AVS Forum banner
Status
Not open for further replies.
1 - 20 of 20 Posts

·
Registered
Joined
·
3,223 Posts
Discussion Starter · #1 ·
Anyone try to get the benfits of the 8-bay with the extra gain of Paralleling(2) CM 4228 Antennas Together?


What are the techniquies required and the benifits derived?


Murray Kerdman
 

·
Registered
Joined
·
5,329 Posts
Quote:
Originally posted by mkerdman:
Anyone try to get the benfits of the 8-bay with the extra gain of Paralleling(2) CM 4228 Antennas Together? What are the techniquies required and the benifits derived?
Murray, Doing this is no simple task. CM does not make Stacking Bars for this antenna. In fact, I don't believe that they make them for any of their models anymore. The bars are for summing two antennas together and providing proper source and terminating impedance's.


If you want to give it a go, then connect the two antennas together using (two) equal lengths of 300 ohm ribbon cable. The ribbon cables, from the antennas, should terminate into a Combiner/Separator (300 ohm in/75 ohm out)[keep the ribbon cable as short as feasible]. Twist the ribbon cable several turns before connecting.


------------------

Wendell

Technical Services Supervisor

MAETV


[This message has been edited by Wendell R. Breland (edited 04-29-2001).]
 

·
Registered
Joined
·
1,273 Posts

·
Registered
Joined
·
35 Posts
Hey Barry, I tried to check out that stacking link, but it failed. Is the link right, or was the server just down?


------------------

STOP DVI/HDCP!!!!!
 

·
Registered
Joined
·
830 Posts
Quote:
Originally posted by Eki:
Hey Barry, I tried to check out that stacking link, but it failed. Is the link right, or was the server just down?

The link worked fine for me at 10:15AM EST


 

·
Registered
Joined
·
3,223 Posts
Discussion Starter · #6 ·
Yes, I too got the link justn fine.


Thanks it iis very informative.
 

·
Registered
Joined
·
35 Posts
Excellent link. THe server must have been down before. Thanks for the great info!


------------------

STOP DVI/HDCP!!!!!
 

·
Registered
Joined
·
4,129 Posts
Wow! Awesome article. It's dated 1975! I wonder if there has been much advancement since then given the decline of OTA through "the cable years"?

Thanks for the link. Just kinda makes ya wanna run out and grab four 4248s and have at it... and not because I need to!! What a geek.




------------------

The button is labeled "Play", not "Pay". STOP the MPAA!

Our Silent Angels
 

·
Registered
Joined
·
1,273 Posts
'glad you guys found the link useful. It was orginally posted on this forum some months ago by another member. I remembered reading it at the time, thought it was pretty good, did a search and managed to find it.


------------------

You have a right to install OTA and dish antennas on property under your control.


See http://www.fcc.gov/csb/facts/otard.html
 

·
Registered
Joined
·
4,129 Posts
It indicates to use the wavelength of the lowest frequency that will be used. I don't know where a good chart of wavelengths exists, but I'll bet that someone posts a link here by the end of the day http://www.avsforum.com/ubb/smile.gif



------------------

The button is labeled "Play", not "Pay". STOP the MPAA!

Our Silent Angels
 

·
Registered
Joined
·
5,329 Posts
Quote:
Originally posted by Glenn_L:
It says to space antennas one way length apart, how can you find out the size of the wave length? Won't it be different for each station?
Glenn, The wavelength in meters is: Wavelength=300,000,000/Frequecy, and the wavelength in feet is: Wavelength=984,000,000/Frequecy. (The equations for In Air only) Note: See PS


The spacing will only be optimal at the frequency (TV Channel) chosen. If you plan to stack antennas, then take the average of your desired channels and use that to calculate the spacing. Example; CH 17, CH 21, CH 27, and CH 38 is available. Then I would use [(38-17)=21] [21/2=10.5] [therefore 17+10.5=27.5] CH 28 to figure the spacing.


Or, If CH 38 was the most problematic, then I may use it to figure the spacing.


P.S. Frequency is in Hertz, Wavelength is in meters or feet. Thanks SwampFox. [The original post was referenced to kilohertz.]

------------------

Wendell

Technical Services Supervisor

MAETV


[This message has been edited by Wendell R. Breland (edited 05-01-2001).]
 

·
Registered
Joined
·
3,681 Posts
How's this.


FM-TV Audio Broadcast, UHF Wide Band :

(Channels 14-69 in 6 MHz steps):


475.750: Channel 14

805.750: Channel 69


There is also a small error above. 300,000 / sec is the speed of light in kilometers not meters. So to get the answer in feet you need to use 983,569,089 as the factor.


Example wavelength of 600 Mhz is

983,569,089 / 600,000,000 = 1.69 ft

or ~ 20 1/4"



SM



[This message has been edited by Swampfox (edited 05-01-2001).]


