After several months of testing with four 622s, two different antenna setups, and an HDTV PCI tuner card on my PC, I have concluded:
The sensitivity of the 622 OTA tuner varies substantially from 622 to 622. And the 622 OTA tuner is not a very sensitive tuner - as OTA tuners go.
Obviously the 622 is basically a satellite receiver. The OTA tuner to me seems like an afterthought that is not a very good one in comparison to my simple $70 HDTV PCI tuner card in my PC, operating from the same antenna. And as some have noted, an expensive TV probably has a better (more sensitive) OTA tuner. My Samsung DLP has no HD tuner.
I live about 60-62 miles from two HDTV stations here in the country. They are not far apart, so aiming a high-gain antenna is not much of a problem in that the beamwidth will pretty well cover both distant towers. They are in a different DMA from my HD LIL DMA, and get different physical network feeds. So, I am able to compare a lot of things. One OTA station carries NBC - and CW on a sub-channel. The other station is CBS, UPN? (in transition), and FOX. All are digital and HDTV.
Until recently, I had a very old VHF/UHF TV antenna at 50 feet, with no mast preamp - and several missing elements. There was a 12 db Rad Shack distribution amp in the closet, feeding the coax outlets in four rooms. With previous 622s, I got signals from the two OTA towers of 86 and about 80. Most of the time, I could get a good lock on both stations. The 86 one was always rock solid.
Then, I got a replacement 622 (for one which had a variety of problems). When I hooked it up to the old antenna, I got lower signals than with the previous one, and the weaker station would constantly drop out and come back in (Error 739 Signal Lost). Yet both stations were rock solid on my PC HDTV card, as they had been with the older 622 online, of course. The PC HDTV tuner was my constant reference.
So, I put up a new 14.2db UHF yagi with a corner reflector, a 29db mast preamp, new 50 feet of coax and fired her up. No need for a distribution amp, because: On the new 622, I now get 95 signal on the one distant tower and about 90 on the other one. About what I expected with a decent antenna/amp setup.
But..... Even at a sig of 90, the one station and sub-channel will not ever lock in for more than a few seconds. The picture breaks up all the time and every minute or so up pops the Error 739 screen (Signal Lost). In a few seconds the picture comes back and the one-minute or so cycle starts over again.
Remember, with the older 622 and broken up antenna, I used to get this signal with a good lock at signal of about 80. Now, with a "hot" antenna and preamp, the signal will not lock up on the 90 signal. You do the math about the 622 tuner.
On the tower from which I get 95 signal, the picture is perfect, actually more stable than the same Dallas HD LIL channels. This is the OTA with CBS, UPN, and FOX.
While the picture on the 622 with a signal of 90 is breaking up all the time, I can record the same show on my PC card in HDTV and it is perfect! Now, I also have an S-meter onscreen for the PC card. It shows a 100 percent signal from both of my OTA towers.
I can record a total of 5 channels and sub-channels on the PC, all with a perfect picture from the same OTA antenna setup I use on the 622. Actually, the PC coax wall outlet is about 30 feet farther from the incoming coax than the coax wall outlet for the 622. Minor loss, but still counts.
I know from decades of fiddling with HF, VHF, UHF and years of DBS dish pointing and installing different receivers, that S-meters are not accurate. Case in point; going from a signal on one 622 of 80 to a signal of 90 on the new one and losing the signal with 90 on the meter! But, on the same set, an S-meter is useful to compare relative strengths from different towers. I set the direction - while watching signal strengths - and lock the antenna in place. No rotor.
If you live close to a tower, you may overload the OTA tuner on the 622, as has been noted. But, I doubt that at 60+ miles and with signals of 90 and 95, my OTA tuner is overloaded. My PC HDTV programs show no sign of overload, even though the meter says 100% signal.
If you own two 622s, it would be interesting to know what kind of signals you get on the same OTA station on the same antenna. Also, I know there are people on the forum who have both D* and E* HD DVRs. I wonder what kind of OTA signal comparisons you will get when the OTA tuners are turned on with the new D* HD DVR? I may have to add another dish to my antenna farm and another brand of HD DVR to my mess, which includes WildBlue and 3 ham antennas.
