Channel Master CM4228 Performance VHF

Rick0725 · 02-07-2006, 07:40 PM

Many forums praise the performance of the Channel Master cm4228 UHF antenna on high band vhf ch 7-13.

Hdtvprimer reported the gain per channel on the cm4228. Ch 7 and Ch 8 performance looks pretty troubling for ch 7 and 8... and positive for ch 9-13.

***ch7 -1db gain
***ch 8 -2 db
ch 9 3db
ch 10 6 db
ch 11 5 db
ch 12 4 db
ch 13 5 db

http://www.hdtvprimer.com/ANTENNAS/cm4228.html

I have experience with ch 12 in binghamton, new york and ch 9 in syracuse, new york. The signal comes in fine (but not as good as a directional VHF/UHF antenna).

Rochester, new york has ch 8,10,13... all transmitting from the same tower with the same power. I have a buddy there that aims the antenna to syracuse (east ) and gets the Rochester locals just fine received from the REAR!...and he said ch 8 comes in better than 10 or 13.

I have no experience with CH7.

Are the gain measurements just hypothetical?

What are your real experiences (not hypothetical) with high band VHF with the CM4228.

We are all curious. Lets set the record straight.

Rick

maicaw · 02-07-2006, 08:29 PM

Quote:

Originally Posted by Rick0725

Many forums praise the performance of the Channel Master cm4228 UHF antenna on high band vhf ch 7-13.
Hdtvprimer reported the gain per channel on the cm4228. Ch 7 and Ch 8 performance looks pretty troubling for ch 7 and 8... and positive for ch 9-13.
***ch7 -1db gain
***ch 8 -2 db Are the gain measurements just hypothetical?

that means that compared to a 1/2 wave dipole (the oval "driven" element that you connect the balun to on a normal VHF antenna) - if that were all you used ( similar to a Terk or clip-on dish antenna) the signal power would be about 10-40% less than a dipole -on those channels for a CM4228 - on the rest of the VHF the CM4228 would be 25-100% better than a dipole- and for UHF 1000% or more - the figures are logarithmic -3 db = 1/2 +3db = 2x, 6db=4x, 10db=10x, 20db=100x etc

jim5506 · 02-08-2006, 07:38 AM

All the values are calculated, there is no standard for real world trials.

maicaw · 02-08-2006, 03:18 PM

Quote:

Originally Posted by Rick0725

Are the gain measurements just hypothetical?

Quote:

All the values are calculated, there is no standard for real world trials.

http://www.marcspages.co.uk/tech/antgain.htm

Quote:

Antenna GainExplained
This one stumps even some of the most advanced RF engineers, that is, the "gain" of an antenna. Even the law states that the "Effective Radiated Power (ERP) will not exceed..." and this is based on the input into the antenna multiplied by the antenna gain. There is this concept that, the moment they exhibit gain, antennas magically create power within themselves. Sadly, this is not the case. If one examines an antenna it will be noted it is constructed of basic materials, the best being gold, silver, copper, then aluminium following on. These materials in themselves cannot create power.
Before we go into any explanations there are some terms that need definition so-as to assist in the explanation of antenna gain.
decibel (dB): unit of measure of loss or gain. Gain has a positive value, loss has a negative value, and is equal to10*log(Pout/Pin)
Antenna Gain: The relative increase in radiation at the maximum point expressed as a value in dB above a standard, in this case the basic antenna, a ½-wavelength dipole (as in Two-Poles) by which all other antennas are measured. The reference is known as 0dBD (zero decibel referenced to dipole). An antenna with the effective radiated power of twice the input power would therefore have a gain of 10*log(2/1) = 3dBD.
A note of warning: There is a second 'reference' used in antenna gain figures but is used to simply give an antenna a higher gain figure than what is truly achieved. It is known as dBi and represents a gain of an antenna versus an imaginary isotropic antenna - one that radiates equally in a spherical pattern (equal in all directions). It gives an antenna 2.14dB higher gain figure, but this is not a head start! This subject is covered in the paper "Cheating with Antenna Gain" http://www.marcspages.co.uk/tech/antcheat.htm ....In Closing:
Antennas do not somehow magically create power but simply focus the radiated RF into narrower patterns such that there appears to be more power coming from the antenna in the required direction.
As can be seen, "gain" is also "loss". The higher the gain of an antenna the smaller the effective angle of use. This is the part people forget i.e. that they have robbed power from other directions and superimposed it on the radiation in the intended direction.
This directly impacts the choice of the antenna for a specific function. Choosing the correct antenna is dealt with in "Choosing the correct antenna".

