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Old 11-Apr-2019, 1:58 AM   #1
dbseeker
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Hi VHF

Please pardon my amateur questions but this inquiring mind would like to know

1. Is the 5db of gain on hi-VHF of the C5 and the CM4228 equivalent?
Are their cartridges impedances equivalent for hi-VHF?
Is their gain across 7-13 relatively equivalent?

2. Is VHF wave absorption relatively blind to UHF reflectors? Of note, the C2 and C4 have the VHF dipole behind the upper part of the reflector. Combo antennas have the VHF elements behind the UHF array which I understand is a compromise. All things being equal, how much more efficient is the 2 antenna setup?

3. Please contrast the pro's and con's of balun vs cartridge signal efficiency for coax insertion.

4. If your weakest channel is hi-VHF, mounting it highest would seem acceptable to me ? ie the stacker as an example

Many thanks again for the expertise!!
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Old 11-Apr-2019, 10:52 PM   #2
Tower Guy
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There is no reason to try receiving a VHF channel using a CM 4228. The 4228 is a UHF only design. If your VHF stations are in the same direction as your UHF stations consider an ANT 751, HD 7694P, or Channel Master digital advantage. If you need or want a separate ZvHF antenna take a look at the Stellar labs 30-2476.
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Old 26-Apr-2019, 11:26 AM   #3
bobsgarage
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Cool 4228 HD is capable of some VHF

Sorry, since I don't own a 4228HD I really can't say that much about it. However, I've heard it can pick up some VHF. Apparently the old 4228 was better and actually picked up some VHF although they are supposed to be UHF only..

Although his website isn't often updated, Tom Ballister has done some great testing with data to back it up.

http://www.antennahacks.com/Comparis..._CM4228Old.htm

http://www.antennahacks.com/Comparis...228_vs_DB8.htm

I think it almost every case the two antenna solution is the way to go for high levels up reception of UHF and VHF.

I think Tower guy has a good suggestion. With the repack coming, it looks like the 4228HD is better on lower channels and teaming one of those up with a 30-2476 sounds like a good combination with the new repack. I have the 30-20 476 and it is a well made and highly capable VHF High antenna. Add to that there's not much variety anymore for VHF only antennas. Incidentally, it can actually pick up some UHF. Read Tom Ballister's comparison on his site.

As far as I know, this is the only place to get the 30-2476. They actually have a deal if you buy four of them, probably not practical for most.

https://www.newark.com/stellar-labs/...P_LastViewed_1

I can't answer your technical questions, maybe somebody will see, this answer your technical questions, which I would like to hear myself.


Last edited by bobsgarage; 26-Apr-2019 at 11:33 AM.
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Old 26-Apr-2019, 6:58 PM   #4
dbseeker
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Thanks for the replies!
The reason for the question was Channelmaster website documents boast a 5db gain on hi-VHF and I couldn't find any posts on any forum where CM implemented the changes Nist suggested to the harness since 2010.
My current setup is AD C4 with an antennacraft Y7-13 joined with the CM Amplify plus split to two TV's. It works well.
My questions were just various things that make me scratch my head.
The experts on these forums as with any experts in any field do and should keep advertising as honest as possible.
My cartridge question basically asks if that is a balun surrounded by plastic or is there somehow more efficiency to signal transfer?
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Old 27-Apr-2019, 2:15 PM   #5
Nascarken
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Quote:
Originally Posted by dbseeker View Post
Thanks for the replies!
The reason for the question was Channelmaster website documents boast a 5db gain on hi-VHF and I couldn't find any posts on any forum where CM implemented the changes Nist suggested to the harness since 2010.
My current setup is AD C4 with an antennacraft Y7-13 joined with the CM Amplify plus split to two TV's. It works well.
My questions were just various things that make me scratch my head.
The experts on these forums as with any experts in any field do and should keep advertising as honest as possible.
My cartridge question basically asks if that is a balun surrounded by plastic or is there somehow more efficiency to signal transfer?
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Last edited by Nascarken; 27-Apr-2019 at 2:22 PM.
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Old 27-Apr-2019, 3:32 PM   #6
rabbit73
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Quote:
Originally Posted by dbseeker View Post
1. Is the 5db of gain on hi-VHF of the C5 and the CM4228 equivalent?.....Is their gain across 7-13 relatively equivalent?
I assume you mean the 4228HD. Not really equivalent. The C5 gain curve is smooth; the 4228HD VHF-High gain curve has peaks and dips.





