New Channel Master CM-4228HD versus 'Old' CM-4228

A number of forums and web sites have published comments about degraded performance of the newest versions of this antenna. Predominantly the comments cite mechanical differences due to being manufactured in China versus domestically, and changes in the transmission harness and/or balun.

So the question becomes "Is there really any significant difference?"

To answer this, a newly purchased (June, 2009) CM-4228HD was compared to an older CM4228. As best known, the manufacture date of the older model is approximately 1990. Quick observations reveal there are indeed differences in materials and thus weight, as well as in the transmission network that couples the individual bays of this 8-bay design and balun, and thus possibly resulting in differences in performance.

The older CM4228 came to me with a common RG-6 F-Connector (75 Ohm) to twiin lead (300 Ohm) balun. In contrast, the newer CM-4228HD comes with an integral balun. Because the supplied 75 to 300 Ohm balun had no manufacturer or model number indications I viewed it as an unkown. I couldn't be sure it was the originally supplied balun or not, so I 1st compared the older CM-4228's performance using this balun and a TV-2900. [I have independently characterized a number of off the shelf baluns back-to-back, and found the TV-2900 to be one of the least lost baluns measured.] I found no significant difference using either balun; so I completed the comparison using the known TV-2900.

Channels 15 & 20:

Channels 17 thru 26:

Channels 30 and 33:

Channels 44 and 47:

Channels 47 thru 55:

And What About Hi-VHF?
As many have observed, the most recently purchased CM-4228HD's have demonstrated useful sensitivity for the Hi-VHF band. Is that different than the originally manufactured models?

Channels 7 thru 13:

Conclusion
The new CM-4228HD's UHF sensitivy is pretty close to the original. The signficant differences observed for the UHF channels captured are as follows:

UHF Channel	Observation
23	Older model exibits about 1-3 dB stronger signal.
30	Older model exhibits about 1-2 dB stronger signal.
15	New model exhibits about 1-2 dB stronger signal
44	New model exhibits about 1-2 dB stronger signal.

For every other channel observed the captures fall virtually on top of each other.

VHF Channel	Observation
7	New model exhibits about 1-2 dB stronger signal.
8	New model exhibits about 2-3 dB stronger signal.
13	New model exhibits about 4-6 dB stronger signal.

So, all things considered, this author remains pretty respectful of the new CM-4228HD's utility.

2010.12.30 Update:
Late last fall I implemented the recommendations of Ken Nist ("The HDTV Primer") regarding the transmission line "harness" for the new CM-4228HD. The evidence supports his assertion that the harness can be improved. The hack is described at this Nist Harness link.