Ah....i must be having a brain short!

thanks...I have a feeling Stampeder may move all these posts to amplifiers...

just so im clear,

they are both made by channel master
they are same quality
they are different models
they have the same SPECS
yet there may be other differences, including exterior usage...

so in real terms it means I have to get the specs from Rabel's CM model...

so far the models I found show either of the folllowing on the amp itself:

1. PCT-CM-3410
2. PCT-MA2-M
3. Channel Master CM-3410

Channel Master site says:

Weather sealed housings for superior corrosion performance


PCT site says:

Operating temperature :
-40 to 60° C (-40 to 140° F)

Housing:
Cast aluminum with powder coating with weather seal

Yuprules,

the Raybel says he's quite sure its OK outside, based on the look of the seal....they only mention PCT MA2-M on the amp itself...

If any of the FM stations in Ottawa are using RDS the sparkling effect might be caused by that data stream... just a guess since I've never come across it before.
Now there's a thought -- yes, most of our locals do have RDS info tagged onto their broadcasts.

-ml

I want to have ABC station on my TV and I purchased a per-amp CM-7777. My problem is the 3.1 CBS station from Burlington, VT is very strong and is saturating my CM-7777.

I did the next test:
-Without CM-7777 just with my CM 8bay antenna the channel 3.1 is 82% on my Sony TV.
-Adding the CM-7777 to the antenna will make 3.1 level goes to about 32% (ant all the other channel are lost).
-Adding an extra attenuator (about 7db) BEFORE CM-7777 (and after antenna) will make 3.1 level back to 70% and all the other channels are also back.
So, looks like my CM-7777 is saturated by channel 3.1. I purchased this pre-amp CM-7777 in order to bust the channels 44.1FOX and 22.1ABC that are transmitting from the same city as channel 3.1.

Any idea on how to equalize the power stations level (my location is in LAVAL)?


Thank you,

Your tuner could be an influence. I used the CM 7778 on my Samsung TV and no overload issues- I have some signals 2.5 miles from my house. I tested this pre-amp on my LG TV- and... major overload- many stations just didn't come in that came in before (without the pre-amp).

Thank you for info.
Just to clarify, what do you mean by "major overload"?

About the TV; I don't believe is the TV because I did the next test:
-When I have the attenuator between Antenna and CM-7777 I have most of the channels.
-When I move the same attenuator right before the TV, I have just one channel 3.1 at about 30% (without CM-7777 the channel 3.1 was at ~ 85%).

FYI, My CM-7777 is not installed close to the antenna, is installed after about 30ft coax cable (I don't believe this is a problem).

Maybe I will try to change my CM-7777 with CM-7778 (or HDP-269). The CM7778 has less gain (and the noise figure is higher - so, less sensible).

I will try also to move away the antenna from the strong stations.

You might try de-aiming your antenna, provided CBS is at a different compass point then your other stations. You might be able to get preferential attenuation that way - sacrifice some gain on weak stations to get greater decrease on CBS.

I have much the same situation, one close LOS station vastly stronger than more distant 1-edge stations. Luckily for me the strong station is about 86º off from the weak ones giving me maximum benefit from a directional antenna. Even so, I went with a more overload-resistant pre-amp (AP-8700).

You have not described how your equipment is set up, so I will try guessing here: the pre-amp is not going to be useful unless you install it within a metre or two of the antenna.

Cheers

balm: keep me posted on you PCT amp purchase and performance, I have seen they have the PCT 3410 at Raybel, but did not see a price sticker. The noise dB is around 3.7dB I think so it is pretty noisy and not much better than those elcheapo single input/output 5db amps that I am currently using.

mlord :

I believe that to be true. I have attempted several time to use pre-amp as a distribution aid for extra long inside runs. It never seems to do anything beneficial. For some reason, pre-amps must be specifically designed to be near the original signal source. My thought has always been that there could be some sort of a noise cancelling filter within a pre-amp that kills the in-line signal.
__________________________

Jtag :

Sometimes if you get less signal after installing a pre-amp, it could be because the inserted power is not getting up through your cable to the Mast mounted pre-amp. Check to make sure your getting 18-22 volts to the end of the coax at the pre-amp. Without the inserted power, a pre-amp circuitry becomes a roadblock to the antenna's signal.

EdT,

yes no problem, it is priced at that of HD,or RS avearge distro amp...

i'm hesitating on buying, Raybel wont take that back if it doesnt do what I want....

I tried the HD's RECOTON distro amp....was a disaster...but whats great I simply return it!

BTW, not to be picky, but the PCT is 2.7 noise! Also note that a CM preamp has 2.2 noise on UHF!

My CM-7777 is not installed close to the antenna, is installed after about 30ft coax cable (I don't believe this is a problem).Well it actually is a problem, as mlord and ota_canuck have said. Get that preamp right up there with the antenna so that we can make some progress with debugging your system, and make sure all connections between it and the preamp's power injector allow DC Power Pass. :)

You have not described how your equipment is set up, so I will try guessing here: the pre-amp is not going to be useful unless you install it within a metre or two of the antenna.

Cheers

Here is my set up:
On the roof I have a CM-4228HD antenna.
Next, about 30ft coax cable RG6 (outside).
Next, CM-7777 preamp (outside).
Next, another 30ft coax cable RG59 (inside).
Before TV on coax cable I have the power box for the preamp.

