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Old 07-03-2009, 01:48 PM   #11 (permalink)
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I was thinking out loud. Sometime so loud I have to use ear plugs to hear myself.
I was a math and physics major but took a couple of EE course on basic electronics, which I used much more in work than my physics.

I am trying to pull out cob webs and remember what increases dynamic range in an amplifier. The one thing I remember is if you increase the delta of the rail voltages, the amp will have more dynamic range. I know it works with transistors and tubes. I used to build HF amps power supplies with as much voltage as I thought the tube could stand. This not only gave more power, but more dynamic range.

There are probably other designs and the devices themselves that have different ranges.

The one thing the Winegard HDP-269 doesn't have is an FM trap. I tend toward recommending the AP-8700. It has a lot of dynamic range and an FM trap.

The one thing you have to watch on HDP-269 (besides living next to an FM station) is enough gain in a large house with multiple TVs. 100ft of RG6 good and new is about 5db on the upper channels. A 4 way splitter that is well made approaches 7db at best.
That is cutting it close is someone has 50 ft to the splitter and 50 to a remote TV in the basement for example. I am sure you know, but for the benefit of others, once you use up all the gain in the amp, noise starts building up quickly.

I am thinking out loud again, so ear plugs required by OSHA... If you read this article that someone over at AVS turned me on to Testing for DTV Interference, by Charles W. Rhodes you can see, FM may be a bigger problem than apparent. So FM trap ahead of the amp is a good idea.

The 8700 is -21 or so dbm and the 269 is -14 dbm, which gives the 269 much more dynamic range, but again no FM trap.

I boils down to a well engineered home system, is the only way to go. However the concepts and math involved are beyond or unknown to 99% of the DYI OTA antenna installers.

I have to say the combo vs separate switch on the CM7777 is darn handy if you are experimenting.
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