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post #91 of 2254 (permalink) Old 2010-06-26, 11:37 PM
 
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I have not EVER seen wwny even on nights when wwti comes in quite strong (60-80% tonight for example). I am going to try to raise my antenna another 5ft and maybe get a rotator for the antenna as well as the trips to the roof are getting old.

I am hoping WNYF will come in no trouble...as I said before WNPI is always on with plenty of signal and WCFE is no trouble on any night so long as I point the antenna in that direction. I get wwti about 40% of the time so far...when I do it works really well.

I have been using Peter Near's hack to get WMC to work for the digital stations, but I am having trouble getting guide data for the USA stations (tried his USGuide hack, but it doesn't see the mountain lake pbs). Any ideas?

Thanks.
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post #92 of 2254 (permalink) Old 2010-06-27, 01:11 AM
 
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Quote:
Originally Posted by mike infinity View Post
I am hoping WNYF will come in no trouble...as I said before WNPI is always on with plenty of signal and WCFE is no trouble on any night so long as I point the antenna in that direction. I get wwti about 40% of the time so far.
Mike, I think you are in a great position to get WNYF-LP (18/28.1; FOX-SD/CBS-HD), WNPI (23/18.x; PBSx3), WCFE (38/57.x; PBSx3) as well as all the locals. But WPBS (41/16.x; PBSx3; -20.3 dB Noise Margin), WWTI (21/50.x; -21.8 dB NM), and WWNY (7/7.x; CBS-HD/FOX-SD; -6.3 dB NM but VHF-HI) will be big challenges to get more than intermittently, unfortunately. Recent weather conditions have allowed much better signal propagation than normal. (I've been picking up channel 35/28.1 FOX from Watertown occasionally over the past few weeks -- definitely abnormal.)

Back to that CM-7777 preamp: Please check out this chart (hope this link works -- if not, see the first post in the Signal Amplifiers thread):
http://www.digitalhome.ca/forum/atta...9&d=1272650415

The CM-7777 maximum input for two strong VHF channels is -29.8 dBm, -35.8 for UHF. (Reduce by 3.6 dB if 3 strong signals, 5 dB for 4, 7 dB for 6, etc.) Your tvfool report shows channel 4, 9, 13, and 6 all above the VHF levels, and several of the UHF channels also coming in hot. Once the preamp is driven into overload, results will become unreliable and unpredictable.

Here are some suggestions, and I hope the forum experts will chime in with feedback and criticisms:

a) Depending on the cable length from your antenna to your splitter/tuners, consider eliminating the CM-7777 completely.

b) If you are mostly interested right now in just the digital channels, I'd suggest that you get a UVSJ and a 75 ohm termination. Aim the 4228 between South Colton (151 degrees) and Plattsburg (122 degrees). Connect the 4228 to the UHF port on the UVSJ, and the 75 ohm termination to the VHF port, and connect the joiner output to the CM-7777 input. This should help attenuate the hot VHF signals from CF.

c) If you also really want the analog VHF channels, get a low-gain (simple dipole?) VHF antenna, and run a separate cable for it down to where you have your splitter/tuners. Connect this to the VHF input of another UVSJ, the tv-side feed from the CM-7777's power supply to the UHF input, and this joiner output to your splitter/tuner input.

A long post, but I'm really hoping to get some feedback/discussion on these suggestions.

Last edited by ashtonp; 2010-06-27 at 01:46 AM. Reason: added noise margin comments
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post #93 of 2254 (permalink) Old 2010-06-28, 03:43 PM
 
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About option b) Since Mike has a CM-7777, instead of the UVSJ to cut off the strong VHF, I assume he could also just reconfigure the CM7777 for "separate" VHF and UHF inputs instead of "combined", and keep the current cable connection to the "UHF/Combined" and this would do the same job ? Just plug the 75ohm termination to the VHF input of the CM-7777 ?
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post #94 of 2254 (permalink) Old 2010-06-28, 03:47 PM
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flavoie: That is certainly an option!

Roof-top mounted Antennas Direct DB8e & C5, Channel Master 7777 preamp, Siemens surge protection. TiVo Roamio DVR
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post #95 of 2254 (permalink) Old 2010-06-28, 06:34 PM
 
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another idea for b)
channel 4, VHF analog, is the strongest channel by far coming in from CF in your tvfool.

Use an HLSJ to filter it out along with the VHF-LO channels and keep the CM7777 in combined input.
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post #96 of 2254 (permalink) Old 2010-06-28, 07:21 PM
 
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Quote:
Originally Posted by roger1818 View Post
To be honest though it is tough to make recommendations right now as everything will be changing in a little over a year and we don't know for sure what will be happening then.
Thanks for this feedback
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post #97 of 2254 (permalink) Old 2010-06-29, 12:18 AM
 
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A couple of follow-up comments on my earlier suggestions for Mike:

Yes, the CM-7777 does have a separate UHF input available, and I suggest that you use this. However, I think that your situation calls for very aggressive attenuation of some of the VHF signals, and I'm not sure what the effectiveness of the CM-7777's internal bandpass (or hi-pass?) filter is on this input. Posts in other threads have indicated that a good UVSJ can provide a very effective filter for VHF signals, so this is what I've suggested.

