> I'm looking mainly for something to use once we're off the air here at > 1590..... no matter what kinda radio I have, it'll overload here
I have done a fair bit of work with DXing right at transmitter sites. The Palstar R30CC is quite robust. I have used it about 30' from a tower with a kilowatt into it without trouble. I've also strung out a 950' BOG about 400' from that tower and found it OK. Once I set a copper loop about 20' from the tower and phased it against the BOG to null the station. It works if the phaser is robust enough. I made a passive phaser with large toroid cores for inductors that were saturation-resistant. A simple loop like that copper tube type can null out a tower to easily DX more than 20-40KHz from the station frequency. For some places I have made up a two-stage notch filter that goes in the antenna lead. Down at 550KHz it drops that maybe 40db. Higher up around 1340 it pulls it down maybe 25db. Gets rid of the overload artifacts. I also did one experiment with hooking a resistor isolator right to the transmission line to the tower and running it to a receiver through a tuner with the station on the air. That did work, but a broadcast tower is generally not a great receive antenna. Picks up too much noise, and the omnidirectional pattern generally isn't what you want. In 1970 I did hook up one of the 400' towers at WSAR-1480 to an old Hallicrafters receiver after signoff. Got WQAM-560 with a good signal. Never heard that station again. Don't give up on DXing at a transmitter site. Except right near the station frequency or a harmonic, there's a lot to hear. There are more than a few tricks you can use to null out the local signal, even when it's at a huge level. Next project is to use the resistor pickups on two towers and phase them. I'll try that on the 550 station. Two 300' towers about 300' apart. The resistor pickups prevent the receive part from having any effect at all on the transmitted signal or readings. Craig Healy Providence, RI _______________________________________________ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
