[Penthode]

You mention the fine tuning adjusts full range. On ch4 on the 721TS the full fine tuning range is only about 0.5MHz where each channel is 6MHz. So the fine tuning is very narrow.

So I switched on just now my 721TS on channel 4 and adjusted the fine tuning across its full range. The pictures attached below depict what you would normally see on a properly aligned set.

The first image is with the fine tuning fully clockwise. Note the picture is brightest because the video carrier is at the top of the response curve. As a result the picture will lack fine detail. And there is no sound.

The second image is with the fine tuning roughly center with the picture a bit dimmer but with full detail. This is the correct point where the video carrier is at the 50% point on the video bandpass slope or nyquist slope for vestigial sideband demodulation. As this is a spilt sound set, you must adjust for best sound which would be the discriminator zero position.

The third image is with the fine tuning control fully counter clockwise and the picture is very weak. It has trouble locking because the carrier is at the bottom of the slope. There is no sound.

So as you adjust the fine tuning control counter clockwise, you should see the picture grow gradually dimmer if the tuner's local oscillator is set correctly within range of the tv signal. Either end of the fine tuning control there will be little or no sound.

If the image brightness remains the same across the tuning range or if the image grows a bit dimmer when the fine tuning control is clockwise, then the local oscillator is off frequency and you will get no sound.