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post #61 of 655 (permalink) Old 2005-08-18, 05:05 PM
jjc
 
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Signal Cancellation

Yaamon,

Have you think about the signal cancellation, will equal length cable guarantee the signal will in phase ?

Jason
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post #62 of 655 (permalink) Old 2005-08-18, 06:24 PM
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jjc as long as the cable from the baluns going to the splitter is the same length and the baluns connected in phase its basically the same as how they tied the 4228 together.

I can see why on hdtv primer the author mentioned the feed lines would radiate signal and by doing what I am should yield a stronger signal across the band.

They say the phase can be out 15% and it's not a problem.

Would be very nice if some had a meter, so I could test the signal from the 4228 antenna and compare it to what I am get after.

Too bad my channel master satellite signal meter 1005IFD dont read the same frequency.

CM4228/9521/7775;F.RmJvc70FH96/8300HDPvr/Dish 612;B.Rm LC52LE810UN/8642HD;Study LG50PK550/Xbox360;

Last edited by Yaamon; 2005-08-18 at 06:30 PM.
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post #63 of 655 (permalink) Old 2005-08-19, 03:32 PM
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Testing Stacked 4221 at the office through my window on ground floor.

I hooked up one 4221 and leaned it up against my coated office window I can only get cbs and pbs from Buffalo but the Toronto channels come in at full signals 10 out of 10 except Toronto One at 9 bars.

Pbs and Cbs was coming in at 6 to 7 bars.

Antenna is point south and is resting against the glass.

The window in my office has a tint in it.

Looking out my window where the antenna is pointed south there is a Monte Carlo Inn. Right across the street blocking my south view 2 1/2 story higher than where the antenna is pointed.

Its a 3 story motel and has a high peak roof. The antenna is mounted 5" off the floor.

When I had the radio shack antenna in my office same location the 15-1880 I think all I could get was cbc, cfto and city, cbc f.

Signal was only 5 to 6 bars.

Connected the splitter in reverse and the signal bar dropped down by one.

Connected back the other 4221 on the other side of the splitter that's mounted on the same pole on top of the other 4221, the signal went up 1 to 2 bars.

So the gain from the other antenna was more than the small loss from combining the signal with the splitter.

The antenna bow are spaced evenily. I wanted to see what difference in signal it would make if I lift the other antenna higher.

Well I lifted it 6" higher and the signal was the same.

If the weather hold up I will try and install the antenna tomorrow and test the sginal with one and then two.

CM4228/9521/7775;F.RmJvc70FH96/8300HDPvr/Dish 612;B.Rm LC52LE810UN/8642HD;Study LG50PK550/Xbox360;

Last edited by Yaamon; 2005-08-19 at 03:38 PM.
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post #64 of 655 (permalink) Old 2005-08-20, 07:14 PM
 
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4221

Yaamon, could you measure the distance between the bowties and the mesh?
That is the only measurement that I could not figured out from the pictures posted on the forum.

Thanks
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post #65 of 655 (permalink) Old 2005-08-20, 10:28 PM
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Telsat do you mean the distance between the bow and the mesh grill behind, its 4 1/4" ? Let me know if you need any more measurements.

Small update on the dual install.

Had to go to my niece birthay party by 1pm and started the install by 11:15am.

Got all the tools ready on my deck and dragged up the two antenna on the roof with a 5' extension pole from home depot with a 1.0"ID and a coupler after making several trips up and down the ladder by myself.

Tested the signal with my current setup and then removed the antenna and installed a single 4221. I seem to get the same signal as the 4228.

Nbc came in a little stronger pointing at the same position as I was before, guess from the wider coverage.

Then damm the coupler was too small the pipe on my existing tripod mount seems to be just a tiny bit bigger than 1 1/4" so I could not mount the other antenna on top.

But I did manage to moved the first 4221 all the way down the pole enough to get the lower part of the second antenna on the pole together.

Nbc and Fox both came in stronger but as soon as I installed back the pre amp the signal went down and lost some channels ?

Does the splitter that I used to combine the signals need to have a pass through ?

I did not have any more time to test and play around so I installed back my 4228. I had my 11 year old son in the bedroom checking the signal while I was on the roof with my cell.

I will try and go to home depot tomorrow and see if there is a coupler to connect the pole I bought to what I have. I having family over for dinner so not sure if I have time to play around with the antenna.

Finally installed the ground wire on the lower part of the mass, and its been through several thunder storms.

The coax line was always grounded with a block and used a copper rod.

CM4228/9521/7775;F.RmJvc70FH96/8300HDPvr/Dish 612;B.Rm LC52LE810UN/8642HD;Study LG50PK550/Xbox360;
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post #66 of 655 (permalink) Old 2005-08-20, 10:41 PM
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Iam selling the Channel master antenna and stock the 4228 and 4221.

Located in Markham.
Rogers/Satellite Specialty Services
8920 Woodbine Avenue
Markham,
905470 9604 Ext 230
Open Monday to Friday 9am to 5pm.

3 lights north of highway 7 and south of 16th Avenue.
On the west side of Woodbine.

CM4228/9521/7775;F.RmJvc70FH96/8300HDPvr/Dish 612;B.Rm LC52LE810UN/8642HD;Study LG50PK550/Xbox360;
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post #67 of 655 (permalink) Old 2005-08-22, 03:06 PM
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Final results, no dual 4221 setup sorry guys.

