Originally Posted by GroundUrMast
Last question first... Let's try to make the C2V work before giving up on it. Yes, there should be a bit more separation between the two antennas. Two feet is pretty close together, enough to significantly detune both antennas. Three feet of separation would be the minimum... more is better in most cases. If I am using a 5' mast, I generally have room for only one antenna. Correct this issue first... it may be all that's needed.
Are the antennas in the attic or outside in the clear? If they're in the attic, please, test reception outside, clear of the building penetration loss and added RF noise.
But, back to the first and most important question, can the antenna, by itself, produce a reliable signal. If not, you need to experiment with changes of aim, location and elevation... If those don't provide reliable reception, then a change in antenna may be needed. If the antenna plus a preamp is able to produce reliable results, it suggests two possibilities,
(1) The antenna is collecting almost enough signal to deliver reliable reception, but there is so little effective noise margin that you may not be able to distribute it to multiple tuners due to the noise and distortion added by distribution amplifier, splitter and cabling. (The solution would be to experiment with changes of aim, location and elevation and, if all that fails, consider a different antenna.)
(2) The test tuner has a poor noise figure and the preamp is able to overcome the issue. (If this is the case, a better tuner would be able to do OK with the unamplified feed direct from the antenna, and the correct combination of antenna + preamp + distribution amp and passive losses in cable, splitters and combiner may deliver usable signal to all tuners.)
Re. the FM trap, presuming you have a preamp at the antenna, you'll need a short (1' to 3') RG-6 cable connected to the antenna matching network/balun/transformer and the other end connected to the trap. The cable that leads to the preamp input would connect to the output of the trap. If no preamp is present, then simply connect the down-lead to the output of the trap, or, locate the trap at the end of the down lead before any distribution amplifier. If you have strong FM signals close to you, you can use both the external trap and the preamp's internal trap. I expect the C2V to be more affected by FM if there are any strong FM signals present, but the UHF only antenna could be impacted also, if the FM signal(s) are strong enough.
Consider the attenuators an experiment, to be conducted once we have reliable signals at the antennas. Other than observing the results, (ie. does reception improve or not?) and the signal meter in the TV or DVR, there's no consumer grade test devise to connect. I'd simply install an attenuator on the antenna ports of the AC7... Then if I had another attenuator I might also install one on the output. Given the cost of the parts, it seems to be a fairly low cost experiment. This is not the place I would start... I'd need to know I had usable signals at each antenna first.
The AC7 does not need to be at the antenna location. It's a passive device and will not add any significant noise to the signals like an amplifier will. A preamp will add some noise, so it will do best when fed a signal that has not been attenuated by a long cable. If the antennas are receiving a signal with enough quality, amplification can be used to overcome the losses in the cable, attenuators, combiner and splitter. If the antennas are not receiving signals of sufficient quality, amplification and or filtering is quite unlikely to solve the problem. This is why I'm suggesting that the quality of the signals at the antennas be checked (with no amplification) to begin with. We need to know there's adequate signals to work with.
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