November 2009
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What the inside of a ceramic vacuum tube looks like

In case you have wondered it yourself:



This is an EIMAC 4CX3500A which came out of a Harris HT5 transmitter. As you can see it the ceramic cracked in half. When I arrived at the transmitter site, the unit was on, full plate voltage, no plate current, no overload lights. I figured it might be something with the tube, so I tried to pull it out, but only the top half came. One of those “Ah ha” moments.

Fortunately, there was a working spare at the transmitter site and we got back on the air relatively quickly.  That, in and of itself is amazing considering the building that this transmitter lived in.  One of those abandond former studio sites with the transmitter jammed into a back room somewhere.  To get to it, one has to dodge pigons, beware of rats and wade through piles of garbage.

It is a little bit hard to tell in this photograph, but there are to “cages” which are the Screen and Grid.  The post in the center is the filament/cathode and the top detached part is the plate/anode.  In an FM transmitter, the exciter is coupled to the grid, the screen accelerates electrons toward the plate and therefore controls the power, the plate collects the electrons and is coupled to the output stages and the antenna.  Good stuff.


A pessimist sees the glass as half empty. An optimist sees the glass as half full. The engineer sees the glass as twice the size it needs to be.

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution

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~Benjamin Franklin

The individual has always had to struggle to keep from being overwhelmed by the tribe. To be your own man is hard business. If you try it, you will be lonely often, and sometimes frightened. But no price is too high to pay for the privilege of owning yourself.
~Rudyard Kipling

Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19 was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner

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