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CM 4251 UHF Parabolic OR Stacked CM 4228 UHF, and will either help with VHF 13?

post #1 of 27
1/4/08 at 8:14am
Thread Starter 
I have read that the old Channel Master 4251 7' Parabolic UHF antenna was perhaps the best residential UHF antenna ever made. Unfortunately, they haven't been made since 2000 (I think I read the mold was lost or broken when Channel Master was sold?). However, I know of four that are currently installed in my area.

I have no idea if their owners would be willing to sell or not, but have considered stopping by their houses and asking. In some cases people now get their locals through satellite and no longer use the antenna, and further assume there's no market for them.

Which would likely be better, two stacked CM 4228 8-bay or the CM 4251 parabolic? Given the extra mounting considerations that come with installing the the large parabolic (on an existing 40' tower), is it worth the time, trouble, and potential extra expense to ask someone if they'll sell me their antenna and then get the thing mounted?

Also, one digital station I would really like to get is broadcasting from VHF 13, and indications are that it will remain there after February 2009. The UHF analog couterpart comes in fairly clearly on channel 27, but even with a really good CM VHF antenna, I'm having no luck getting the digital signal coming from the same tower (the info I have read says it's on the same tower) on 13.

Will a better UHF antenna help with VHF 13 at all? That may sound like a dumb question, I don't know, but I read somewhere (either here or dbstalk) that the UHF antenna can help with the upper VHF channels.

Finally, and this may very well enter into the decision-making process for me...Will antenna manufacturers be introducing anything comparable to the CM 4251 parabolic as February 2009 approaches? I know Wade makes parabolics, but I get the feeling they're heavier, more expensive, and intended for commercial purposes. Is that correct?

There are many people who have always gotten a reliable analog signal that will be left with no OTA reception when those analog signals are shut off. It would seem that the market for fringe OTA reception antennas will grow overnight when the analog is shut off and people are left with no OTA.

Sorry for such a long post, and thanks in advance for your input!
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post #2 of 27
1/4/08 at 8:37am
Read here - some of the info may be helpful to you.

http://www.digitalhome.ca/forum/showthread.php?t=41102
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post #3 of 27
1/4/08 at 8:52am
Quote:
Originally Posted by Jungle Jim View Post

I have read that the old Channel Master 4251 7' Parabolic UHF antenna was perhaps the best residential UHF antenna ever made.

Which would likely be better, two stacked CM 4228 8-bay or the CM 4251 parabolic? Given the extra mounting considerations that come with installing the the large parabolic (on an existing 40' tower), is it worth the time, trouble, and potential extra expense to ask someone if they'll sell me their antenna and then get the thing mounted?

Also, one digital station I would really like to get is broadcasting from VHF 13, and indications are that it will remain there after February 2009. .

Will a better UHF antenna help with VHF 13 at all?

Will antenna manufacturers be introducing anything comparable to the CM 4251 parabolic as February 2009 approaches? I know Wade makes parabolics, but I get the feeling they're heavier, more expensive, and intended for commercial purposes. Is that correct?

The CM 6' dish should outperform a pair of 4228's on UHF, but won't work very well on channel 13.

I doubt that antenna manufacturers will make anything better for UHF than the XG-91/4228.

The Wade Delhi 8' dish is about $ 2,500. I have one of these: http://www.kathrein-scala.com/catalog/PR-TV.pdf It works a couple db better than a 4228. Cost about $ 1,000.

I suspect that your channel 13 problem may be due to interference. Where are you located?
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post #4 of 27
1/4/08 at 9:10am
Quote:
Originally Posted by Tower Guy View Post

I suspect that your channel 13 problem may be due to interference. Where are you located?

I figured out that you are between Louisville and Lexington, KY. Both WBKO analog and WKYT digital are on channel 13.

You might be able to eliminate the interference with a pair of stacked Y10-7-13s. The proper stacking configuration would depend on your exact coordinates. GPS data would work, or go to www.topozone.com; navigate to your area, put the red X on your exact location, and cut and paste the URL here.
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post #5 of 27
1/4/08 at 10:52am
Thread Starter 
Thanks for the replies!

Quote:
Originally Posted by Tower Guy View Post

The CM 6' dish should outperform a pair of 4228's on UHF, but won't work very well on channel 13.

How much better would it do for UHF? Substantially or just some, or is there even a general answer to that question?

Quote:
Originally Posted by Tower Guy View Post

I figured out that you are between Louisville and Lexington, KY. Both WBKO analog and WKYT digital are on channel 13.

