Maybe I was not clear or specific with the problem Gary we are seeing. By raw sweep I mean the return sweep when this problem is going on looks like forward raw sweep before normalization. Picture return sweep looking normal, then out of nowhere down at 5 dropping anywhere from 6-10 db and at 40 dropping around 4 db, which reminded me of raw sweep. In the mean time, modem transmit levels rise. Have looked to see it forward is affected, no, noise at amp, none. I had hard time picturing what was going on when told about it as have never heard or seen anything like it. Then while sweeping both ways 2nd time around, I saw it happen but it only lasted about 10-15 seconds and then went back to normal. Then another time it lasted longer. Tracked it back to amp 5 in cascade. Amp 4 was normal. Started trouble shooting and it disappeard. Next day came back. This time amp 4 showed it but amp 3 did not. Also seen it at amp 6 (last amp) but not at amp 5. With it showing up differant places makes it hard to track. The whole time this is going on of course the modem transmit level rises as does the upstream quam which is at 28. Maybe wrong but that to me is a normal reaction as the return path drops as described. Input I have gotten is anywhere from bad cable which has been tdr'd, nothing shows, to an electrical impulse getting in from bad ground. This node, gainmaker, has 4 outputs and this is the only leg that has this problem and it never makes it past amp 4, 1,2,&3 have never been affected. The reason I brought up about terminators was while sweeping a differant node I was doing a le and when switched to return saw had a blown terminator. Went to eol tap, hooked up the 6000, hit return and saw return sweep looked like I described with forward raw sweep instead of the normal jagged peaks a blown terminator shows.
replaced terminator and return went to normal. Hence that got me wondering about the issue above, could it be a intermitant blown terminator even though never seen an intermitant one. Its either blown or good. am not sold that this could be, just am thinking and looking for what could be causing the above intermitant issue and looking for input as to what others have saw and fixed. Thanks for reading and replying as this one is a puzzle looking to be solved.
Re: Return Path
Member #: 315
Registered: 1996-2001
Posted:
79
Name:
Mark Dahl
Name:
Mark Dahl
Company:
Communications Construction Group
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