There's probably a few things that could be going on, but here's a couple of things I would want to know or try that I cant tell if you've tried yet.
(1) Where are you seeing this 2db jump? Is this a spurious spike, or just a slow drift? Are you testing directly out of the modulator(and are you padding it)? Have you seen this exact same level jump from mod to node? Are there any 860 components in your test setup and/or plant that would pose a problem? How about 870? Freq ratings usually work out of the box...but I've seen over time some active RF components can tend to lose some of their upper boundaries(like driver amps, etc).
(2) As cabledog suggested...have you tried putting a reliable video source over the mod? Have you also tried monitoring the mod for these spikes at EIA 133? How about 115? I'd rule out the mod's ability to put out a consistent carrier first...then see where it's breaking point seems to be.
You may have thought of these already...but that's the first place I would look. A little more info, and we might be able to make some better suggestions.
Re: ? Regarding the use of an analog carrier @ 859
Member #: 46734
Registered: 6/11/2006
Posted:
54
Name:
Steve
Occupation:
Engineering Manager
Location:
USA
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