When you switched the modulator to cable 73, did you change your TV to channel 73? Did you do that without resetting it to cable? If you did, then it had already been changed to cable, so it wouldn't see UHF 22 as 22. But it would have seen it as 73!

Years ago, when cable was the highest tech around, I would occasionally have interference in cable systems. The channel numbers that were interfering made no sense. Turns out, the interference was from broadcast stations that were leaking into the cable. This problem kept busting my head until I sat down and looked carefully at all the channel numbers and frequencies. I found that if you add 51 to a UHF channel number, you will get the equivalent cable channel number...at least, close enough in frequency for a TV to lock onto it.

That is why many of my cable systems had interference on 79; local UHF 28 was REAL strong, and this showed ingress. But now I had a tool to go looking for ingress, because the channel numbers were now predictable.

This breaks down somewhere around cable channel 90, but I haven't had enough problems to have to learn that equivalence.

This also explains why modulators that go from UHF 14 to 69 start at cable 65... 14 + 51 = 65. Also why, if you have ingress, you won't have problems between cable 13 and 65. Also, since antenna amps are built with two amp sections, one for 2 - 13 and one for 14 - 69 (cable 65 - ??), if you use an antenna amp with a cable signal, the channels in the middle will perform poorly. In fact, poor middle channel performance, say channels 40 - 50, is a good sign that someone used an antenna amp in a cable system.