: Signal Amplifiers (Amps, Preamps, Distro Amps) - See Chart in Post #1
2012-03-15, 11:56 PM
My set-up is similar to yours with my antenna on the shed's roof 9 feet off the ground and a CM7778 pre-amp.
There is some hacking you can do with your CM4221HD, like removing the 8 little plastic covers on the elements and flipping the balun; but don't touch the reflector.
You can also come on the french forum http://www.digitalhome.ca/forum/forumdisplay.php?f=119
With your TV Fool http://tvfool.com/index.php?option=com_wrapper&Itemid=29
2012-03-20, 09:32 AM
should i be looking at a preamp or a distribution amp?
usually for the buffalo stations they are showing in the high 80's on my tv for signal strength, but watching the ncaa tourney on cbs this weekend, i had some dropouts here or there.
antenna is pointed at buffalo, i'm getting cbc in the 90's, but other toronto channels are flaky.
would one of the amps be a solution to this problem? i'm thinking a preamp would be the way to go, but just looking for a more educated opinion.
i'm in oshawa, btw.
also as far as more info on my setup, cable run is probably about 60-70' to that tuner and split once there as one goes to my htpc and one directly to the tv. in the near future i'm looking at a split higher up as well to run a line to 2 bedrooms upstairs and then the 3rd line down here to my original location.
2012-03-20, 04:46 PM
the reason why it was flakey over the weekend was because of the fog over the lake.the lake is still approx 40 degrees,and the unseasonably warm air sitting over it is creating it.it should be better on the weekend as a cold front is going to move through,so things should be back to normal.
2012-03-21, 12:18 PM
Not sure if this is the best place to pose my question as it touches on many topics ... but here goes.
Currently employing a CM 777 preamp on my DB8. I would like to split my home run down feed (about 60feet) to drive least 3 TVs and 1 (maybe 2) stereo receivers near those TVs for FM reception. Currently I have 3 home runs from the TVs to the basement which I have the down feed. The longest TV length is probably 50 ft. Currently, the signal strength appears to be good when driving 2 TVs (don't have a 3way splitter to test with). I was thinking originally of just using a ordinary 4 way splitter to do the primary distribution. And then I could further split the home runs to the TVs for the stereos. Would be better to use a distribution amp (like CM 3414) instead of the ordinary splitter? To compensate for any signal loss?
In the near future, I hope to add an Eagle Aspen ROTR 1000 rotor to the mix. Reading from the ROTOR thread and Willspin's result I believe I could drive this and the pre-amp by using a single cable. I just need to make sure any splitter has a DC bypass. I don't believe the CM distribution amp offer this feature. So then I thought ... would those "switches" that I hear satellite people use work for me? I think those switch have multiple ports and DC bypass. It looks like a "splitter".
Any assistance would be appreciated.
2012-03-21, 01:05 PM
So then I thought ... would those "switches" that I hear satellite people use work for me? I think those switch have multiple ports and DC bypass. It looks like a "splitter".
A satellite multi-switch will not be of use to you.
2012-03-21, 01:54 PM
threeflags. A CM-7777 has more than enough gain to drive through a 4-way splitter and 50 feet of cable. Even adding an additional split for FM shouldn't be a problem (though if you don't need VHF-LO, I recommend using an HLSJ instead of a splitter for that).
One important note, if you have an unused port on a splitter, make sure it is properly terminated with a 75ohm terminator.
2012-03-21, 02:28 PM
Thanks for advice ADTech and Roger1818!
Sogging through the many posts I also came across #2867 which pretty much said the same thing as what Roger1818 said. I haven't read through all of the posts :o. Now to look up what is a HLSJ.
That's one less piece of power equipment (distrib amp) to worrry about.
2012-03-21, 02:35 PM
^^^Check out this (http://www.digitalhome.ca/forum/showthread.php?p=1396123#post1396123) post. ;)
2012-03-22, 09:56 AM
thanks, but are there other weather situations that could cause 'flakiness'? is there something i should do to my system so that this doesn't happen in the future (one of the discussed amps) or is this a freak occurance that probably won't happen again for a long time?
2012-03-22, 11:43 AM
^^^With a 60-70' and a splitter, your 'flakiness' will be greatly reduced by the installation of a pre-amp. Which pre-amp you choose depends on your local conditions and what you are hoping to achieve.
2012-03-22, 01:35 PM
what conditions should i be taking into consideration. main thing i want is rock solid usa channels from buffalo. right now i receive them in the low 90's consistently.
on sunday that was dropping from that down to 50-60's and back up etc with nbc dropping right down into the 20's and thus losing out altogether.
i also want the toronto channels and don't want to overload those, although i'm not sure if that's an issue being that i'm in oshawa, so it's not like i'm right next to the cn tower or anything and as others in the area know that cbc is very strong.
2012-03-22, 02:09 PM
^^^The strength of your strong (local) stations and how well they are being received by your antenna. Strong local stations can overload a pre-amp affecting your ability to receive weak stations.
2012-03-22, 03:03 PM
here is my tvfool report if that helps at all
as i said earlier, buffalo channels come in low 90's, cbc for instance being the strongest toronto channel is usually 98. antenna is aimed at buffalo.
2012-03-23, 08:39 AM
takeaim, See post #2991 (http://www.digitalhome.ca/forum/showpost.php?p=1396249&postcount=2991).
2012-03-23, 08:52 AM
i did look at that the other day but i didn't really understand how to use the spreadsheet.
2012-03-26, 10:23 AM
ok, i looked into the sheet more (guess i wasn't paying attn to it before) as i input figures into the input values section. the data i used from my tvfool report-
uhf channel- real channel
transmitter erp- effective erp
and the distance from the report
all other fields i left as is, as i figured those are good estimates.
the overload chart says to keep below -10db and best below -15db, every channel in my calculation is below -15 except wnlo shows as -13.5, next is tvo (cica-tv) at -17.7, so i would think i'm safe to introduce a preamp to my system and try real world testing? opinions?
as an aside- looking at my calculations, how low of a db figure could i get that would still allow me to receive the channel? ie. the rochester abc (wham-tv) shows as a -31.5 in my calculation chart. ie. how do you read the tvfool signal power column? and thus with a preamp, what could you theoretically pull in?
I have doubts about this amplifier, which is less then 1 yr.
I tested it on all channels. without the amp, all channels were SNR=27, except RF #13 (ABC), and RF #49, which were 13-15.
After adding the amplifier, none of the SNRs changed, nothing. However, I put the amplifier AFTER about 50 ft of cable.
I thought it would show some improvement on SNR, or at least improve (receive) RF #13, RF #49, which it didnt, cause I put it before a splitter, and another 40 ft of cable, and the tuner, which I assume has NF of at least 6-7 dbs
I measured output voltage to be .054 volts
does this make sense ?
2012-03-26, 07:46 PM
No amplifier can differentiate between what's signal and what's noise. They just amplify whatever they receive within their operating frequencies. I believe you're confusing SNR with signal strength.
Ok, but in all channels, nothing changed !, i should have received more signal or locks on more channels, no ?
i only have the hauppauge 950Q tuner stick SNR scale to rely on
2012-03-26, 08:04 PM
A pre-amp can only help overcome losses between the antenna and tuners. Typically cable loss, insertion loss from splitters, F-81's (female to female connectors), etc.
Likely the strength of these difficult stations of yours is below the receive threshold at the antenna. And since pre-amps can't "create signal" (they can only amplify existing signal with noise), you're not seeing an improvement.