You might be able to eliminate the interference with a pair of stacked Y10-7-13s. The proper stacking configuration would depend on your exact coordinates. GPS data would work, or go to www.topozone.com; navigate to your area, put the red X on your exact location, and cut and paste the URL here.

Wow, you're good! I'm actually more in a straight line between WBKO 13 (analog) in Bowling Green and WKYT 13 (digital) in Lexington. And to make matters even more frustrating, this document indicates that both WBKO in Bowling Green and WKYT in Lexington will be using channel 13 after the February 2009 conversion. Will the FCC allow this to remain this way? I've been trying to understand the Tenative Channel Designation process. I'll check for some threads that address that after I post this reply.

As for my exact location, I'm hesistant to reveal it at this point for fear that someone might sneak in and snatch one of the CM parabolics. I'm saving this thread for future reference, though.
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post #6 of 27
1/4/08 at 12:11pm
It doesn't make much sense to size your UHF antenna to receive one VHF channel. Add a channel 13 Yagi to your UHF antenna using a UHF/VHF coupler and you should be in business.
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post #7 of 27
1/4/08 at 1:42pm
Thread Starter 
Quote:
Originally Posted by Joel Graffman View Post

It doesn't make much sense to size your UHF antenna to receive one VHF channel. Add a channel 13 Yagi to your UHF antenna using a UHF/VHF coupler and you should be in business.

I've been wanting to see if I can improve on the UHF reception I've been getting with the single 8-bay CM screen, and thought perhaps that I could kill two birds with one stone if it would have the added effect of improving reception on 13. From what I'm reading here, though, I need to also focus on improving my VHF antenna if I really want to help channel 13.

In addition to the CM 8-bay UHF I also have a VHF antenna. I'm not sure of the model number, but it was the best VHF antenna that Channel Master produced in 1995. Even with that, however, I'm not getting 13 for WKYT 27.1.

EDIT: When you say "channel 13 Yagi", does that mean that there are antennas designed to receive specifically that one channel?
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post #8 of 27
1/4/08 at 1:59pm
Antennacraft Y-10 will do the job for channel 13
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post #9 of 27
1/4/08 at 1:59pm
Quote:
Originally Posted by Jungle Jim View Post

EDIT: When you say "channel 13 Yagi", does that mean that there are antennas designed to receive specifically that one channel?

Yes - that is exactly what that means. www.solidsignal.com , www.starkelectronic.com should be able to help you
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post #10 of 27
1/4/08 at 2:08pm
Quote:
Originally Posted by Jungle Jim View Post

How much better would it do for UHF? Substantially or just some, or is there even a general answer to that question?

Wow, you're good! I'm actually more in a straight line between WBKO 13 (analog) in Bowling Green and WKYT 13 (digital) in Lexington. And to make matters even more frustrating, this document indicates that both WBKO in Bowling Green and WKYT in Lexington will be using channel 13 after the February 2009 conversion. Will the FCC allow this to remain this way? I've been trying to understand the Tenative Channel Designation process. I'll check for some threads that address that after I post this reply.

As for my exact location, I'm hesistant to reveal it at this point for fear that someone might sneak in and snatch one of the CM parabolics. I'm saving this thread for future reference, though.

The CM parabolic would outperform a single 4228 enough to make it worthwhile for UHF, but little better than two stacked 4228's.

I found your location my looking for other posts by Jungle Jim and discovered your posts in the local Kentucky threads.

You can PM your location to me, or just post a zip code. I have no need to steal a CM parabolic or a 40' tower, and wouldn't take something that didn't belong to me anyway.

Can you clearly see WBKO analog when you aim at it, or does WKYT-DT interfere with it? The FCC will allow both stations to be on the same channel in 2009, but WBKO's power should drop significantly.

If the two channel 13s are close to 180 degrees apart the best technique for reception is a pair of high band yagis using stagger stacking. With stagger stacking you place the two antennas above each other, but offset by 1/4 wavelength. When you add them together, one of the two antennas gets an extra 1/4 wavelength of coax. This makes the antennas in phase off the front, but out of phase off the back. It gains 3 db of signal from the desired station and drops the undesired station by as much as 20 db. If the signals from the two stations are similar in strength, this array could receive either of them just using your antenna rotor. The system would cost under $100.
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post #11 of 27
1/4/08 at 2:09pm
Thread Starter 
Quote:
Originally Posted by Tower Guy View Post

I figured out that you are between Louisville and Lexington, KY. Both WBKO analog and WKYT digital are on channel 13.

You might be able to eliminate the interference with a pair of stacked Y10-7-13s. The proper stacking configuration would depend on your exact coordinates. GPS data would work, or go to www.topozone.com; navigate to your area, put the red X on your exact location, and cut and paste the URL here.

