Originally Posted by gone hiking
Not sure if there's a difference with what I have and the one in the link. Model #s
are almost the same. Mind has an "S" at the end and the other has a "Z". In trying different configurations I discovered water inside the grommet on the Clearstream connector. When I disconnected the DB2e to islolate the Clearstream to see if it would improve VHF from Mt Sutro, it was a complete failure. So I reconnected everything through the combiner like before and now virtually no VHF at all. UHF is a little worse with just the DB2e though. I think water did something to the electronics inside the Clearstream box where the coax connects and my fiddling with it set it over the edge somehow. If I replace it with a VHF only antenna, I may have to also get something better for UHF.
That looks like the correct part to combine the antennae, model number differences aside. However, if you simply open-circuited the UHF port when you disconnected the DB2e that is electrically incorrect; the unused port should have been terminated with 75 ohms. If you want to look only at the Clearstream VHF and don't have a 75 ohm termination handy, you can can join the antenna cable to the TV cable with an F connector female adapter, removing both the diplexer and the UHF antenna from the circuit. Water is not a good thing.
I see a couple options here:
1) Replace the diplexer on the assumption it was water damaged and that is the source of your problems. This presumes your setup worked well over the full range of weather and seasons, not just for a couple weeks or months. Not clear if this was ever a truly good setup, have to judge by your experience with it.
2) Change out both antennae for high-gain narrow beam models to improve signal level and reject off-axis multipath. Chances are you'll just be able to point at Mt. Sutro and pick up Mt. Allison anyway (works for me). RF35 will probably still be flaky, but you should get RF7 from Sutro anyway. I have had great results with the XG91 on UHF, haven't yet tried the Stellar VHF but the specs are good.
My impression is the narrow beam is at least as important as higher gain.