Re: [IRCA] Need a radio reccomendation..

["Craig Healy" <bubba@xxxxxxxxxxxxxxxxxxxx>]

> 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@xxxxxxxxxxxxxxxx
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@xxxxxxxxxxxxxxxx