Today I have been looking at the options for bias tees that we can use for the UNITEC-1 receiver. A bias tee (aka. Bias -T) is a simple device that can inject DC voltage into a coax cable. It is often used to provide supply voltage to devices that are mounted on the antenna without the need for dedicated DC cables. In our case, the low noise converter (LNC) will be mounted on the antenna and the “cable length” between antenna and control room is 40 meters, so it matters a lot that we can use the already existing RF coax cable to also supply the DC voltage. Actually, the KU LNC 5659 C PRO that we will use can only be supplied via the coax.
We have two Bias-T on stock: The KU BT 271 N from Kuhne that was originally acquired for the S-band ground station and something called MSTTR001 from Snec – don’t have much info about this one besides that it should be good up some-GHz and 100 mA current.
As you can see, the KU BT 271 N has two N-connectors while the Snec has two SMA connectors but is mounted on this adapter thing so that the antenna end has an N-connector. The USRP + WBX or TVRX receiver has SMA connectors and the coax cable has N-connector, thus it seems that the Snec would be best suited. Unfortunately, the LNC requires 180 mA so we’ll stick to the KU BT 271 N, which can be used up to 1 A.