for the figures referenced in the quote below and much more info and links http://www.electronics-tutorials.com...nna-basics.htm

Quote:

People erect half wave dipoles in attics constructed of fine gauge wire - far from ideal BUT they get reasonable results by living with less than the "ideal". A lesson in life we should always remember in more ways than one.
The folded dipole antenna
The folded dipole antenna is probably only ever seen as a TV antenna. It exhibits an impedance of 300 ohms whereas a half wave dipole is 75 ohms and I'm certain someone will be alert enough to ask "why 75 ohms, if figure 3 above is 50 ohms?".
Within the limits of my artistic skills I have depicted a folded dipole antenna below.
Figure 4. - half wave folded dipole
One powerful advantage of a folded dipole antenna is that is has a wide bandwidth, in fact a one octave bandwidth. This is the reason it was often used as a TV antenna for multi channel use. Folded dipole antennas were mainly used in conjuction with Yagi antennas

.

Chocolab · 10-12-2007, 05:16 PM

I have played with the 4228 in dxing from about 125 miles. It really does see some vhf where my CM 4248 and Winegard 8800 don't see anything at all. During decent tropo conditions (not the freaky twice-a-year times where everything comes in perfectly), at night I can get a channel 8 and a channel 13 pretty well. There's also a channel 12 from another city about 90 miles away that comes in often.

For some reason, there's a channel 11 from the same 125-mile location that doesn't come in at all, ever. Not sure if their signal is weaker for some reason, or if a 25-mile-away local ABC digital on physical channel 11 is interfering.

tigerbangs · 10-13-2007, 08:04 AM

Having done a couple of 4228 only installations, I can tell you that the 4228 does a bit better than it's gain numbers might indicate on VHF. CT has a couple of VHF-DT stations: WTNH-DT from New Haven, and WTXX-DT from Hartford, and, here n New London, about 45 miles from both transmitters, the 4228 has no problems pulling a useful and solid signal on both stations.

Because of it's design, I am not at all sure that I would depend on a 4228 for ANALOG reception on VHF at that distance, but it seems to do fairly well for VHF DIGITAL reception: far better than any other UHF-only antenna I have used. The 4228's UHF performance is better than most other antennas, making it a decent one-antenna choice for digital reception. If you need low-band VHF ( channels 2-6) the 4228 is not an option.

If you need low-band VHF reception in addition to UHF, you are better off with an all-channel antenna like a Wade-Delhi VIP-305 or a VIP-306 and an Antennasdirect XG-91, but be sure that the antennas are separated on the mast by at LEAST 5', and that the XG-91 is tilted at least 10 degrees above the horizon.

texasbrit · 10-13-2007, 08:19 AM

I know it's only a sample of one, but I use the CM4228 at 41 miles from the DFW antenna farm at Cedar Hill. WFAA-DT is currently the only VHF digital channel, transmitted on channel 9, and I get excellent, stable reception. In 2009, WFAA is going back to its analog channel 8, and it will be interesting to see what happens given the theoretically lower performance of the CM4228 at channel 8. One of our other DFW stations is moving back to channel 11 also. But the CM4228 pulls in channels 8 and 11 with excellent analog signals so I am hopeful the channel 8 performance on digital will be OK. Of course the published CM4228 gain is only theoretical, so maybe in practice the channel 8 performance is better. Also I suspect that different samples of the CM4228 may have different VHF characteristics. I read somewhere that tying the two halves of the screen firmly together improved the VHF performance, anyone else seen that?

Rick0725 · 10-13-2007, 09:43 AM

Quote:

I read somewhere that tying the two halves of the screen firmly together improved the VHF performance, anyone else seen that?

it is a good idea to better attach the screens just for the sake of stability during wind gusts.

minimal and hardly noticeable is what I have experienced. the screens already touch in the first place not great but make contact none the less. The change is therefore not dramatic if that is what you are looking for.

I have installed several in the last 30 years. They do not perform to my satisfaction in my area. geography, hills, trees, and multipathic taming qualities were the main issues here. having ch 3 and 5 in syracuse did not help matters either

...whatever.

