RCA CTC-16XH Smearing Issue

[Jon1967us]

Originally Posted by Electronic M

You can't align video IF with a square wave generator. You need a TV specific Sweep and Marker generator.

That TV video IF response curve that looks like a square wave with peaks on the ends is not created by injecting a square wave into the TV. It's created by an IF sweep generator.

An IF sweep generator is essentially an an overcomplicated radio alignment generator.
It generates a wine wave frequency in the TV IF range and contains a 60Hz ramp wave generator the ramp wave modulates (sweeps) the IF output frequency from around 3MHz below the center to around 3MHz above it. So the sweep generator outputs a constant amplitude RF signal (the frequency of which constantly changes such that it sweeps the entire IF passband at roughly 60Hz), and the 60Hz signal is also output. The 60Hz feeds the horizontal axis of the oscilloscope, and the vertical axis of the scope is fed from a demodulator probe connected to the TVs IF.
Basically the sweep generator and the scope form an RF curve tracer (or primitive RF network analyzer if you are familiar with RF network analyzers) that traces the IF response on screen by feeding the TV IF input a constant amplitude signal that sweeps it's frequency response range, sweeping the scope horizontal in sync with the frequency and ploting the non-constant output (which is the response curve) on the scopes vertical axis.

A marker generator is basically an RF wine wave generator with very precise frequency. TV specific ones can create multiple marker frequencies simultaneously and usually use crystal oscillators. You can use a modern digital RF generator or even an old tube radio RF generator (and a modern digital frequency counter to precisely adjust it) instead or in addition to a TV specific marker generator.
The marker generator adds extra fixed frequency energy to the signal injected into the TV IF creating a thing vertical line above and below the response curve on the scope to tell you if your response peaks are at the right frequency (because the sweep generator sacrifices frequency precision/accuracy to perform the sweep).

If alignment is a complex involved process that requires a lot of specialized equipment, knowledge and practice (it's nearly as much art as science) to do well.

No, this isn't for alignment. My BK 415 will be for that. This is a quick test procedure to check video response (for troubleshooting/location of bad component)

Here's an illustration
https://ibb.co/Z2FH3TQ