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RVonse, thanks for your comments. It's valuable to hear opinions from someone who has seen a lot of these sets. I suspect that there was variation from set to set of the same make due to variations in tube characteristics in the high-level stages (video output, color demods or color difference amps), so judgements based on a fair-size sample are important. The '67 Magnavox I recently bought from Doug Harland shows variations when substituting the video out, and when you look at the circuit you see it's running nearly maxed out with very little degeneration, so you would expect max gain (contrast) to vary from tube to tube. Similarly, with the RCA X-Z demods and the following 3-triode common-cathode matrix to make R-Y, B-Y and G-Y, the matrix gains depend on the tube dynamic impedances as well as the common cathode resistor.
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