I ended up using a cm4228 and cm4221 together.

Did not have time to reinstall the dual 4221 as I took time off work this morning.

Asked my coworker what combiner did he use and he used a Channel Plus 2532. So this is what I used. He also experienced the same problem when using a regular splitter and then into the preamp.



Removed the center 5' pole and went to home depot and bought a new one 10' and drilled the hole in the base where a support screw goes. Cut off 1' so I ended up with a 9' pole.

I installed and pointed the cm4228 for max signal from NBC and this was past south on my compass going towards east.

I then setup the 4221 for max signal on FOX the antenna ended up pointing almost dead south.

All Toronto are are max signal expect Toronto One at 7 bars. I wanted Fox to be the strongest and if I setup Toronto 1 at 10bars, Fox would drop to 6 to 7 bars.





I then combined the signals, and hooked it up to the preamp. There was now signal on the tv and all the channels are at max, but Fox dropped to half 5 out of 10.

Damm I figured it must be a phase problem, but then again both feed to the combiner was equal length.

I figured the signal is hitting one of the antenna before the other creating a phase shift. I then deceide to rotate the 4221 and the signal strength came back up.

I'am a happy camper now.

I will be going away this weekend for a week, and when I come back I might finish the experiment at my office, as I will be installing a 4221 there and the roof is flat I dont have to worry about falling off my roof or the ladder.

CM4228/9521/7775;F.RmJvc70FH96/8300HDPvr/Dish 612;B.Rm LC52LE810UN/8642HD;Study LG50PK550/Xbox360;

Last edited by Yaamon; 2005-08-22 at 03:26 PM.
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post #68 of 655 (permalink) Old 2005-08-22, 06:27 PM
 
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Yaamon you can reverse the phase 180 by reversing one of the leads from the matching transformer on one of the antennas.

Attic CM 4248 at Buffalo,M4 at Buffalo.VHF yagis at Toronto .
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post #69 of 655 (permalink) Old 2005-08-22, 06:58 PM
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Rob you know what when I had it setup at the office I did it and it made no difference to the signal this was using two 4221.

I don't think that I'am going back up on the roof for now not unless there is a good reason to.

When I hooked it up on my roof I did not bother to check, I wonder if it does make a difference with different antenna's why with Fox I had to repoint the antenna ?

CM4228/9521/7775;F.RmJvc70FH96/8300HDPvr/Dish 612;B.Rm LC52LE810UN/8642HD;Study LG50PK550/Xbox360;

Last edited by Yaamon; 2005-08-22 at 08:36 PM.
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post #70 of 655 (permalink) Old 2005-08-22, 11:23 PM
 
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Quote:
Originally Posted by Yaamon
I ended up using a cm4228 and cm4221 together.
Thanks for the update, Yaamon.

What you did makes a lot of sense, the best of both worlds. Use the 4228 for the most difficult station and the 4221 for the rest.

Did any of the Rochester stations come in? Did your friend manage to get the Rochester stations back after they faded out?

Last edited by weblurker; 2005-08-23 at 12:02 AM.
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post #71 of 655 (permalink) Old 2005-08-23, 12:20 AM
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No Im afraid that the Rochester channels did not come in today or have for the past few days.

My friend also lost the Rochester channels. But he is still pulling in Nbc and Fox all in at 10 out of 10 with all the other Buffalo and Toronto channels as of this evening.

His Toronto 1 comes in at 7 bars.

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post #72 of 655 (permalink) Old 2005-08-24, 09:54 AM
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Thanks for the pics. Now your antenna looks just like mine, except i have the 4228 on top.
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post #73 of 655 (permalink) Old 2005-08-24, 10:04 AM
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Ohh, Tom question when you gad setup the dual antenna did you point each antenna for max signal and when you connected it to the combiner/splitter/pre amp did you notice any drop in signal and had to repoint of of the antenna ?

I had that problem with Fox what I had to move the 4221 more east. All other was ax max signal but for some reason Fox dropped in half till I repointed it.

Thanks

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post #74 of 655 (permalink) Old 2005-08-24, 01:54 PM
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Quote:
Originally Posted by Yaamon
...did you point each antenna for max signal and when you connected it to the combiner/splitter/pre amp did you notice any drop in signal and had to repoint of of the antenna?
If we superimpose the top-down graphs showing the receiving apertures of the CM4221 and CM4228 and start to turn one of the antennas we find that strong lobes and weak zones from the other antenna may be overlapping or working against it. This would of course be true if the baluns are out of phase but you've already said that you figure that's not the case, and your results seem to prove that, so I think there may be something a bit more subtle happening. My guess is that you had to turn the antenna farther than you thought in order to get a good signal because an overlap or convergence in the lobe or null patterns was causing problems at that specific azimuth. I welcome anyones' thoughts on whether nulls and lobes can weaken eachother in this kind of scenario when the baluns are in phase.
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post #75 of 655 (permalink) Old 2005-08-25, 09:22 AM
 
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I also recomend the 4228a. I see the (US) price has dropped $10. It can be had for $40 (US).
15 lbs isn't heavy for an antenna.
I'm not a fan of amps, especially outdoor where yoiu can't get to them. Better yet in a attic (or crawl space) where it is out of the weather and where you can add traps and/or filters for problem local transmitters that might overload the amp.
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