GPS RTK on Existing Tower

[Trm70c]

I have a question for you infrasture type folks. We currently have a 100 watt uhf repeater connected to a dipole antenna via 7/8" heliax rigid line. The repeater is an old micor with a recently updated telewave duplexer. The repeater will be replaced in the next twelve months due to narrowband issues. It currently is licensed for 451.85/456.85.
Here is the issue:
We are looking into RTK error correction and would like to use the current tower setup to broadcast the error correction signal. RTK radios broadcast in the 460 range and range from 20 - 40 watts, they do not receive at all. What would it take to incorporate this into our current antenna system? If I understand repeater opperation correctly (which is a big if) the duplexer will protect the reciever on the repeater, but how do we keep the 100 watts coming from the repeapter from damaging the RTK radio. The gps antenna would only be mounted about 30 feet or so up the tower and the RTK controller and radio would be mounted in the repeater cabinet.

I guess I should mention, the RTK is used for precision agriculture. We use gps for planting, harvesting, spraying and variable rate fertilizing.

Ideas, thoughts, and general comments are appreciated,
Thanks again,
Tyler

[Bill_G]

Normally I'd say you need a combiner. But, because you are also receiving on that line for the repeater, I'd have to think about it. Depending on the type of rptr duplexer you have, you may be able to use a set of cavities with tight skirts on the gps diff xmitter. You may be better off putting up an antenna for the diff.

[Trm70c]

Telewave TPRD-4544 400-470 MHz Pass-Reject Base Station Duplexer

But yes, even at a couple bucks a foot, plus labor, another antenna may be a cheaper option after all.

[RFguy]

Add a Sinclair C3034 or C3037 for your new 460 MHz tx. It installs in the feedline between your existing duplexer and the antenna. I would also sugest adding an isolator to each TX.