Lee K7TJR wrote:
>
> Interestingly enough, one of the claims on the
> Rauch/DXEngineering patent on the active antenna 4-square
> receiving system is that resonating the DC carrying chokes
> across the output common mode isolation transformer in an
> active antenna amplifier increases the common mode
> rejection. I would like to see how that works with an amplifier
> that covers many octaves of bandwidth and a resonance being
> usually fairly narrow band. Anybody know how that works at
> more than one narrow band of frequencies?
I haven't read the patent, but I did purchase a couple of
these for evaluation and trace out the schematic. The INPUT
has a resonating system using jumpers to select the frequency.
This is a shunt tank that will do nothing to prevent feedline
pickup.
I don't remember seeing any resonating capacitors across the
DC chokes, but as you say, it would be a narrow band solution.
I tried to make a dipole from two of the DXE units and found
that the feedline pickup made it unusable. In my homebrew
receiving dipoles, I only use transformers to decouple the
feedline. Of course I can do that because I don't have to convey DC,
since I don't use preamps at the antenna.
Rick N6RK
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