Topband: Buffaloed by a bias tee

[Pete Smith N4ZR]

I'm still wrestling with the bias tee for my 1-of-8 remote beverage 
switch.  If I use a cliplead to connect a 270-ohm dummy load, bypassing 
the relay, and connect an MFJ-259B to the receiver port on the 
controller, the impedance looks completely reasonable - with a 3:1 
binocular transformer, 89 ohms R  and X=5, measured by the MFJ.  
However, as soon as I connect a 12V regulated supply to the bias tee - 
one of the little radio shack variable wallwarts - the measured R drops 
to 5 ohms and the X goes up to 19.

My history major's diagnosis is inadequate isolation between the DC 
supply and the RFline, but why?  The series RF choke in the DC line is 7 
turns on a ferrite core, measures 45 uH at 2 MHZ, and the bypass 
capacitor is a 0.01 uF disk, on thesupply side of the choke.  Theseries 
cap between the Antenna and the RX jacks on the controller is a .1 uF 
disk (it was what I had).  I do not yet have a safety choke between the 
RX side and ground, but will add one before I deploy it, if I can ever 
figure out what's going on.

I'd really appreciate some ideas of what to try.  Thanks in advance!

-- 
73, Pete N4ZR
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