Interesting, coverage of the 2 meter ham band. I've heard conflicting reports of the CZE, etc. equipment. Breakdown videos and blogs seem to show good construction on the inside, pro boards and decent low pass filtering of the output, but some say they interfere, or that there are clones that aren't as good as the originals. Some of this could be from uninformed people repeating bad info, or other sellers saying to beware to put a boost in their product line, so I'd bark to read heartily on the subject.
Another issue with most of those models is the pre-emphasis being set for 50 us instead of 75 as needed in the Americas, because these are all world market items. You can make up the 25 us in some software like Sonos Limit by setting pre-emphasis to 75 us, de-emphasis to 50. That's good, because you get the processing based on the 75 you're using.
Another thing to watch out for right now are the transmitters that use a chip that's all digital stereo generation, digital tuning and RF generation, KT0803L DSP stereo transmitter IC. That would seem to be the ultimate answer over most other cheaper transmitters that use an analog BH chip that's used in every FM relay product.
The new digital ones are spurious, increasing noise levels in the section of the band they broadcast in. That's been confirmed by evidence and spectrum analysis. They might be good for low power relay, but I wouldn't amplify them. It's tech that needs work.
Boom
