I fully understand! These older modules if not correctly maintained previously may exhibit reflections and ground plane issues if the aluminum cover was ever removed and not properly tightened. The biggest problem would be that the cover screws were loose, missing or stripped out. In severe instances, I have seen the cover bent and forced back into place destroying the RF ground.
My advice if you were wanting to sweep the module from the RX output would be to REFERENCE directly from the RX OUTPUT via a "mini-SMB" cable or whatever connection it has. This reference would be FLAT with respects to both level and sweep response. Now, connected to an output RF testpoint, I would use my TILT COMP to reflect a negative tilt that (in theory) should be FLAT as the MDR board produces a tilt being an equalizer with adjustments. If the MDR produces 9dB of tilt from 55MHz to 750MHz, use a TILT COMP of -9dB. Adjust this depending on the specification of the unit. Now you can sweep to a FLAT line.
Assuming that there are NO reflections or grounding issues and everything is terminated properly, this should get you in the ballpark without using a bench setup. Remember,, looking at actual RF carriers to sweep from in the SCAN mode can be misleading. You do not want to peak your MDR board if you have low carriers into the forward laser inputs in the headend. Depending on the isolation of the RX testpoint, there could be reflections and false representations of carier levels. Unfortunately the only true test would be to directly open the circuit and read off the RX output.
Good luck!
Re: Jerrold/GI Starline BTN-M Node info
Member #: 7190
Registered: 1996-2001
Posted:
483
Name:
Greg Tobin
Name:
Greg Tobin
Company:
Interactive Broadband Technical Services
Occupation:
HFC Engineer/Consultant
Location:
www.interactive-broadband.com
Personal:
Experience:
~45 years
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