I tried tilting....no difference here...thinking that effect depends on the circumstances at the site...also noticed with instrumentation that different channels were affected differently which can become a headache . I left my 91xg horizontal.

specs ...a nebulous parameter for judging the actual performance of an antenna. there are just too many variables that come into play that affect reception.

Maybe I will dress up as a cm4228 this halloween and see what I can pickup.

sheezaym · 12-03-2008, 11:39 PM

As I have posted in other forums, the 4228a is a good performer for my VHF high band needs. My only digital VHF station is channel 7 which is located 65+ miles away. I get a 57% signal on it but it's solid, very few drop-outs. I am using a 0068DSB preamp also. After February 17, 2009 that stations goes to channel 29 and our local station which is 20.1 miles away utilizes channel 7 for it's digital signal. My 4228a even gets a clear picture on it's analog channel 2. The 4228a pulls in a decent picture on channel 9 analog. That's the station that is currently using 7 for digital. Nice to have everything on one nice looking antenna, not a cluster.

TonyTVTony · 12-04-2008, 04:17 PM

I get all my locals on a radio shack space ship antenna except for WLOS the ABC affiliate and would like to know if the 4228 would get me channel 13 @ 59 miles away? I hate to put up a VHF antenna just for this one channel. I live in 29625.
Tony

gcd0865 · 12-05-2008, 10:27 AM

If it's of any help to anyone, for comparison purposes, my YA-1713 pulls analog channels 11 and 13 (at 65 miles distance) around a 7 out of 10 in signal strength, just eyeballing it generally. My 4228 ends up around maybe a 4-5 out of 10 on the same channels. I'd estimate that the 4228 pulls about 60-70% of the signal strength on those channels as compared to the YA-1713. Since these antennas are in my attic, putting them outside (and higher) would of course yield better results. I agree with the previous comment that a single 4228 would probably be a good UHF/VHF-high solution for many people. I won't have any actual information to share on digital reception comparisons until next February, though.

sheezaym · 12-11-2008, 10:14 PM

Quote:

Originally Posted by TonyTVTony

I get all my locals on a radio shack space ship antenna except for WLOS the ABC affiliate and would like to know if the 4228 would get me channel 13 @ 59 miles away? I hate to put up a VHF antenna just for this one channel. I live in 29625.
Tony

I have no doubt it will work great!

02-07-2006, 07:40 PM	#1
Rick0725 Antennas by Committee Join Date: Jan 2006 Location: Clay, New York Posts: 1,558	Channel Master CM4228 Performance VHF Many forums praise the performance of the Channel Master cm4228 UHF antenna on high band vhf ch 7-13. Hdtvprimer reported the gain per channel on the cm4228. Ch 7 and Ch 8 performance looks pretty troubling for ch 7 and 8... and positive for ch 9-13. *ch7 -1db gain *ch 8 -2 db ch 9 3db ch 10 6 db ch 11 5 db ch 12 4 db ch 13 5 db http://www.hdtvprimer.com/ANTENNAS/cm4228.html I have experience with ch 12 in binghamton, new york and ch 9 in syracuse, new york. The signal comes in fine (but not as good as a directional VHF/UHF antenna). Rochester, new york has ch 8,10,13... all transmitting from the same tower with the same power. I have a buddy there that aims the antenna to syracuse (east ) and gets the Rochester locals just fine received from the REAR!...and he said ch 8 comes in better than 10 or 13. I have no experience with CH7. Are the gain measurements just hypothetical? What are your real experiences (not hypothetical) with high band VHF with the CM4228. We are all curious. Lets set the record straight. Rick

10-13-2007, 08:04 AM	#6
tigerbangs Antenna Maven Join Date: Feb 2005 Location: Springfield, MA Age: 54 Posts: 2,116	Having done a couple of 4228 only installations, I can tell you that the 4228 does a bit better than it's gain numbers might indicate on VHF. CT has a couple of VHF-DT stations: WTNH-DT from New Haven, and WTXX-DT from Hartford, and, here n New London, about 45 miles from both transmitters, the 4228 has no problems pulling a useful and solid signal on both stations. Because of it's design, I am not at all sure that I would depend on a 4228 for ANALOG reception on VHF at that distance, but it seems to do fairly well for VHF DIGITAL reception: far better than any other UHF-only antenna I have used. The 4228's UHF performance is better than most other antennas, making it a decent one-antenna choice for digital reception. If you need low-band VHF ( channels 2-6) the 4228 is not an option. If you need low-band VHF reception in addition to UHF, you are better off with an all-channel antenna like a Wade-Delhi VIP-305 or a VIP-306 and an Antennasdirect XG-91, but be sure that the antennas are separated on the mast by at LEAST 5', and that the XG-91 is tilted at least 10 degrees above the horizon. __________________ Real men don't use indoor antennas; neither do real women!

