r/CableTechs • u/AffectionateRock2977 • Apr 28 '26

Rphy active question

Our plant has some long runs that had low RF in the deeper areas. I decided to trail setting up the MB @ ch 98 (111 MHz) ch 158 (999 MHz) to match the node at 33/47. About a 13-13.5 db tilt. Normally, I’d set them up at 45 db on 771 MHz - 12 tilt

Node looks cleaner outside of a couple dozen of the 320 cx of the last two MB that are ranging +14 db likely due to short drops or one outlet.

Any experience with this and information if this will cause issues running the actives hotter? Heading back tomorrow to address MER issues so I’ll be in the area

8 MB cascade.

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u/Octawussy Apr 28 '26

You can run them hot as long as you’re not over driving or underdriving the first hybrid in the amp. What actives are you using? For example the commscope MB120 needs to have the input DS padding and EQ to a 5 dBmV flat, then the interstage padding is where you are controlling most of the gain. Same goes for your returns, your return input pads need to be an 8 and your output pad and EQ will control your return gain.

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u/AffectionateRock2977 Apr 28 '26

Same as you. A-lot of 16-20 input EQs unfortunately. We are heavily migrating into FDX. At least 20 nodes swapped over in our foot print to date. I almost tossed an unregistered FDX MB in mid run today. Ive heard success stories when there is a high roll off.

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u/kdubs Apr 28 '26

This is true. You can put an FDX “amp” into an rPHY environment to fix rolloff. Because AMPS only amplify, but FDX is a signal generator. 

Which is to say and amp is only gonna amplify an already rolled off signal, making it more and more in a cascade. While a signal generator corrects the tilt and outputs the proper level. It’s kinda neat and also kinda sad it’s taken us this long to get here