Just Caught first HD I've had a chance to see from WPTO-DT 14-6 -- Looks like they are timeshifting PBS HD/widescreen programming(Great idea!), as it is NOT the same HD schedule as the PBS HD Channel Feed on WPTD-DT, WCVN-DT+WCET-DT.
Unless it's a "mix of intermod" you're seeing(Ch 2+7 especially then 16/22/26/45 and Perhaps "herringbone" from Dayton FM stations, as well or mixes of those are probably showing up here, there and almost everywhere they shouldn't be ... This is a visable effect of "intermodulation distortion(IM) likely being created because the preamp is overloading .... If it isn't a "mix o' IM effects" .... The station you see on 54 is likely WCVN (KET/PBS) Covington, KY. If so, there would be a KET1 Bug down in RH Lower corner. Its Digital is on RF channel 24. Could be a bit of short range "tropo", I suppose but otherwise, I'd be sort of surprised that you would be seeing WCVN and not see anything from WSTR 64, although stranger things certianly have happened
One more suggestion FWIW -- You Might be able to get both Cincy and Dayton on one antenna heading, but I'd think you would probably also benefit from adding a rotor as well when you get the antenna "fixed", as Columbus stations should be "in range" for you as well ...
In addition to preamp overload/Intermod problems --- Sounds like you're just not getting enough signal From Cincy stations(or you're just getting too much noise from the preamp) --- Hard to say --- I could see 48, and even 40+55(its tower is near Bellbrook BTW) being a bit snowy, but, unless you have a "serious" enough Nearby terrain issue in that direction, even with the antenna a bit off target I wouldn't think 19 should be all that snowy .. Heck, I lived in Fairborn(on N Broad ST, quite Near I-675) in the 80's when going to WSU, and WXIX 19 was only a TAD snowy on Rabbit ears in 3rd floor apt(brick building with the most "walls" to the south).
So, I have to wonder if there is a possibility that there is something else "wrong" as well, such as a bad connection somewhere, unless the preamp is really "messing things up" even more than "seems" apparent ... as I'd think with that setup that you really should be seeing better results ..... Although, according to the Gain/pattern specs on the 7084 ( here(requires Acrobat reader: http://www.winegard.com/offair/pdf/hd7084p.pdf
) on Winegard site, it DOES seem like it has quite a "tight" pattern(excellent directivity) - especially on UHF ...
On the RS distribution amp -- Yeah, I'd get rid of that thing -- Hard to say, but things might even work better if you take the thing out of line(Might want to try it with just RG6 between antenna+STB (no splitters) to see what you get). I don't think they are talking about Insertion loss with the I/O(input/output) return loss figure(at least I hope not) -- I don't really know WHAT they are talking about there.
Although something with about 15-20db gain 3-5db NF or so would probably be right along the lines of what you are looking for -- I'd stay away from the "adjustable gain" models, they don't seem to work too well "generally speaking" ... IF you would need to "adjust gain" to keep the front end of receiver from overloading(probably should not be an issue for you, but who knows) one of RS's adjustable atteunators would be better. Remember Though -- preamps don't really "add gain" or amount of signal the antenna is "pulling in" --- They Can compensate for losses from the feedline run/insertion loss from splitting signal AND, a Hi-quality amp can lower the overall "noise figure" the front end of your receiver "sees" ... IF the preamp/front end of receiver is not overloaded and creating "extra noise"(so to speak) all over the place. ( i.e.: intermodulation distortion or, "desense" if its the receiver overloading although(I could be wrong) the latter is probably pretty rare with TV/DTV receivers but NOT FM receivers) that is ...
Anyhow -- Winegard/Blonder-Tongue and Channel Master make some nice preamps that are fairly good at not overloading when you have strong signals mixed in with the weak ones, although if you are "too close" to The Dayton TV antenna farm (or any strong nearby source of RF on VHF/UHF frequencies, as these preamps are quite broadband) -- It might get difficult to get much real benefit from a preamp w/o trapping out the strongest signals(which can get "complicated" and expensive ...).
Anyhow ... You're probably going to want to go with a mast Mount preamp instead of a distribution amp for best results, although, I have heard some folks who have tested a Motorola Drop amp(about 15db gain if I recall correctly) that is out there that seems to do VERY well when "overload issues" are a problem. Don't recall the Part #, but I think Best buy might have them. Generally though -- IMO For best results for OTA however, you'd want to get the amp as CLOSE to antenna as possible -- meaning on the mast itself ... With a mast mount preamp --- The amp itself goes Close to antenna, on the mast+is fed DC power via the coax -- The power supply goes in the house(so you can plug it in to A/C) "somewhere" BEFORE you use any passive splitters.
Personally, I currently use a 20+ year old Blonder-Tongue "suburban II" mast mount preamp with about the specs you are probably looking for, although it's hooked to a 300ohm antenna(with balun on circut board of the amp), but from the specs on the 7084 looks like you'd want to get a preamp with a 75 Ohm VHF/UHF input.
This place has most of what B-T, Winegard+CM offers(among other things -- Here's their B-T preamp page: http://www.starkelectronic.com/btk1-1.htm
-- There's also a place in Dayton Called "Wintronic" that I think can get the B-T, as well as CM stuff : http://www.wintronic.com/daytonwintronic/index.htm
I know a lot of people are using preamps like the CM7777 Which might have a little TOO much gain for you+thus overload a little too easily given the Nearby dayton stations, and also that Cincinnati isn't all that much "different" heading wise, which would make it difficult for your antenna to reject much of the strong signals from Dayton "off the side" when you're aimed towards Cincy -- Although, even the CM7777 is known for not overloading "too easily".
I'm not real sure what you are asking about the Multiswitch -- I don't use sat or Cable, and don't know much about that stuff so I probably can't help much there (Doc probably can though) ...
Only thing I could offer would be -- IF you weren't using a preamp -- I'd say It would probably help to reduce your cable run as much as possible -- And/OR get rid of the splitters or anything between antenna+receiver w/ any sort of insertion loss -A Multiswitch/diplexor WOULD have some insertion loss as well, I'd think moreso than 100' or so of Coax except for some very expensive multiswitches out there I've heard of ($$$'s but I don't know) ... BUT with a good preamp(if you can use one w/o it overloading) --- I wouldn't worry too much about the Coax run at 100~200Feet --- A good preamp should easily take care of that, as well as insertion losses to split the signal some "number of times", although hard to say HOW often you'll be able to split before it makes "enough" of a difference.
I Don't think you'd be able to use diplexors to combine feed from Sat dish/OTA antenna IF you are using a mast mount preamp, as it would "mess up" the DC Voltage that needs to go from the power supply in the house to the preamp on the past. There may be a way to make "something" like that work given the right equipment, I don't know.
Let us know how it goes,