12-03-2008, 11:39 PM	#9
sheezaym How can anyone watch standard def? Join Date: Oct 2008 Posts: 17	4228A Does Fine For My VHF As I have posted in other forums, the 4228a is a good performer for my VHF high band needs. My only digital VHF station is channel 7 which is located 65+ miles away. I get a 57% signal on it but it's solid, very few drop-outs. I am using a 0068DSB preamp also. After February 17, 2009 that stations goes to channel 29 and our local station which is 20.1 miles away utilizes channel 7 for it's digital signal. My 4228a even gets a clear picture on it's analog channel 2. The 4228a pulls in a decent picture on channel 9 analog. That's the station that is currently using 7 for digital. Nice to have everything on one nice looking antenna, not a cluster.

12-04-2008, 04:17 PM	#10
TonyTVTony What is HD? Join Date: Mar 2008 Location: Southeast US Posts: 3	Channel 13 at 59 miles away I get all my locals on a radio shack space ship antenna except for WLOS the ABC affiliate and would like to know if the 4228 would get me channel 13 @ 59 miles away? I hate to put up a VHF antenna just for this one channel. I live in 29625. Tony

02-08-2006, 07:38 AM	#3
jim5506 Yellow Submarine Join Date: Dec 2004 Location: Lubbock, Texas Posts: 2,416	All the values are calculated, there is no standard for real world trials.

10-12-2007, 05:16 PM	#5
Chocolab What is HD? Join Date: Jun 2007 Location: North Texas Posts: 4	I have played with the 4228 in dxing from about 125 miles. It really does see some vhf where my CM 4248 and Winegard 8800 don't see anything at all. During decent tropo conditions (not the freaky twice-a-year times where everything comes in perfectly), at night I can get a channel 8 and a channel 13 pretty well. There's also a channel 12 from another city about 90 miles away that comes in often. For some reason, there's a channel 11 from the same 125-mile location that doesn't come in at all, ever. Not sure if their signal is weaker for some reason, or if a 25-mile-away local ABC digital on physical channel 11 is interfering.

10-13-2007, 08:19 AM	#7
texasbrit High Definition is the definition of life. Join Date: Sep 2006 Posts: 1,031	I know it's only a sample of one, but I use the CM4228 at 41 miles from the DFW antenna farm at Cedar Hill. WFAA-DT is currently the only VHF digital channel, transmitted on channel 9, and I get excellent, stable reception. In 2009, WFAA is going back to its analog channel 8, and it will be interesting to see what happens given the theoretically lower performance of the CM4228 at channel 8. One of our other DFW stations is moving back to channel 11 also. But the CM4228 pulls in channels 8 and 11 with excellent analog signals so I am hopeful the channel 8 performance on digital will be OK. Of course the published CM4228 gain is only theoretical, so maybe in practice the channel 8 performance is better. Also I suspect that different samples of the CM4228 may have different VHF characteristics. I read somewhere that tying the two halves of the screen firmly together improved the VHF performance, anyone else seen that?

12-05-2008, 10:27 AM	#11
gcd0865 High Definition is the definition of life. Join Date: Jan 2008 Posts: 31	If it's of any help to anyone, for comparison purposes, my YA-1713 pulls analog channels 11 and 13 (at 65 miles distance) around a 7 out of 10 in signal strength, just eyeballing it generally. My 4228 ends up around maybe a 4-5 out of 10 on the same channels. I'd estimate that the 4228 pulls about 60-70% of the signal strength on those channels as compared to the YA-1713. Since these antennas are in my attic, putting them outside (and higher) would of course yield better results. I agree with the previous comment that a single 4228 would probably be a good UHF/VHF-high solution for many people. I won't have any actual information to share on digital reception comparisons until next February, though.