What do you mean about "pre-amp is not going to be useful"? The preamp is not working at all or the preamp will work but not at the maximum parameters.
In my situation the preamp is not working at all after 30ft RG6 cable.
To be more clear, I called "not working at all" but relay the preamp is working, the 3.1 is at 30% (from 80% without preamp) level and if I disconnect power the 3.1 channel is lost completely (0%).
FYI, the preamp unit is OK (I tried two units and both are the same). So, there are two possibility: 1- the preamp is saturated. 2- the preamp is NOT working after 30ft coax cable.
I also send an e-mail to Channel Master and asked if the preamp will work after 30ft coax cable and what is the MAXIMUM TOTAL INPUT# (MICROVOLTS) for CM-7777 (just to compare with AP-8700).

Your tuner could be an influence. I used the CM 7778 on my Samsung TV and no overload issues- I have some signals 2.5 miles from my house. I tested this pre-amp on my LG TV- and... major overload- many stations just didn't come in that came in before (without the pre-amp).


You mentioned that you have a TV station 2.5miles from your house and your CM7778 is not saturated. Did you have also your antenna pointing on direction of this TV station?

I have a TV tower 2.5 miles from my house (not the actual station/studio).

Yes, I can have my 4228HD pointed directly at the close tower and no overload on my Samsung.

In agreement with others- you should try to have your pre-amp less than 3 feet from your antenna- then your longest piece of coax (30 feet?), then power injector, then short coax (5 feet) to TV/tuner. Also, the pre-amps first deed is to overcome signal loss from long coax lengths (e.g., 75 feet), joiners, etc., 30 feet is not very long. Maybe a lower powered amp might work, but again it could be your tuner. Lastly, it could be a defective pre-amp, I returned a 7777 that did nothing for me, the 7778 was better, and it was an older model. Many things could be going on, that will need further troubleshooting, experimenting, good luck.

2- the preamp is NOT working after 30ft coax cable.After 30ft of coax, you have some line loss, you may have also gained some line noise at that point. The 7777 is a powerful amp, but it's also a noisy amp and it will amplify the 30ft in-line noise which may be what is killing the tuner's ability to make something out of the signal. The signal reading you're seeing is actually only a measure of the useful readable clusters of information that your tuner can use, it's not about the strength of the total signal.

You may actually have multiple problems happening all at once, so you need to start over with the pre-amp right up near the antenna to at least eliminate that problem.

Well I have exactly the same problem.
CM4221HD on the roof, about 35' of coax, currently with no preamp - three weakest channels (FOX, NBC, CBS) come and go.

I had a AP4700 preamp at the antenna but when it was powered it was cancelling most of my channels (except the strongest ones). When power was disconnected I was getting most of the channels (without the weakest ones).

Eventually preamp was removed altogether and now reception is more or less OK. (see above).

I also tried distribution amp in place of AP4700 and had the same effect - 0 signal strength on almost all channels.

Interesting that AP4700 worked perfectly increasing signal strength when my CM4221HD was in the second floor bedroom, but started giving me problems when antenna was installed on the roof.


I still like to use a preamp to increase strength on weakest channels since I have dual tuner which causes some signal loss.

Hi Jtag and welcome to the forum!

While it's true that having 30 ft of RG6 before your pre-amp is not ideal, I don't think this is what's giving you problems.

Since you're in Laval, you're due North of the Mt. Royal transmitters. To aim at Mt. Mansfield, you must aim mostly South, also towards Mt. Royal. There's a couple of 1 MW analog transmitters there. If you're seeing overload, it's probably from that and not from WCAX.

So how to fix this problem? Well it depends on a few things. First, what is the degree deviation between Mt. Mansfield and Mt. Royal? You could get a more directional antenna (i.e. UHF yagi) and which would have lower gain on Mt. Royal if it's far enough off axis. But this has a better chance of working if there's maybe 20+ degress between the two.

You could consider getting notch filters for UHF 17 and 35. These will block the signal from the two megawatt stations. But those will be expensive (maybe $100 each from TinLee) and will be useless in two years.

You could also just wait until August 2011 when they pull the plug on those analog stations and they get replaced by lower power digital ones. Though I think CBMT-DT will be close to 1MW. I forget.

Last, you could consider all of the above with a pre-amp with higher input capacity, such as the HDP 269.

Putting a 7 dB filter adds 7 dB of loss before your pre-amp, you probably have another 1 dB of line loss, 2 dB balun loss, and 2 dB noise on the CM 7777. So you're killing 12 dB of signal before it's amped. A straight run of coax will surely have less loss than that. Sometimes one is better off without a preamp too! But only trial and error will tell. And that's what you're doing.

STL

goforit - how strong are those local stations (is there more than one?) and are you using a preamp? It actually takes 2 strong stations to start causing problems at a preamp (IMD is the result of mixing products between two strong sources at the input of an amp). So if there's just one strong channel, you might be ok. In Toronto, there are several >1MW analog transmitters that even at 30++ miles out could easily overload a CM7777 if Buffalo and Toronto are directionally in-line and you're using a high-gain antenna.

gg22 and jtag - it sounds like your problem is due possibly to preamp overload, not tuner overload. A classic sign of preamp overload is that your strong stations stay ok but the weak stations disappear or get worse. That's because when you overload the amp you generate a lot of additional noise, and which stations are most susceptible to noise? The weakest ones with the lowest signal-to-noise ratios. Aside from additional attentuation (which might just make the preamp useless anyways from the point of view that it won't be very effective at minimizing the system noise figure), you may want to try a lower-gain/higher-maximum-input-level preamp like the HDP-269. If your weak stations are right in-line with your strong ones, that's one of your only reasonable options (unless you go with the pricey notch filters like STL mentioned).

Edit: just noticed that STL already mentioned the HDP-269 - my fault for not reading closely! :)

Tom