Topband: bias tee

[donovanf at starpower.net]

Hi Pete,

You can use your MFJ 259 to measure loss through your bias-T setup.   

100 microhenries should be adequate; however, a properly designed bias-T should always have  two inductors at the injection and and two at the far end of the coax cable.   The series inductor isolates the power injection port from the RF path and and an inductor to ground protects the RF electronics (preamps and transceivers) from damage if the series capacitor feeding that port should short.

My bias Ts use simple homebrew inductors, just a few turns of wire on a ferrite core.  Use your MFJ-259 to optimize the inductors.

73
Frank
W3LPL

----- Original Message -----
From: Pete Smith N4ZR <n4zr at contesting.com>
To: Topband at contesting.com
Sent: Thu, 14 Nov 2013 07:58:47 -0500 (EST)
Subject: Topband: bias tee

I am using my coax to feed 12 VDC to my remote RX antenna locations, 
using a traditional bias tee, but am having some trouble with 
performance. I'm using 100 uH Radio Shack chokes in my bias tee, and am 
wondering if perhaps that is insufficient inductance for 160 meter 
operation. If so, what would be an appropriate value?

-- 
73, Pete N4ZR
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