Okay, let's go ahead and do this. Here's my location:

http://www.topozone.com/map.asp?lat=...ad83&layer=DRG

Quote:
I have no need to steal a CM parabolic or a 40' tower, and wouldn't take something that didn't belong to me anyway.

Oh, sorry for the vague wording. What I meant was, I've read posts in the past from folks who say they'd really like to find a CM parabolic. I was concerned about the extremely slim chance that someone might be nearby and try to BUY one the ones in my area. I guess I'm overestimating the demand for these things, huh?
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post #12 of 27
1/4/08 at 8:31pm
Quote:
Originally Posted by Jungle Jim View Post

Okay, let's go ahead and do this. Here's my location:

Well, now I see why there are so many old CM dishes in your neighborhood!

From www.tvfool.com, here's the channel 13 data for your location:

WKYT-DT 9.5 KW -125.0 dbm 51 degrees true
WBKO-TV 316 KW -95.4 dbm 251 degrees true

So, it's nearly impossible to receive anything at -125 dbm even without interference. Next, the station that you want, WKYT-DT, is 29.6 db weaker than WBKO.

Therefore, you need an antenna with as much gain as possible and a null toward WBKO of about 40 db! Stagger stacking by itself won't be enough. You would need four 10 element channel 13 yagi's stacked in a box with the top two stagger stacked with the bottom two stacked horizontally with the horizontal stacking distance set to give you a null 160 degrees from the main lobe. I have actually done this myself and, ironically, it was also on channel 13. Here's the location:
http://www.topozone.com/map.asp?lat=...ad83&layer=DRG
At that spot, Rochester is 166 degrees away from Albany. On my first trip to the sight I could see WNYT in Albany when aimed east and hear channel 13 in Rochester, NY when aimed west. In that case the analog signal that tvfool calculated would have been -105 dbm ended up with a perfect analog picture with no noise at all.

First select the right antennas: Here's the best choice: 10Y13S
http://www.wade-antenna.com/Wade/cutchannel.pdf
Or try this Antennacraft: http://www.warrenelectronics.com/antennas/y10713.htm
Winegard also makes a 7-13 10 element yagi, but it's performance on channel 13 is deficient.

Next, learn the basics of how to stack them. The stagger stack offset distance for channel 13 is 13 7/8". The horizontal stacking distance for a null at 160 degrees is 81". The vertical stacking distance is not particularly critical, but 5' masts would be about right. A quarter wavelength of RG-6 on channel 13 is 10.8".

Is this something that you would like to try yourself? If so, I can provide additional details.
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post #13 of 27
1/4/08 at 8:53pm
Thread Starter 
Tower Guy, I can't begin to tell you how much I appreciate your help! I've read just enough on this board in the past few months to be dangerous, so some of what you have told me has gone over my head. I don't plan to do anything until it warms up in a few weeks, so that will give me time to either study up some and/or show your posts to an installer who will know what to do.

Once again, thanks much! I'll let you know if I decide to give it a try.
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post #14 of 27
1/4/08 at 9:05pm
Quote:
Originally Posted by Jungle Jim View Post

Some of what you have told me has gone over my head.

More good reading about special stacking:
http://www.anarc.org/wtfda/stagger.pdf
http://www.kyes.com/antenna/stackluge.html
http://www.simplicitytool.com/stagge...k_VHF_quad.pdf
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post #15 of 27
1/4/08 at 9:49pm
I don't know that a stacked 4228 is going to do you any favors. My single 4228 never struck me as peculiarly directional, unless the signal was weak, very distant and not interfered with.

The 91XG seems to be the antenna of choice for people worried about ganging and directionality.

And then you're also confronted with 13 being upper VHF. Don't neglect the fact that channel 13 is quite a ways lower frequency than UHF's bottom of ch 14 and 15. There's a respectable gap in frequencies.

I've had better VHF success with an old Radio Shack VHF + the 4228 into a CM 7777 pre-amp I have than I had with trying the CM 4228 by itself.
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post #16 of 27
1/5/08 at 12:44pm
[quote]I doubt that antenna manufacturers will make anything better for UHF than the XG-91/4228.[quote]

The XG-91 is from Antennas Direct. They will shortly be introducing several new antennas. Antenna design and efficiency has changed drastically in the last few years, do to computer designing software. Check them out.
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post #17 of 27
1/5/08 at 2:12pm
[quote=antennaguys;12697037][quote]I doubt that antenna manufacturers will make anything better for UHF than the XG-91/4228.
Quote:

The XG-91 is from Antennas Direct. They will shortly be introducing several new antennas. Antenna design and efficiency has changed drastically in the last few years, do to computer designing software. Check them out.

