After replacing a burned out FM antenna for one of our clients, the question became; what do we do with the old antenna? There were several options:
Throw it behind the transmitter building and let weeds and poison ivy grow over it
Take it to the scrap yard to get what ever money we could for it
Give it away to somebody
Turn it into a fountain
I have scrapped these old antennas before, they are made mostly of hard yellow brass, which does not net too much at the scrap yard. In fact, by the time I finished removing the Radomes and separating the metal, I had more time into the job than it was worth for both myself and the client. Therefore, I present to you the ERI LPX lawn fountain:
Upon completion, my wife and daughter, who are natural born skeptics, even had kind words to say. It seemed like a simple project at first; enlarge the dry well for the basement sump pumps and install some type of mounting base for the old antenna. It turned into a little more than that.
It took several hours of backbreaking labor, a concrete form and a few bags of ready mix concrete to create the mounting base. Several wheelbarrow loads of gravel, some rocks from the old wall in the woods and a pond pump from the hardware store round out the installation.
Not related to radio, but interesting nonetheless. Mozilla, the designer of the Firefox web browser has come up with a cool way to see tracking data for any HTTP sessions. It is an add-on called Lightbeam. I tried a little experiment, after installing lightbeam, I surfed around a little bit then looked at the results. A screenshot of the graphical output is below:
The round circles are the sites that I visited. The triangles are third party sites connected to the visited site. During the real Lightbeam session, a mouse over the icon will show the name or url. It is an interesting exercise. Visiting 27 web sites nets a total of 172 third party sites or approximately 6 third party sites per visited site. Commercial news sites like CNN and NBC seem to have the most connections to third party sites. In this case, it appears to be mostly innocuous advertizing. Even so, it is an enlightening experiment.
It’s a cute little thing. These were often used for driver tubes in FM broadcast transmitters. With the naming conventions of ceramic tubes, we can tell quite a bit about the unit without even looking at the data sheet.
The first number is indicates the number of grids in the tube, 3 makes it a triode, 4 tetrote and 5 pentode.
The C means it is a ceramic tube
The X indicates it is air cooled, a V is vapor cooled, W is water cooled, M is multiphase
The 250 is the plate dissipation is watts
B is the design revision.
Thus a 4CV100,000 is a vapor cooled tube capable of dissipating 100,000 watts, something one might find in a high powered MF or HF transmitter.
Other bits of critical information about tubes would be maximum plate voltage, maximum screen voltage, maximum grid voltage, maximum screen dissipation, maximum grid dissipation and filament voltage. Something to keep in mind when tuning a transmitter.
This particular tube is installed in the driver section of a Continental 816R2 transmitter.
I have noticed that these tubes have a much shorter life than there predecessors. Back ten or twenty years ago, they usually lasted 12-14 months. The latest set lasted only 8 months and both units failed catastrophically. That points to one of two things; either something in the transmitter has changed or something in the way the tubes are manufactured has changed. Once the new tubes were installed, I checked all of the parameters against previous maintenance logs. I also checked things like air flow, dirt and other possible culprits.
I could find no changes in the transmitter. The only thing I can think of is the fact that the tubes are installed horizontally, which causes the elements to warp and eventually break or short.
I am thinking we may try to convert the driver section of this transmitter to a solid state unit. The transmitter itself is 24 years old, but is still works and sounds great. I’d hate to get rid of it because of its driver section.
Yesterday, January 18, 2012, I blacked out engineeringradio.us for the day in protest of the internet censorship bill working its way through congress colloquially known as SOPA or PIPA. There were some 17,000 or more others that did the same.
If the internet is indeed the new media, destined to replace the old media, then having in place draconian restrictions that allow the government to block websites and content with no due process for the website owner is censorship, plain and simple. Imagine a country where the government can come in and shut down any newspaper, TV station or Radio station, give no reason other than some weak statement about copy write laws. See also: China, North Korea, Cuba, Soviet Russia, etc.
It is important to check the corporate power in this country. It is widely reported that Congress has a 9% approval rating. It is also hard to imagine their approval rating is actually that high. While signing petitions and writing senators and congressman may provide some relief, the shortest path to ending this is to boycott the corporate sponsors of the legislation. Hitting companies bottom line will speak louder than any internet protest, petition, letter writing campaign, etc. Thus, if so inclined, here is a list of producer companies that like the idea of internet censorship.