Remote LNA Power
Remote LNA Voltage Drop Calculator
Your bias tee outputs a clean 12 V. The LNA at the far end of 100 ft of coax doesn't see 12 V — it sees whatever's left after the cable's own DC resistance eats into it. This calculator tells you exactly how much voltage actually reaches the LNA, and whether it's enough.
Bias Tee & LNA
Cable Run
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V at the LNA
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Voltage drop across the cable
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Power lost in the cable (I²R)
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Margin above minimum operating voltage
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Maximum cable length before brownout
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DC resistance figures are published inner + outer (shield) conductor values per manufacturer datasheets (Times Microwave LMR series; Belden 9201 for RG-58), summed as round-trip loop resistance.
Voltage drop = current × loop resistance × (length / 1000 ft). Assumes the DC path runs through the coax itself, as in a standard bias tee installation — not a separate power conductor.
Figures are planning estimates; conductor resistance rises with temperature and connector/contact resistance isn't included — verify against your actual components for critical installs.
Once you know what voltage your run actually delivers, pick the bias tee and LNA that work together on it.