My CTC-16XL Project.

[old_tv_nut]

130 ohms is what you read with the circuit intact. The tube does not need such a low resistance to ground, it just happens to be what is there when the normal circuit is connected.

If you are coupling through a capacitor, you need some resistance to ground to bias the tube, but the smaller you make this resistance, the larger the coupling capacitor you will need to keep video low-frequency response. with 100k load, you need a capacitor of about 0.1 microfarad. If you use 50k ohms (47k standard value), you need a capacitor twice as big, and so on.