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I need to make some field antenna cables and connectors using RG-174/U
cable. If for for reasons of convenience and cost I use metal RCA
connectors, with there be a material difference in insertion loss?


there will probably be some impedance mismatch but in most cases the extra
loss will probably be minimal. worse than that are the mechanical and
weather proofing problems. they are much worse on rca than either bnc or
uhf connectors. i would also worry about high power rf through them. if
they are only for short term use and in a weatherproof enclosure and being
used for low power or just rx then there shouldn't be a problem.


Using 174 coax you do not have to worry about the power ratings of the
connectors. Some of the GE rigs used the RCA connectors at levels of 100
watts . The older Heathkit low band rigs used them on their 100 watt rigs.