The NPR article mentioned that as parts broke down, they were 
replaced with what was available and power was lowered over time.  I 
wonder if X E R F is still out there in a diminished way?
Pat, K9JAUAt 03:28 PM 1/24/2011, you wrote:
>         I am not surprised. That is just a lot of power any way
>you look at it.
>
>         When XERF first came on in the thirties, the transmitter
>tubes had to be specially ordered. The transmitter was
>water-cooled. I wonder, back in the late sixties or seventies,
>if when the US and Mexico negotiated a better broadcasting setup
>for the AM band, they just turned down the screen voltage on
>that monster and kept it loafing along on 50,000
>Watts. Just think, that transmitter was designed to put out
>500,000 watts all day long so it probably could do 50 K for the
>next 75 years and just get a little dusty.
>
>         Seriously, it was probably full of PCB oil and hard to
>keep going so they probably just scrapped it and bought a modern
>transmitter.
>Pat Byrne writes:
> > martin,
> > I also heard on an old NPR broadcast that XERF would bring close
> > flying birds out of the sky to their demise.  And I believe, in their
> > heyday there were a number of "super power" stations just across our
> > southern border.
> > Pat, K9JAUAt 12:00 PM 1/24/2011, you wrote:
> > >         I recently finished reading a book about one of the
> > >biggest medical fraudsters in US history who snake-oiled his way
> > >to riches during the 1930's in the United States and then from a
> > >powerful AM radio station on the Mexican border. His name was
> > >John R. Brinkley and he called himself a physician though he had
> > >no valid medical degree.
> > >
> > >         Most of the book is not directly radio-related, but
> > >there is a brief description of Brinkley's Mexican boarder radio
> > >station which later became XERF and I am sure some of you
> > >remember the preachers selling all kinds of stuff that one could
> > >hear after dark on XERF.
> > >
> > >         XERF's transmitters were just across the river from Del
> > >Rio, Texas and, at one time, were 500,000 Watts directional in
> > >to the United States.
> > >
> > >         People report that at night, the antenna towers arced
> > >with green flashes. XERF leaked in to telephones in town, could
> > >be heard on things that weren't even electronic such as bed
> > >springs, and made the headlights of cars come on even when they
> > >were supposed to be off as they drove around town.
> > >
> > >         XERF transmitted on 735 KHZ in the mid thirties and many
> > >of the radios were TRF or Tuned Radio Frequency receivers. These
> > >were the predecessors of the superheterodyne radios we are more
> > >familiar with. In a TRF radio, you have 1 or more tuned circuits
> > >which you peak and tweak until they are centered on the
> > >frequency of the radio station you want to listen to. There is
> > >no IF, no conversion, no nothing; just tuned tank circuits of
> > >sometimes dubious Q factor between the antenna and detector.
> > >
> > >         If you ever had a crystal radio or have seen an old
> > >radio from the early part of the last century, it was a TRF.
> > >
> > >         In the 1930's, XERF had such a power-house signal at
> > >night that people trying to listen to other radio stations in
> > >other parts of the AM band suffered interference from Brinkley's
> > >transmitter no matter where they tried to tune.
> > >
> > >         It was a combination of tremendous AM transmitter power
> > >coupled with basically poor quality receivers.
> >
> >