[This message has been edited by Swampfox (edited 05-01-2001).]
 

·
Registered
Joined
·
5,329 Posts
Quote:
Originally posted by Man E:
It indicates to use the wavelength of the lowest frequency that will be used. I don't know where a good chart of wavelengths exists, but I'll bet that someone posts a link here by the end of the day http://www.avsforum.com/ubb/smile.gif
M E, Close anyway!! A good listing is from the Channel Master Catalog . After the site loads, click the radio button, then select catalog. It is a 2.2meg file in .PDF format. The chart is on page 57.


------------------

Wendell

Technical Services Supervisor

MAETV
 

·
Registered
Joined
·
730 Posts
From the antenna stacking article:

-------------

From The June 1975 Issue Of ELECTRONIC TECHNICIAN/DEALER’

Stacking TV Antennas

By James E. Kluge

The author is a technical editor in the Engineering & Research Division of the Winegard Company.

-------------


An "antenna-stacking" article written by a guy named Kluge! That is just too funny!


I wonder if he is the origin of the term?

(some quick research)

Nope, perhaps a relative of his . . .
http://foldoc.doc.ic.ac.uk/foldoc/fo...gi?query=kluge



[This message has been edited by dagman (edited 05-01-2001).]
 

·
Registered
Joined
·
4,129 Posts
I am assuming that when we are talking about spacing that we mean center-to-center and not tip-to-tip. Right? No, I'm not up on the roof right now http://www.avsforum.com/ubb/wink.gif



------------------

The button is labeled "Play", not "Pay". STOP the MPAA!

Our Silent Angels
 

·
Registered
Joined
·
1,525 Posts
Quote:
Originally posted by Swampfox:
How's this.


FM-TV Audio Broadcast, UHF Wide Band :

(Channels 14-69 in 6 MHz steps):


475.750: Channel 14

805.750: Channel 69


There is also a small error above. 300,000 / sec is the speed of light in kilometers not meters. So to get the answer in feet you need to use 983,569,089 as the factor.


Example wavelength of 600 Mhz is

983,569,089 / 600,000,000 = 1.69 ft

or ~ 20 1/4"



SM


So the answer to the topic of this thread would be NO.


Since ch14 = 983,569,089 / 475,000,000 = 2 ft

and ch69 = 983,569,089 / 805,000,000 = 1.2 ft


The 4228 is 39.5" wide and it can not be done.


You could however stack two 4221's since they are only 20" wide....

But wait! CM beat us http://www.avsforum.com/ubb/smile.gif and made the 4228 which is two 4221's stacked.


Ideal freq for 4228 = 983,569,089 / 1.67 ft (20") = 588,963,526 or 588.963MHz... don't know what channel number that is?


OK, here is channel number:

CH # = ((589-475)/6)+14 = CH 33


Glenn



[This message has been edited by Glenn_L (edited 05-01-2001).]
 

·
Registered
Joined
·
3,681 Posts
Would it be possible to stack them in a vertical manner on the same mast. Then you would just make sure that the bowties are 8", as they are on each unit.

I guess it is a lot easier to stack Yagi.


SM
 

·
Registered
Joined
·
58 Posts
Quote:
Originally posted by Glenn_L:



You could however stack two 4221's since they are only 20" wide....

But wait! CM beat us http://www.avsforum.com/ubb/smile.gif and made the 4228 which is two 4221's stacked.

I did just this very thing over the weekend. Because of where I live, I am forced to have the antenna in the attic. The opening into the attic is only about 24in wide. I had single 4221 installed for a couple of months now, and while I could pick us some if the stronger stations, several others were too low. I am about 55 miles from the transmitters. With the attic opening not being big enough to put up a 4228, I decided to buy another 4221 and mount them like a 4228.


The mounting was pretty easy using a 4ft piece of punched angle iron from Home Depot. I cut the piece in half and attached the two antennas, side by side, to the angle iron. The fit was perfect. The whole assembly was attached to a waterpipe using the center holes of the angle irons. I used two short pieces of twin-lead to the matching transformer. Make sure that the two antennas are in phase.


I am quite please with the results as now all the available channels are strong enough to be able to watch.


BTW, I ordered first one from Starks. The second 4221 I got from Uncle Joe's True Value (they have it listed as 3021). Ordered on a Wednesday and it was delivered on Friday and was $8 less than the first one.
http://www.unclejoes.com/tv_antennas.htm (no affiliation)


Tom
 

·
Registered
Joined
·
1,525 Posts
It says to space antennas one way length apart, how can you find out the size of the wave length? Won't it be different for each station?


Glenn
 
1 - 20 of 20 Posts
Status
Not open for further replies.
Top