[BC] am receiver for monitoring at a 20 KW site.

[Craig Healy]

> Can anyone recommend a reasonably priced AM receiver that
> can set at a 20 KW AM site and monitor a 5 KW AM station
> about 1.5 miles away without having a lot of bleed through?

The Palstar R30A is a very robust receiver.  I have an older version in my 
truck.  Parked about 50' from the tower of a kilowatt station, I can adjust 
a combination of antennas to null that station well enough to hear the 
adjacents.  The Palstar seems to have better survival of strong signals than 
most any others I've tried over the years.  But, with that antenna system, 
almost any decent receiver could work.

The antenna is a combination of a large ferrite loop and a vertical.  By 
combining them through a potentiometer-based transformer, it can null the 
undesired station quite far down.  http://www.am-dx.com/simple_phaser.htm 
All that is needed is adjusting the potentiometer level of the vertical 
antenna for the ratio, and turning the loop for the phase.  It's quite 
stable for local stations to null.

If a large ferrite loop isn't desired, a simple copper tube loop would work 
equally well.  The one pictured has two outputs, but only one would be 
needed.  http://www.am-dx.com/loopant.htm  I compared it directly to a well 
known commercial antenna and it actually worked a bit better.

The vertical antenna was simply 50 feet of wire wound around a 2" PVC tube. 
There was a 450:50 ohm balun in the middle.  Cheap and easy to build. 
http://www.am-dx.com/vertical.htm

Over the years it has been very handy for tracking intermodulation as well 
as monitoring.  I set up something similar for an EAS receiver.

If a preamp is necessary, this has worked the best for my applications.

http://www.dxengineering.com/Parts.asp?ID=210&PLID=107&SecID=32&DeptID=12&PartNo=DXE-RPA-1

Craig Healy
Providence, RI