This might be important info as far as tuning digital channels with the 3575/3576/2160... altho in a roundabout way since this relates specifically to tuning digital channels on my newest LCD TV.Background
For awhile now, I've had two Vizio LCDs, a 47" 1080p and a 37" 720p (768p), both with 3575's attached.
My cable run to those 2 TVs was ~50 feet, with a cableco amplifier in the middle of two 25' RG59 coax cables from a 3-way splitter at the cable drop into basement.
All TVs and 3575's tuned 10-15 digital channels, including 60.1, 60.2 and 60.3, with no problem for more than a year. (Note: these 3575's also slightly amplified the cable signal to their attached TVs via coax passthru.)New TV Added
Got a new (3rd) Vizio 32" 720p (768p) LCD and set it up on a separate coax from my basement, but with no 3575 attached for passthru amplification.
Scanned for channels and the TV tuned everything EXCEPT the digital 60 group.
Tried many more scans, with no success in tuning the digital 60 group.1st Test - Connected a 3575 to the New TV for Signal Amp.
I connected a 3575 to the new TV, scanned for channels, and again no luck with digital 60 group.2nd Test - Moved Cableco Amp
Trying to decide if maybe new LCD was "defective" but had an epiphany that it was the ONLY component NOT connected to the cableco amplifier on my incoming cable TV coax [basic (analog) cable]. This TV was connected directly to the 3-way splitter at the cable drop via a 25' RG59 coax i.e., no cableco amp on that coax.
Switched position of amplifier to 1st on the incoming coax so ALL components received the cableco amp's signal.
ON 1ST SCAN, WITHOUT A 3575 IN LINE, NEW TV TUNED ALL DIGITAL CHANNELS AS OTHERS, INCL. THE DIGITAL 60 GROUP.Conclusion?
My conclusion so far is that the 3575's coax passthru amplification wasn't enough to beef up the signal for that channel group, but the cableco's much stronger amp DID.
I'm thinking my 3rd TV suffered the "Cliff Effect" or "Digital Cliff" I've been reading about... and described in more detail here.
This effect is a complete loss of digital signal at the ends of its ideal signal strength too low a signal or too high a signal can make digital channels just "fall off the cliff" (disappear), as opposed to analog channels that get increasingly snowy towards the lower end of their signal strength... and we're always trying to maximize analog's upper end.Moral of This Story
If you suffer loss of digital tuning, try "rearranging" splitters and amps cuz you may need to either INCREASE or DECREASE your incoming signal strength, even if your signal loss applies to only certain digital channel group(s).
You may need to add a good amp OR a good attenuator to get the ideal signal strength for digital tuning WITH OR WITHOUT A 3575/3576/2160, as my experience with a new TV
An easy test for too-strong a digital signal is the "hang-by-a-thread" test... unscrew incoming coax so it's hanging on by a thread and make sure center wire is no longer firmly seated. This can attenuate the signal just enough to see if signal might be too strong.
This may or may not help someone else in a similar, "odd" situation such as I ran into!?