 chassis meets spec.