View Single Post
Old 14-Jun-2013, 6:13 PM   #29
Junior Member
Join Date: Jun 2013
Posts: 5
I made a quick 300 ohm lead in, I did use the 75 ohm adapter that was on the antenna as well. Just using 300 ohm into a Diplexer (VHF/UHF) did not work very well.
Overall it gained about 4Db into the RFM151, I compared the stock HDB8X (including it's combiner) to my modified 300 ohm HDB8X (pictures after I post this, because of the delay). I was a little surprised I didn't have a bigger difference, but 4Db when you are in fringe is huge. I also did not use a preamp.
I am figuring there is a better way than the quick way I did the 300 ohm conversion. I have not compared it to the 4228 yet either, but I suspect they will be close to the same. The flexibility of the variable azimuth would give the HDB8X and advantage for those that are closer to the transmitters.
With the stock HDB8X pulling the left side back about 4 degrees, did increase the signal level by 1.5Db, this did not work with my 300 ohm version.
The test was also don at ground level, same mast and coax, just adjusting the antenna for peak readings.
One other note, I tried different lengths of 300 ohm lead in (from the joining to the adapter) and it appears picking a wave length of a channel for the lead in length, will help that channel
329049 is offline   Reply With Quote