[IRCA] Ad hoc phaser

["Craig Healy" <bubba@xxxxxxxxxxxxxxxxxxxx>]

I had a some time tonight, so I thought I'd try phasing two loops.  One is a
copper tube loop of 30" on a side.  It is just leaning up against the desk.
The other is that big ferrite bar loop I showed in a previous email.  This
has a rotating mount.

I had made a combiner for another project.  It was simply two 1000 ohm
conductive plastic linear pots in a sealed metal box.  There are two input
SO-239 connectors, and one out.  Nothing to it.  One antenna was connected
directly to it, and the other was connected to a simple LC antenna tuner I
built 25 years ago, then to the combiner.

In use I use one loop to null the undesired local, in this case WSKO-790
which is the strongest local here.  Once nulled, I used the other loop and
tuner to provide an out of phase trim signal to deepen the null.  I was able
to bring WSKO down so I could hear another station playing slow instrumental
music.  This is a big improvement over anything I've tried here before.
Adjacents WBBM and CKLW were very good, and several S units higher than the
nulled WSKO.  The null has been pretty stable, too.

In fairness, I have not tried doing this using my new Quantum phaser.  That
will be next.

What I wanted to prove is that it doesn't take much to build an effective
phasing setup.  What I found was two loops at 90° to each other can be very
effective.

I suppose next I need to add a 180° transformer and switch to the combiner.
Then, build a multi-stage phase tuner in a shielded box.

Craig Healy
Providence, RI



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