How to inject a signal into a TV?

[Electronic M]

Originally Posted by ChrisW6ATV

The one thing to avoid is connecting to the plate circuit of a tube (until you are using a device intended for that, such as a horizontal-output tester). Always put a voltmeter on the pin/connection you plan to use before you connect the generator. Then, adjust the generator while looking at the CRT or otherwise testing for the results you hope for.

Quite often, you cannot actually clip the signal to the circuit but have to just hold it there while looking at the screen.

That depends on the signal generator. My B&K 1077 has no issues with signal plate circuits....The video signal output socket on it has a large series capacitor feeding it signal to block DC....I've used and X10 scope probe for the RF/IF lead (the only thing I have with BNC on one end and clip-leads on the other to act as a test lead for it ), and used that to feed signal to IF plates without issue......Even generators not meant to feed signal to plates or the like can do so safely WITH a proper DC blocking capacitor added in series.