In Reply to message #374814 by SWeePTeK
Old School Member Buffalo Chips is not online, or is invisible.
12/2/2017 11:26:06 AM
Buffalo Chips Member #: 7190 Registered: 1996-2001
Posted: 435 View all posts by Buffalo Chips
Company: Interactive Broadband Technical Services Occupation: HFC Engineer/Consultant Location:
Re: Over equalizing - It's ok - NOPE!
Seriously?!?!  A person can disconnect the idiot light in a car but that does not fix the problem it indicates.

If that is their policy to over-equalize the return it is either because they can not or will not repair the problem of noise and related buildup at the lower end of the spectrum. Minor (wihin 1dB) is not considered overequalizing if it is trying to achieve a realistic spec baseline trace.

When it comes to a cable operator dictating a "system spec" (not the manufacturer as it is a guideline spec to follow) the designer of such a spec must be realistic in expected numbers to be achieved by the field technician especially with other factors like existing older bad passive devices, connectors and cable. That is unless all your amplifiers are connected with housing-to-housing connectors in a straight line with minimal signature contribution from other sources.

Another issue that many amplifiers have when "not in spec" is when some "bean counter" buys a poorly designed after-market return (or forward) equalizer that destroy the factory flattness specification. I have seen 1 amplifier go from a .5dB p/v to a 1.5dB p/v or higher by using another manufactured cheap equalizer. in 2 amplifiers this easily is 3dB p/v and so on.

Not all equalizers are designed equally. If you have a 3dB return equalizer designed for a Motorola amplifier 5-42/50-750 it will not give the same response as a 3dB return equalizer designed for a Motorola amplifier 5-42/50-860. There is a  version SEE-*** and the SRE-*** and both will fit in the slot and both can be the same value. This can cause a minimum of .5dB rolloff per amplifier due to the difference in the diplex filter designs. In a 6 amplifier cascade this is a 3dB rolloff. This example is with both Motorola equalizers being used. If a 3rd party aftermarket equalizer is used, it could be even worse. Every amplifier from any varity of manufacturers have this potential issue if the designed equalizer (not the value) is not used.

True there are 2 sides of the coin but in reality you can't make gold out of a pile of shit if that is what you are working with. Remember you equalize the signature response NOT the noise floor as seen on the spectrum analyzer.

This is what happens when corners are cut to get cheap parts and manufacturer recommened plug-in devices are not purchased. It is the outside plant technicians that have to fight to make it work. Just because the shoe fits does not mean it will be a confortable walk.

This member is a Regular Member.
0 Replies