Originally Posted by tylerSC
Mr. Calaveras, looking at the photo in your avatar, you have one of the premiere antenna set ups available today. Looks like 2 91XGs for UHF and 2 Winegard 1713s for HiVHF. What type of splitters did you use to connect the duplicate antennas, and what type of preamp are you using? And did you use a UVSJ?
"Chuck" is good enough.
The VHF antennas are a pair of homemade log periodics. The 1713 doesn't have a very good F/B ratio and that was all important at my location. Details are here although the page needs a little updating:
What's not visible in the avatar is an FM antenna below the TV antennas that is part of the system.
I spent a lot of time optimizing the antennas for the best system noise figure I could get. I am not using a standard ferrite power combiner to combine the antenna pairs. Instead I use 1/4 wave matching sections of 50 ohm coax to transform 37.5 ohms (two antennas in parallel) to the 75 ohm preamps. The matching section and the coax from each antenna is soldered together inside a small metal box. I measured the loss and there is no loss beyond that in the coax itself unlike ferrite combiners which add 0.5 to 1 dB loss.
I also eliminated the 91XG transformers by using a 4:1 coax balun made out of 93 ohm coax. This picked up another 0.5 to 1 dB since the coax balun loss is only 0.1 dB or so.
On UHF I'm using a 30 dB gain 2.0 dB noise figure Tinlee preamp. Philip Lee at Tinlee told me the noise figure typically measures 1.5 dB. On VHF I'm using a Kitztech 0.4 dB noise figure preamp. I can get away with a preamp with no filtering here because I have no very strong VHF signals to overload it. I'm using a Tinelee 16 dB gain preamp on FM.
I'm using Tinlee diplexers which pass DC on all ports. The FM and high VHF antennas are combined through a diplexer that splits the bands at 156 MHz. One port passes <156 Mhz and the other 156 to 800 MHz. The output of that diplexer goes into the VHF input of a standard Tinlee VHF/UHF diplexer. The 91XGs go into the UHF input. The output of that goes down 575' of coax to my house, 430' of that is Trilogy M2 1/2" CATV hardline. It's the only way to get the loss low enough to get the system to work.
In the house there is one power inserter to power all three preamps. I have a second 156 MHz Tinlee diplexer to split off the FM signal to a tuner and high VHF/UHF to the TV. I also have a Tinlee channel 18 notch filter to knock KUVS down by 25 dB which is my one really strong local station that would otherwise overload the TV.
Experiments have shown that the Tinlee 30 dB UHF preamp is not overloaded by KUVS which has a noise margin measured at 69 dB!
ChuckEdited by Calaveras - 8/3/12 at 11:21am