Chris wrote: >1) I read the Thunderbolt user manual and did not find any meaningful >spec on the antenna except that it is amplified and uses DC power in >the coax. What signal level is the Thunderbolt expecting? oes it >want a 24dB antenna or more or much less? The antenna Trimble specifies has 35 dB of gain. Tbolts work with 26 dB antennas, but like 35 better. >2) I want to feed two GPS units with one roof mounted antenna. I >figure that splitters are just a transformers and will not pass DC to >power the antenna. There must be an easy way around this. HP and Symmetricom supply 2- and 4-way splitters specifically for GPS applications (see, for example, the Symmetricom 58535A at http://www.symmetricom.com/media/files/support/productmanual/097-58535-01-iss-1.pdf). They typically have low-gain amplifiers and pass DC to the antenna. Readily available on eBay and (at least in the past) from a listmember at attractive prices. Best regards, Charles