Fins,
I've seen problems when DTV transponder signals are below 80. Since it's devlilishly hard to find out what channels are on what transponders, I don't try to refer to the behavior of HD channels... just channels, all channels, any channels.

You're not talking about the same thing, though. I'm talking about the AIM meter, which gives signal strength readings in dBmV, and in fact all the readings are negative. This means 35 on the AIM meter is 15 dB higher than 50. We're just used to not being careful to include either the negative sign or the unit of measure, dBmV. Incidentally, dBmV is the same measure used for TV antennas for years. The rule of thumb with the old analog TVs is that a signal of 1 dBmV was required for reception to be free of snow. And satellite reception pulls programs out of signals 30 dB lower than that!

Transponder signal levels are not actual signal levels. They are some kind of "quality" assessment that doesn't directly translate from signal levels. That's why someone could say that "55 on the meter," which is a signal level of -55 dBmV, roughly translates to 60 on the DTV transponder readouts. And they think that will work but we know it won't.