Edwin Spector wrote:

I have just done some measurements,...snippetty...
Results
Original return loss: 27dB (Very good)
Original insertion loss 0dB (relative, not absolute)
Crude join: IL = 0.3dB at 650MHz, 0.31dB at 750MHz.
Better join: IL = 0.1dB over 650 to 750MHz.

Footnote:
It's probably worth spending a couple of minutes making the joint as 'nice' as
possible. A discontinuity in a TV feed could produce a reflection which could
give a ghost on the telly image.

Edwin.