The D130 is a vertically polarized antenna and not designed for TV reception. The splitter is 75 ohm and the antenna and coax are 50 ohm. How are you connecting the LMR400 to the splitter? Splitter will have an insertion loss. So many issues. Did you weatherproof all outside connections?
Did you use a water proof sealant on the coax to antenna connection?
#1 Antenna Mastic
#2 Scotch 33 or 35 Tape
Keep in mind this works fine for my needs when it's dry. I went with the discone because I have low band vhf, vhf-hi, and uhf stations around me and also wanted a good general coverage receive antenna for scanners and other receivers. The impedence mismatch is a non-issue. I have an N to F adapter connected to a polyphaser arrestor, and then rg-6 with F making entry inside. Inside then connects to an FM trap filter which then feeds a +15db drop amplifier, which then feeds the 3 way splitter. Again this works brilliant when it's dry and I have no complaints at all until it rains. The connections at the bottom are admittedly not weatherproofed. However, they are shielded from weather mostly from the roof overhang. I've also checked them repeatedly for water and they remain dry. At the antenna, the coax connection is hidden from weather as it comes up inside the mounting pipe but IIRC I still wrapped it with e-tape.
It was working perfect with tv channels and all but now the signal drops when it rains?
Check the plastic insulator between the vertical elements and the bottom elements for any cracks that could leak in water.
/Ubbe
Right, works perfect then rain gets in somewhere. I haven't been on the roof yet to check the antenna for cracks. That's the purpose of this thread, to hear if anyone else has had that sort of issue with this specific antenna. I had a cheap Tram discone that fell apart but I thought I was getting a better quality one with this Diamond.
The loss from impedance mis-match is likely not significant. But the lost from the 3-way splitter, if not an active (having an amplifier) one, is significant. However, you did not say how high this antenna is relative to the average terrain and trees. Wet trees, particularly evergreens, can affect signal levels.
I agree on the impedence, it's close enough. Again, works fine when dry for my needs. I am feeding the splitter with a drop amp, so I am fine there. The trees however could be an issue. We have a line of pines up the side of the property between us and the city. I want to say the antenna is probably still 15ft or so below the tops of them. I did consider putting another 5 or 10ft of mast on it, but I can't load the chimney bracket too much more. It is the only antenna on it though.
Do you have a way to measure VSWR at several frequencies across VHF/UHF? If you can do a measurement when its dry and working fine then compare the VSWR after it rains and its not working it could tell you if water is getting into something and causing the problem.
That's worth a try, I can take an HT and a SWR meter outside and hook directly to the LMR. I didn't use an LNA at the top so I'd be able to use it for TX in a pinch.
