Channel Master OTA Gear & Antennas

[Yaamon]

Bruce you are lucky the antenna are made in the US and is alot cheaper than what we can buy them here for.

I had my brother mail order one but they charged him $20.00 shipping, he lives in FL.

He would have saved a little more $$ if his local dealers close to him stocked and sold the antenna's.

[stampeder]

Originally Posted by videobruce

15 lbs isn't heavy for an antenna.

That 15lb number is not correct, as we've discussed earlier in this forum. I wish CM would change their specs on their website:
http://www.digitalhomecanada.com/for...6&postcount=29

[Yaamon]

open6l oh did not realise that was the direction from where you are located.

I'am going to install a 4221 one at my office as this little antenna does a great job of pulling in the Buffalo channels with almost the same signal as the 4228.

The 4221 has a much wider coverage than the 4228 and you might have gotten those two channels better. But if those two are no bif deal then no worry.

[intrac]

Originally Posted by Yaamon

open6l oh did not realise that was the direction from where you are located.

I'am going to install a 4221 one at my office as this little antenna does a great job of pulling in the Buffalo channels with almost the same signal as the 4228.

The 4221 has a much wider coverage than the 4228 and you might have gotten those two channels better. But if those two are no bif deal then no worry.

Actually the 4221 is the 4-bay version of the 8-bay -- it doesn't have as much gain (actually 3 dB less which means about half power), and the beamwidth is almost identical to the 4228. See this page: http://www.hdtvprimer.com/ANTENNAS/comparing.html here: http://www.hdtvprimer.com/ANTENNAS/cm4221.html and here: http://www.hdtvprimer.com/ANTENNAS/cm4228.html

[jbracing24]

Originally Posted by Yaamon

I had my brother mail order one but they charged him $20.00 shipping, he lives in FL.

I ordered the 4228 online at Solid Signal .com for $40 US. It cost $15 US for ground shipping by UPS from Harrisburg PA to relatives south of Buffalo, serviced by delivery out of Batavia. Not very far indeed.
I imagine package size and gas prices are having a lot to do with it. The box it comes in is 42" by 42".

[Yaamon]

intrac what you said about the gain is true but from where I am located, there is no real signal difference between the antenna.

I have tested both, and have both of them currently installed.

My friend who lives a little more north of me has a 4221 that I lent him gets stronger signal than when I had just a 4228.

He just sold his new 4228.

From the diagram the 4221 has double the coverage of the 4228 and at a 30' window the 4228 is 12 to 15db down in signal.

The same 30' angle the 4221 is only 3 to 4 db down much better/stronger signal when receiving off angle signals.

[weblurker]

Originally Posted by intrac

Actually the 4221 is the 4-bay version of the 8-bay -- it doesn't have as much gain (actually 3 dB less which means about half power), and the beamwidth is almost identical to the 4228. See this page: http://www.hdtvprimer.com/ANTENNAS/comparing.html here: http://www.hdtvprimer.com/ANTENNAS/cm4221.html and here: http://www.hdtvprimer.com/ANTENNAS/cm4228.html

http://www.digitalhomecanada.com/for...ad.php?t=29068

Yaamon started the above thread about dual 4221s vs a single 4228. I think he included the same beamwidth diagrams that you included.

Unless I'm reading those graphs incorrectly, it's very clear the 4221 has a much wider coverage pattern than the 4228, not identical at all.

From the graphs, it appears that if the HDTV transmitters are 20 to 30 degrees off the 4228's main reception axis, the 4228 will produce a weaker signal than the 4221. The 4221's wider coverage would appear to more than offset the 3db main axis reception of the 4228 for those off axis stations.

I think Yaamon had it right, the 4228 may have been designed to be used with a rotator. If you're installing an antenna on a fixed mast, the 4221 may be the better choice, but it's heavily dependent on the geometry of the HDTV transmitters to the antenna.

If all the HDTV transmitters are within 20 degrees of the antenna, the 4228 is probably the better choice. If they're not, the 4221 might be better, except for those transmitters inside the 4228's best reception arc.

But in any case, I'd be very leery of discounting actual real life experience. When theory and graphs collide with reality, reality has a nasty tendency to win. :->

[stampeder]

We're continuing the excellent "Stacking Two 4221 vs One 4228" thread here in this thread to follow up on yaamon's and weblurker's posts below.

[videobruce]

Has anyone used a different matching network for this antenna? The one review I read about this commented on the matching network between the two halfs. He was concerned about pickup with the design the way it is.

[Oldfart]

My attic access is not large enough to accommodate a CM 4228, but I understand that it is possible to drill out some rivets and then fold the antenna, later replacing the rivets with nuts and bolts. Does anyone have any experience in this regard? Alternatively I can get two CM 4221s and hook them together side by side. What would be the best way to do this? I understand that intact reflector screen of the 4228 is what provides the high band VHF performance of the 4228, and I do not want to lose that.

[videobruce]

I wouldn't consider that option if it is one. How about an antenna that does fit as in a Yagi?

[stampeder]

Originally Posted by Oldfart

My attic access is not large enough to accommodate a CM 4228, but I understand that it is possible to drill out some rivets and then fold the antenna, later replacing the rivets with nuts and bolts. Does anyone have any experience in this regard?

I've never heard of that but I just went out and had a look at my CM4228 and I don't see why it wouldn't work, provided that all is returned to its previous state. The only thing I'd suggest is using stainless steel nuts, washers, and bolts so that the potential for rust from attic condensation is reduced while electrical conductivity is retained. If you try it please let us know how it goes!

[Oldfart]

As a matter of interest, here is a response I received from Holl_ands to a similar question I posed on the AVS Forum:

"It isn't so much the bigger reflector on the CM4228 that extends performance into the upper VHF band,
as it is the center feed structure: http://www.solidsignal.com/prod_dis...zoom=zoom#xview
Look at the individual view angles to see the detailed connection.

For UHF frequencies the "quarter-wavelength" feed structure combines the signals from eight individual
bowtie elements, with impedance matching as best as can be expected for a wideband antenna system.

However, for VHF frequencies the feed structure is only a small fraction of a wavelength,
so the entire antenna structure acts more like one very wide (and fat) center fed dipole
(with a reflector screen that is closer than optimum spacing).

If you simply use an RF Combiner (even a low loss Lindsay Stripline Combiner) to combine two CM4221's,
the VHF performance will be considerably worse than a CM4228"

[gordee78]

Hi all -- I am at Avenue and Lawrence area. Mostly detached homes and big trees area, and my CM-4228 is mounted on a 10ft pole in the backyard. I can get all of the toronto stations at around 80% strength (CTV almost 90%). I can receive ABC and CBS in buffalo at 30% strength, but WUTV(29-1) and NBC (2-1) are very weak and 60-70% of the time cannot get a picture at all. Would LNA preamp help in my case? Although there are a good number of houses in the way where I am, I know if I stand at Avenue Rd I can see the top half of the CN tower. Will a preamp saturate all my toronto stations? Are there low noise low-gain preamps (ie 8-12dB)? Everything I have seen is >20dB gain at UHF. Any suggestions (makes and model numbers, and where to buy) appreciated.

[Yaamon]

Hmm I'am not sure but if your view is obstructed and with your current setup with the 4228 I dont think a preamp will make that much of a difference.

If you are only using a 10' pole in the back yard, see if there is a way that you can position the antenna higher.

All you might need is maybe another 5 feet in height ? You have to clear the trees.

If your cable run is long then maybe, the pre amp will work.