PA0RDT Mini Whip Mods

I have carried out a number of tests on the MiniWhip ct. and like you, I
found that at +12V DC supply there were signs of inter-mod products - such
as weak phantom broadcast stations just below 400kHz which should not be
there

At +15 and above, they pretty well disappear.  I also then tweaked the
values of the 2.2K/10K potential divider feeding the base of the 2N5109 to
drop the base voltage a bit because with the original values, the
collector-base voltage was only about +2V which is not really enough I
think. I was also using about 150ft of 50 ohm RG58U coax to the shack from
the garden but with hind sight, I think it would be better to have used
70ohm feeder to reduce the capacitive load on the emitter of the 2N5109 and
probably insert a 70 ohm series resistor at the emitter to provide a better
source impedance for the cable and help absorb reflections back down the
line although would incur a 6dB signal loss.

73  de  Derek Atter G3GRO