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Old 2009-10-12, 10:29 PM   #1
goforit
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Exclamation 4228HD for Highest UHF channels: avoid unless hacked

Word needs to get out on the 4228HD being terrible for high UHF. It seems that unexperienced/rookie DHC members are getting the 4228HD, thinking that it is big and powerful, but then are left scratching their head when they can't get the high UHF channels. Granted, it seems that this is specific to the low powered digital stations off the CN tower (Global and OMNI digital), but when the gain chart of the 4228HD is examined, a severe drop off is noticed in the high UHF range. So, it you are trying to get high UHF channels stay away from the 4228HD, there are much better alternatives like the 91XG.
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Old 2009-10-12, 11:17 PM   #2
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The U.S. UHF channels now end at 51. From 52 to 69 will soon be history here, in a couple of years. Those frequencies are being alocated for other uses, like police and firefighters and civil defense, stateside. This is why the older 4228's are almost obsolete.
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Old 2009-10-12, 11:43 PM   #3
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Newer antennas are most likely geared for the US market. That means mainly channels 7 to 51. Some US markets still have VHF Lo stations but not as many as there once were. No US markets have stations above UHF 51.
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Old 2009-10-13, 02:34 AM   #4
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I have a cell tower not 3km away plus other sources of strong RF that I would like my current antenna not to receive and be amplified to heck, so the sooner antenna mfrs roll out new 14-51 designs the better. I'd love for AD to make a 'new U.S. UHF spectrum' designed 91-XG yagi.
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Old 2009-10-13, 11:59 AM   #5
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Exclamation Hey...not so fast!

No need to worry: The 4228hd high range gain is fine with the simple two balun mod.

I can overload an AP 8700 by pointing a single 4228hd directly at TO from Oshawa.... So I have to use the side lobe, and that leaves the main lobe for Buffalo: perfect for people in my area. Also, my 4221 (original) has yet to beat my 4228hd modified when pointed directly at TO with the high channels.

Cheers!
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Old 2009-10-13, 12:40 PM   #6
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Quote:
I have a cell tower not 3km away plus other sources of strong RF that I would like my current antenna not to receive and be amplified to heck,
A better solution would be to install a low pass or notch filter to eliminate the strong signals. It will work much better than antenna design to prevent overloading.
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Old 2009-10-13, 01:55 PM   #7
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Quote:
Originally Posted by Lineloss View Post
No need to worry: The 4228hd high range gain is fine with the simple two balun mod.

I can overload an AP 8700 by pointing a single 4228hd directly at TO from Oshawa.... So I have to use the side lobe, and that leaves the main lobe for Buffalo: perfect for people in my area. Also, my 4221 (original) has yet to beat my 4228hd modified when pointed directly at TO with the high channels.

Cheers!
Sounds good.

How's this?

For high UHF, avoid the 4228HD unless hacked?
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Old 2009-10-13, 04:28 PM   #8
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Smile A friendly opinion!

goforit,

Quote:
For high UHF, avoid the 4228HD unless hacked
That is more accurate however I still think the statement can be misleading to a new comer and here is why:

Please remember there is a best antenna and amp for every situation. Saying don't use this antenna can be just as confusing as us telling new guys they must have this antenna and that amp. I agree with the point your trying to make because "use what worked for me" and "this has the best spec" (purposely not plural) seems to be a major problem here considering the largest variables are your antenna location and it's surroundings. The best thing we can do is report facts as accurately as possible, and try to identify the characteristics of a device through careful test methods. These characteristics can then be used to someones advantage....with assistance from members with allot of practical experience and/or technical knowledge.

For a while now I've been thinking of starting a test method/standards post and I have also been thinking of asking the moderators to start some type of section where, we post individual devices like the 4228hd: Once one person posts a device, we can start compiling specific info, characteristics, specs test results, limitations geared only to that device etc... Now when a new person does a search in this section they get a fair assessment and understanding of the only that product and how it may fit with their situation.

Cheers!
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Old 2009-10-13, 05:12 PM   #9
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Sounds good.

I guess it might be a little too strong to say, "don't use", but I have encountered several posts where a new comer complains the 4228HD doesn't work. Also, it should be noted that the antenna chart references the 4228HD as the hacked version, and newcomers who want the quick answer might miss this and think, "wow, this is a big antenna, it must be good", but we realize that bigger is not always better. At a basic level (without hacking) the AD DB-8 and the 91 XG are much better than the unhacked 4228HD, especially at high UHF, but for those who already have a 4228HD0 help is here (ref. Lineloss) to make it a top-dog!
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Old 2009-10-16, 01:30 PM   #10
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I've adjusted the title based on the discussions... it is a fine antenna for almost all UHF channels except for the highest UHF channels. The stock CM4228HD isn't so hot on those, so doing the hardware hacks is essential.
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Old 2009-10-16, 02:10 PM   #11
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I think this is an important thread especially for those trying to get high UHF (i.e., > RF 60.1), like off the CN tower in Toronto- OMNI-1(64.1), Global (65.1), SUN (66.1) , maybe CITY (53.1), and also WNYO (49.1).

Cheers!
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Old 2009-10-16, 03:34 PM   #12
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Quote:
Originally Posted by goforit View Post
I think this is an important thread especially for those trying to get high UHF (i.e., > RF 60.1), like off the CN tower in Toronto- OMNI-1(64.1), Global (65.1), SUN (66.1) , maybe CITY (53.1), and also WNYO (49.1).

Cheers!
Totally agree, here. These are the channels I am having great difficulty with my virgin CM4228HD. Don't think I'll find my way up on the roof until the spring though. Just too busy.

Any chance the signals will be improved after 2011?

Larry
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Old 2009-10-16, 03:44 PM   #13
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A few things will/could happen come 2011: analog shuts down, digital stations increase power, re-allocation of digital channels (e.g., Global move from 65.1 to 41.1).
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Old 2009-10-16, 07:45 PM   #14
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Default High UHF Hack is possible

It is possible to do a hardware hack to the CM4228HD to shift its frequency response upwards in the UHF spectrum by cutting the bowtie elements about an inch shorter, but before trying it you need to consider 2 important things:
  1. it is a one way process (you won't be able to put it back the original way again)
  2. before you make any cuts you need to check with mclapp and others about the ideal bowtie length for the High UHF channels you desire
  3. you don't get something for nothing, so if you have low UHF channels that are weak you may lose them after this hack
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Old 2009-10-16, 08:35 PM   #15
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Default Reversible Hack?

Does anyone have a link to an easy to follow hack procedure for the 4228hd? One that is easily reversible. I don't NEED to get all the channels available but if there's something to try that I can back out of with out needing to buy an new antenna, I'll try it.

Larry
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