Hmm, maybe a hybrid design based on the 91xg that will also do high VHF?
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post #18 of 27
3/3/09 at 7:52pm
Quote:
Originally Posted by Jungle Jim View Post


CM 4251 parabolic?

Here's one for sale:

CM 4251 UHF Para-Scope

>Parabolic UHF antenna

I'm still searching for info, but I'm thinking about erecting an old BUD (Big Umbrella Dish) and use it as UHF antenna. I can get signal at ground level with cheap UHF antenna. Just have not come across specific details on what to replace feedhorn with yet.
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post #19 of 27
3/4/09 at 8:56am
Quote:
Originally Posted by Marlboro_23 View Post

I'm still searching for info, but I'm thinking about erecting an old BUD (Big Umbrella Dish) and use it as UHF antenna. I can get signal at ground level with cheap UHF antenna. Just have not come across specific details on what to replace feedhorn with yet.

That's easy enough: a UHF antenna. The Parascope appears to use a 2-bay reflectorized bowtie. The Winegard version used a single reflectorized bowtie, IIRC.
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post #20 of 27
3/4/09 at 9:58am
Quote:
Originally Posted by nybbler View Post

That's easy enough: a UHF antenna.

On a 10' Big Umbrella Dish, I could use something like this?



At what distance from dish's center?
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post #21 of 27
3/5/09 at 12:27am
Quote:
Originally Posted by jspENC View Post

Antennacraft Y-10 will do the job for channel 13
Pay Television providers in general are beyond out of control.

yesssss! your signature is 101% correct! they are all wayyyyy out of control! i cancelled my cable tv sevice many months ago and none of those rat bastard korporate klown kriminal monopolists will ever get another penny from me!

its high time we all put up OTA tv antennas and/or fta satellite dishes to show them we dont need them!
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post #22 of 27
3/5/09 at 12:34am
Quote:
Originally Posted by Marlboro_23 View Post

On a 10' Big Umbrella Dish, I could use something like this?



At what distance from dish's center?

that would probably be a good start....and u would place it in about the same location as the original feedhorn....the focal point of the dish does not change at different frequencies.....and at uhf its exact distance is probably less critical than it is at c-bands 4 ghz frequency...

let us know how it works if u try it....
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post #23 of 27
3/5/09 at 2:10am
Quote:
Originally Posted by jspENC View Post

Antennacraft Y-10 will do the job for channel 13

Also check out the Winegard YA-1713, which are often a few dollars less at some sites and overall tend to hold up better in winter environments.

I have a pair of YA1713s stacked and they work very well. Stack them at 40 inches for the entire band. (7-13)
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post #24 of 27
3/5/09 at 8:56am
If you have cash to burn, look on fleabay. There is a CM4251 for $500. That's 1/2 the price of the other link posted, but still, rather steep of a price. You could make one sweet stack of Channel Cut yagi's, or VHF-Hi Yagi's for that price.

~ryan
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post #25 of 27
3/5/09 at 9:08am
Quote:
Originally Posted by pm3839 View Post

let us know how it works if u try it....

I'll have to locate a 4" pole first...cheap to do, if I can find a pole.
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post #26 of 27
3/9/09 at 3:31pm
Guys,

I've got a Channel Master 4251 seven foot parabolic TV antenna for sale. I bought 2 of these antenna in the 1990's. Installed one in my attic and left the other one in the box. My wife wants me to get it out of the basement, so I put it on eBay. Some companies are asking $1,000 plus $110 for shipping. I am asking $500 on eBay, and you can arrange your own shipping or pick it up at my home in Peoria, IL.
*
If interested, just go to eBay and do a search for Channel Master 4251.
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post #27 of 27
7/3/09 at 10:35pm
That thing better be made out of gold for that price.

Actually, I had a dozen of these in the backyard, and comparing them to the XG91, the XG91 actually did better with capturing the digital signals.

You are buying a big bulky beast that is inflated in price. I was selling mine for $60 bucks.

Quote:
Originally Posted by wwj1205 View Post

Guys,

I've got a Channel Master 4251 seven foot parabolic TV antenna for sale. I bought 2 of these antenna in the 1990's. Installed one in my attic and left the other one in the box. My wife wants me to get it out of the basement, so I put it on eBay. Some companies are asking $1,000 plus $110 for shipping. I am asking $500 on eBay, and you can arrange your own shipping or pick it up at my home in Peoria, IL.
*
If interested, just go to eBay and do a search for Channel Master 4251.
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