I have not had an issue swapping out old cameras with TVI cameras and re-using my 5-year-old baluns.
We sell CVI compatible baluns as do GEM and others. Most short runs seem to work with ALMOST any balun. I've been told when you are pressing the distance to use HD baluns and in no case ahould you use amplified baluns, although I haven't tried it personally.
I spoke with NVT and they said HD analog would not work with existing NVT baluns because HD analog uses different frequencies.
Makes sense? Anyone try it with NVT?
They work with regular baluns, make sure its not the super cheap kind. I can get it to run barely at 1000ft with high quality regular video baluns. On cheaper baluns maybe 400ft or so
Old baluns can work up to a "certain" distance with a poor quality signal transmission. New HD baluns offer better signal transmission on longer distances. HD uses a different frequency spectrum. But if you want save money, buy a poor HD camera with a CCTV balun : "it works" too.
If it's any help... I recently replaced a couple analog domes with Axis cameras (PoE only), using Altronix eBridge EoC+PoE adapters. One camera refused to come up and the eBridge wouldn't show me a SLOC link with its partner adapter. I tested the coax and found a short in it (probably explains why that camera was being troublesome in the first place), so as a last resort, I threw a set of GEM baluns on the 18/2 power line... and it worked flawlessly.
Granted, this run was maybe 50 feet maximum. Still... it worked.
A year or so ago, I did the same thing inadvertently with regular non-PoE eBridges, running two cameras over a more substantial (probably 75-80') length of 22/4 station-Z. I was tracing another run that wasn't behaving, and discovered that the coax for two cameras coming from the DVR connected to baluns under a desk in another room, then over the station-Z, and back into coax before entering the cameras' environmental housings. We'd just swapped out the cameras and added the EoCs at both ends, and they came right up, so there was no reason to suspect anything strange with the runs.
I threw a set of GEM baluns on the 18/2 power line... and it worked flawlessly.
Cool. I'm wondering if the Baluns were even necessary from a impeadance point of view, though they're a easy way of connecting the conductors, for sure.