Quote:
Are their cartridges impedances equivalent for hi-VHF?
They should both have been designed for 75 ohm output. The printed circuit balun for the 4228HD was designed for UHF only; any VHF signals were incidental.


Quote:
2. Is VHF wave absorption relatively blind to UHF reflectors? Of note, the C2 and C4 have the VHF dipole behind the upper part of the reflector.
It bothers me that the dipole is behind the reflector; it should be in the clear. I don't know how much difference it makes.
Quote:
Combo antennas have the VHF elements behind the UHF array which I understand is a compromise.
Yes, it is a compromise as far as element locations is concerned but also how UHF and VHF are combined. Most combo antennas use shorting stubs to block UHF from the VHF section. The Winegard HD7694P and 7698P keep UHF and VHF separate in the CB8269 cartridge.
Quote:
All things being equal, how much more efficient is the 2 antenna setup?
The Winegard combos are more efficient than most other combos. My intuition says that separate VHF and UHF antennas are more efficient, but actual comparative measurements would be required at any particular location.

Quote:
3. Please contrast the pro's and con's of balun vs cartridge signal efficiency for coax insertion.
You haven't defined what type of balun and what type of cartridge, so I will have to make some assumptions.

There are several types of baluns.
1. Conventional ferrite core balun that is good for UHF and VHF.
2. Printed circuit balun now used for UHF antennas; not good for VHF.
3. Halfwave coaxial balun; low loss, but good for only one TV band: UHF, VHF-High, or VHF-Low.
Quote:
4. If your weakest channel is hi-VHF, mounting it highest would seem acceptable to me ? ie the stacker as an example
That assumption is only true if the signal strength is uniform at your location. In reality, there will be hot and cold spots for the antenna. The reviews for the Stacker are mixed Some users like it, others don't.
Attached Images
File Type: jpg AD C5 Gain.JPG (97.4 KB, 218 views)
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Old 27-Apr-2019, 4:43 PM   #7
Nascarken
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Quote:
Originally Posted by rabbit73 View Post
I assume you mean the 4228HD. Not really equivalent. The C5 gain curve is smooth; the 4228HD VHF-High gain curve has peaks and dips.





They should both have been designed for 75 ohm output. The printed circuit balun for the 4228HD was designed for UHF only; any VHF signals were incidental.


It bothers me that the dipole is behind the reflector; it should be in the clear. I don't know how much difference it makes.
Yes, it is a compromise as far as element locations is concerned but also how UHF and VHF are combined. Most combo antennas use shorting stubs to block UHF from the VHF section. The Winegard HD7694P and 7698P keep UHF and VHF separate in the CB8269 cartridge.
The Winegard combos are more efficient than most other combos. My intuition says that separate VHF and UHF antennas are more efficient, but actual comparative measurements would be required at any particular location.

You haven't defined what type of balun and what type of cartridge, so I will have to make some assumptions.

There are several types of baluns.
1. Conventional ferrite core balun that is good for UHF and VHF.
2. Printed circuit balun now used for UHF antennas; not good for VHF.
3. Halfwave coaxial balun; low loss, but good for only one TV band: UHF, VHF-High, or VHF-Low.
That assumption is only true if the signal strength is uniform at your location. In reality, there will be hot and cold spots for the antenna. The reviews for the Stacker are mixed Some users like it, others don't.
Yes that's true but Troposcatter Ground gain Radiation angle vhf.?
Thank you Rabbit ears for your input.Qsl Hf ??
And when I used the Winegrud 8200U when you get rid of the black box and hook up
A vhf/uhf amp to it what A big improvement 35:dbg vhv.wow/uhf45:dbg double wow.
And when stacking them Winegrud 's amp on tv on one person on the roof to adjust the ANTENNA apart and the other person at the tv sets when the picture come into play WOW that's awesome!!!!lol I like four shire things and the best results on my rf
Polarization and RECEIVE range WOW!!!on the vhf.&the other end uhf 91xg,Double. WOW!!

Last edited by Nascarken; 29-Apr-2019 at 7:33 PM.
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