Chris > >> Christopher Hoover wrote: >> >> >>>> Most (except for Trimble,..) GPS receivers and antennas >>>> are designed to use 50 ohm cable. >>>> Trimble Bullet GPS antennas have a 50 ohm output impedance. >>>> Trimble literature however is ambiguous in that in the >>>> Resolution T receiver datasheets talk about using RG59 >>>> to connect to the antenna. >>>> >>>> >>>> >>> FWIW, the Thunderbolt manual says this on page 3-5: >>> >>> -------- >>> Note - RG-59 is a 75 ohm coaxial cable. The ThunderBolt and >>> the Bullet antenna are compatible with either 50-ohm or >>> 75-ohm cable. Compared to most 50 ohm cable, 75 ohm cable >>> provides superior transmissibility for the 1.5 GHz GPS >>> signal and a better quality cable for the price. Mismatched >>> impedance is not a problem. >>> -------- >>> -------- >>> Note - The input impedance of the ThunderBolt RF input & >>> its antenna is 50 ohms. >>> -------- >>> >>> >>> I would also add that BNC and N connectors come in both 50Z and 75Z flavors. >>> In fact 75Z BNC connectors are pretty common, being used in professional >>> video applications. (Check surplus BNC patch cords carefully.) On the >>> other hand, 75Z N connectors are much less common, but were used in CATV >>> plants, IIRC. >>> >>> -ch >>> >>> >>> >>> _______________________________________________ >>> time-nuts mailing list >>> [email protected] >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> >>> >>> >>> For those of us who strive for the ultimate in performance with GPS timing receivers it is recommended that mismatched antenna cables not be used see:
http://www.bipm.fr/wg/CCTF/CGGTTS/Allowed/Recommendations/CGGTTS-Guidelines.pdf Bruce _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
