The tuners are a complicated issue. I've been experimenting with them for hours. First of all, don't believe everything you see...the tuners are really "finicky"...that's the best way I can put it. They show completely different signal readings depending on all sorts of things, including the length of line feeding them.
Some observations to support "finicky"
1. Varying the length of the line (inserting known good sections of varying length), produce dramatically different readings, even between tuners. I was able to get PBS to show a difference of of 40% between tuners by varying nothing more than the length of the line.
2. Varying the amount of signal (with a preamp ... a real, low noise preamp, not a noise generator) can produce the same issues.
3. Varying the amount of signal with a variable attenuator showed similar "tilt" toward one ctuner or the other.
4. Varying the amount of signal with this same attenuator produced large variations of signal strength between channels.
All my stations come from one tower complex, located 27 miles from me, across largely flat terrain (few rolling hills). All are on UHF from channel 16 up through channel 59 (real channel not remapped). My antenna is a medium sized VHF/UHF LP-Yagi on top of a two story house with new RG-6 feedline of about 40'.
Let's just say while the tuners in the HR20 work reasonably well, they have some real "issues" that will need to be worked out. The signal strength meters are not to be relied on. Anything one might do that produces wildly different levels on the two tuners is probably headed in the wrong direction. Anything one can do to get them closer together is probably progress.
It is not a good sign that varying line length in short sections produces wild variations in apparent signal quality.
I have found the following setup to work best for me:
ANT > Main Feed > Preamp > Variable Attenuator > 3 way Splitter >
> Samsung HD TV
> Panasonic DVD Recorder/SD Tuner
I have experimented with all possible variations...running the main antenna line directly into the HR20, using or not using the preamp, using or not using the variable attenuator (with various levels of attenuation), changing line lengths in all of the previous combinations.
EVERY CHANGE MADE A DIFFERENCE IN HOW THE SIGNAL METERS IN THE HR20 BEHAVED..and I'm not talking just about strength...I'm referring to stability of the meter readings and equalization of signal level of the two tuners.
So, don't try to make too much of readings on the HR20 signal meters (OTA). Seeing good from bad is fairly easy...making smaller discernments is presently not possible, so don't miss the forest for the trees.
Signal Strength, Load Impedance, Line Length, Multi-path...all influence what the meters are saying. At this point it is VERY difficult to arrive at any sane conclusions other than having both tuners read as closely to the same signal (and as strong a signal) as possible is good.
At this point, we are going to have to experiment a bit.