We've done some live broadcasts for Christmas parties before. There was a camera and a t-band modulator at the party. We were able to tie it into the existing catv system, transmit it back to the head end and put it out on the system at a unused channel. At first I could only get in black and white till I figured out my t channel was at the diplex filter roll-off freq.Also make sure the t band freq you are using isn't being used for something else, modem returns etc. Also make sure there are no ground blocks or high pass filters in the path.
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