I'm looking for advice on a preamplifier.

I am located in North York, Young and Sheppard area.
I have a CM4228HD mounted to the chimney, I can get most of the Buffalo channels, but not ION. I added the CM7777 preamp. This made things worst. I'm guessing the amp is overloaded with the signals from CN Tower. I know I can try using attenuators since that will attenuate the weak signals. But I would prefer to use a different preamp that would have lower gain and not get overloaded. So I'm looking for recommendations.

- Preamp overload from CN TWR as you suggest, creating a mess towards your TV. Get rid or preamp, or put the CN TWR into a null on the antenna.
- TV tuner overload. More likely as your hot local signals overload the receiver from seeing the weak Buffalo stations. Add a 4-way splitter or attenuator to drop the signal strength enough that your tuner is happy.
- From your Yonge and Sheppard location, you have to aim THRU the CN TWR to see Buffalo. Hence the overload. If your location allows, try and aim at the distant (weak) stations, while keeping the CN TWR off-centre. This is geometry that may or may not be friendly to your exact location, trying to put the CN TWR into a minor null off the main lobe if you can aim directly at ION. Too much off-centre and you make CN TWR unreliable due to multi-path.

Let us know how this works out.

I used the 7778 on my system (in Markham) and I'm just shy on the fringe of overloading. It's lower gain than the 7777. I know on an old Sony TV with a really sensitive tuner, I could receive bits of analog TVO by practically tuning in any channel. Plus there are several HD channels from the CN Tower I can pick up no matter where I aim the antenna (which is normally highly directional).

For what it's worth, the Channel Master preamps are some of the best at NOT overloading.

See a previous message on the pre-amp posting, you are getting overload and distortion from the VHF port (if the 7777) has one. Only use the UHF section and terminate the other. I am at Yonge & Hwy 7, pointing straight thru the CN Tower with another make of UHF pre-amp only, works fine.

One of the problems with Buffalo, is that none of the Transmitters are actually IN Buffalo:

WUTV (FOX), WNLO (The CW), WNED (PBS)  are on Grand Island,
WNYB (TCT) is in Jamestown,
WGRZ (NBC) is in South Wales,
WKBW (ABC), WIVB (CBS) are in Colden.
WNYO (My TV) is in Wyoming,
WPXJ (ION) is in Batavia,

If you look at these towns, most of them are near Buffalo, except Batavia which is almost half way between Buffalo and Rochester.  A highly directional antenna might have problems with picking up both Buffalo and Batavia.

I'm using the CM4228 (an 8 bow tie UHF antenna), I'm able to pick up all the Buffalo stations with the antenna pointed directly at ION except for ION and WNYB. This is why I was hopping a preamp would fix ION (I don't care for WNYB).

I'm assuming that a lower gain amp would be less likely to be overloaded. If this is correct, what would be a recommended pre amp?

The 7777 has a separate VHF and UHF inputs, currently they are combined. I will disable the combing and report on the results, very likely on the weekend.
Which preamp are you using?

Where can I find a terminator?

Every system setup is somewhat different with different results, I only use a reflector jagi UHF antenna (picks up VHF chn 5 & 9 nicely also) at my location with pre-amp and pick-up most Buffalo area channels, ION is VERY spotty. I also have blockage due to apartments to the south and Buffalo chn 4 and ION is a problem for me.

The amp (note the amp voltage supply is 12 volts NOT 18 like some others) I am using is:

from Antra: (http://www.partsforhdtv.com) which did not overload pointing straight through the CN Tower to Buffalo

HDTV Antenna Low Noise High Gain Pre-Amplifier Model: AT-PAU18
CAD $32.09

SPECIFICATIONS

Frequency Range UHF CH14-69/470-806MHz
Gain 28dB
Noise Figure 2.0dB
Power Supply 12VDC/100mA


Good luck, its all a trial and error game, from your location you should NOT be pointing at CN Tower to get Buffalo, should be at approx. 4 to 5 o'clock due south.

The 7778 is 16db VHF and 23db UHF, versus 23db VHF and 26db UHF on the 7777. So if you're using VHF, and that's overloading, the 7778 might be a better match. I know back when I first spec'd this out quite a few years ago, I specified the 7777 but the antenna guys recommended the 7778 for my area.

My best guess is that its not the 3 dB difference on the UHF section that would give him the problem, its the 7 dB on the VHF side. To offset a 3 dB difference WITHOUT buying another pre-amp, 10 feet of co-ax will do the job nicely, between antenna and the pre-amp.

One can drop a lot of $$ into this at this point, knowing full well that in a year or two with Toronto channels going full power, everything changes and the pre-amps all over the place will be overloaded.

Also a good chance we will loss chn 17 from Buffalo on rf chn 42 with Global on rf 41 at full power. A wait and see.

Has any thought been given that any overload may be due to the analog transmitters. When they are shut down in Aug. 2011 the problem may be gone. Yes, the digital transmitters will be increasing there power at the same date but it will be less than the analog transmitters.

The majority of Toronto channels' idea of "full power" is the rest of the world's idea of "low power". ;-)

That might be, CIII-TV Channel 41 analog, is sending out 732kw the eventual digital 41 will be 100kw, so interference with 40 and 42 should be less then current.  I think 17 is actually on 43, which means that 44 would be the one to interfere and it's not at full power yet.......

I separated the VHF and UHF inputs on the preamp, so now nothing is feeding VHF, I don't have a terminator so the VHF input is not terminated.
This has removed the overload, all the stations that worked before still work, but ION still does not work. When I tried splitters between the antenna and the preamp it made things worst for many station. Maybe with preamp I will be able to split the cable more, and all tuners should see the same signal since the first transistor is going to be the one in the preamp.