Also, although Ch 4's power level immediately sticks out (-14.4 dBm), based on charts I've seen for its predecessor 4228, the 4228HD's gain on VHF-lo may be quite poor (to negative). However, its gain on channels 9, 11, and 13 could be 4-6 dBd, depending on antenna orientation, so all of these signals (4, 9, 11, 13) must be considered for CM-7777 overload.

Golly, this gets complicated
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post #98 of 2254 (permalink) Old 2010-06-29, 12:20 AM
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Quote:
I think that your situation calls for very aggressive attenuation of some of the VHF signals, and I'm not sure what the effectiveness of the CM-7777's internal bandpass (or hi-pass?) filter is on this input. Posts in other threads have indicated that a good UVSJ can provide a very effective filter for VHF signals
Yep, there are some great examples of that in here:

Splitters, Attenuators, Filters, Diplexers, Other Signal Gear



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post #99 of 2254 (permalink) Old 2010-06-29, 09:48 AM
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Quote:
Originally Posted by ashtonp View Post
I'm not sure what the effectiveness of the CM-7777's internal bandpass (or hi-pass?) filter is on this input. Posts in other threads have indicated that a good UVSJ can provide a very effective filter for VHF signals, so this is what I've suggested.
I haven't seen the specs, but I would expect the CM7777 would be as if not more effective at filtering out VHF than the UVSJ as I believe it has filters on both the input and output stages (one of the nice things about the CM7777 is it has separate amplifiers for VHF and UHF to eliminate harmonic distortions of VHF causing interference on UHF so it needs filters on the input to ensure it is only amplifying signals from the desired band and filters on the output to effectively combine the bands together).

Having said that, if you are only wanting to amplify UHF, you would be better off using a dedicated UHF amp that will either block or bypass VHF (depending on whether you are using a separate VHF antenna or not). If you do decide to stick with the CM7777, be sure and put a 75 ohm terminator cap on the VHF input to ensure no signal leaks in.
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post #100 of 2254 (permalink) Old 2010-06-29, 10:02 AM
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Quote:
Originally Posted by ashtonp View Post
Connect the 4228 to the UHF port on the UVSJ, and the 75 ohm termination to the VHF port, and connect the joiner output to the CM-7777 input.
If you do this, I higly reccomend connecting the UVSJ the other way around with the antenna connected to the combined port and the UHF port to the CM7777 to ensure no signal leaks from the VHF port to the amp. I would still terminate the VHF port though.

Quote:
run a separate cable for it down to where you have your splitter/tuners. Connect this to the VHF input of another UVSJ, the tv-side feed from the CM-7777's power supply to the UHF input, and this joiner output to your splitter/tuner input.
To avoid the need for a second downlead, you can get a band combiner (such as the EU385-CF) that has power pass on the UHF port, allowing you to put it between your pre-amp and power injector.
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post #101 of 2254 (permalink) Old 2010-06-29, 01:47 PM
 
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Quote:
Originally Posted by roger1818 View Post
If you do this, I higly reccomend connecting the UVSJ the other way around with the antenna connected to the combined port and the UHF port to the CM7777 to ensure no signal leaks from the VHF port to the amp. I would still terminate the VHF port though.
Argh! Thanks for catching this, Roger! That is what I meant to type, but got so focused on being clear about the port identification (since it's being connected in "splitter" mode), that I got them backwards.
Quote:
Originally Posted by roger1818 View Post
To avoid the need for a second downlead, you can get a band combiner (such as the EU385-CF) that has power pass on the UHF port, allowing you to put it between your pre-amp and power injector.
Yes, definitely something to consider, and would simplify grounding.

Last edited by ashtonp; 2010-06-29 at 02:04 PM. Reason: add "splitter" mode comment
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post #102 of 2254 (permalink) Old 2010-06-29, 07:58 PM
 
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I am bringing this tower over from TO from our house that we sold to Ottawa ( orleans area ). I am guessing this will help with signal gain?



Also....am I able to attach a 1.2m dish on a motor to it to get true FTA, or am I just better off with the dish on the ground in the backyard? I am buying a VHF cm 3020 also to go with my cm4228 that I already have in the pic

cheers
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post #103 of 2254 (permalink) Old 2010-06-30, 10:17 AM
 
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Hey Mick,

I thought you wanted a VHF only antenna up top. That would combine easier with your 4228.

I would mount your dish low on the tower depending on the tower type you have, or you could eave mount it like half the houses in Orleans.

Let me know when your tower goes up, I would like to watch (or help).
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post #104 of 2254 (permalink) Old 2010-06-30, 12:38 PM
 
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Yes I want the vhf antenna that have just bought online, to be coupled with the cm4228 you see in the pic. The pic is from our house in the GTA, I am trying to create the same look here in Ottawa

Looks like the city by-laws here are going to cause me to install the tower somewhere else in the yard, unlike with the location in the pic

I just wanted to make sure too that a 1.2m dish won't be too heavy for sure a tower and that it will be able to move with a motor
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post #105 of 2254 (permalink) Old 2010-07-09, 05:10 PM
 
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This thread has been quiet for a while now, what is going on in Ottawa Orleans area?
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