Originally Posted by ChiwaukeeOTA
Thanks for joining the thread.
So, making the antenna longer with more elements? No Problem! I still have the rear sections with reflectors, and directors. I could salvage parts from them. I'm curious on how to space the directors and width. Any advice there?
I had no choice than to guess on spacing. ..
Combining. I started with the Holland GHS 2PRO combiner but ended up using a Winegard CC-7870 for no particular reason. I think they both are parasites. Would like to know about phasing harnesses though..
I have not applied the Kitz Tech Amp - yet. I had consider buying more than one and pre-amping before the combiner, but I've heard different things about that. What's your view?
To do it right, the antenna needs to be modeled. Absent that, I have seen some long antennas where the director spacing and length remains the same after the first few directors. If you were to do that, all additional directors would be 21 3/4" long and the spacing would be 10 1/2". The final director would be the 20 3/4" original one with the same spacing. This is a guess is on my part. I'm pretty sure that making the additional directors longer again is not the right thing to do.
All those splitters used as combiners have at least 1/2 dB loss. There is a way to make a nearly lossless combiner. Use a 1/4 matching section. I've done this several times and it does work. The matching section is a 1/4 wave piece if coax whose impedance is the geometric mean of the two things you're trying to match. Two 75 ohm antennas in parallel is 37.5 ohms. The preamp (or feed line) is 75 ohms. The correct impedance for the matching section is very close to 50 ohms. If you use a piece of RG-58 or R-8 with solid polyethylene dielectric, the length is exactly 10". Attached is picture of a UHF version I made. The little box can be a 2 way splitter with the guts removed and replaced with wires. The matching section is very broadband and covers the entire high VHF band with very low loss. The length of the matching section includes connectors.
I had a pair of 12 element log periodics up for some years. Eventually though I ended up with a single 22 element log periodic on an 18' boom. Even though it is long, it's easier to deal with than phasing a pair of smaller antennas. It's the best high VHF antenna I ever used.
I also tried the idea of using two preamps on phased high VHF antennas. Sometimes it worked but sometimes there would be feedback between the two antennas and the oscillation would wipe out all the stations. Don't bother with it. Stick with one preamp.
The 22 element LPDA plus the KT-200 preamp is a very good combination and it's simpler than phasing antennas. See attached image.
In my experience, once you have a good antenna like the 30-2476 up in the air, it is very hard to get much improvement. Twice the antenna can approach 3 dB and 4 times the antenna can approach 6 dB. 10 dB improvement is a fantasy.