View Single Post
  #18  
Old 07-12-2006, 06:09 PM
matt_s78mn's Avatar
matt_s78mn matt_s78mn is offline
VideoKarma Member
 
Join Date: May 2006
Location: Lincoln, NE
Posts: 314
Quote:
Originally Posted by wa2ise
The rectifiers in most of those used to be mercury vapor and likely been replaced with solid state rectifiers.

Maybe the old transmitter has an input jack for a microphone. With a tube preamp?

And how many people will have vacuum tube portable AM radios with fresh batteries? I would assume that the poweline would be dead.
Judging from a majority of the AM and FM transmitter sites I have visited, if the older transmitters are kept for backup, generally their exciters are replaced by modern solid state equivelants. One of the more interesting AM sites I've been to had three transmitters, all of them still operational. The oldest one was an RCA, it was from the 1930's, and had very cool art deco styled cabinet. It had a door with a small glass window, where you could look in and see the IPA tubes, and their blue glow modulated along with the audio. The second was a mid '60's Gates, and the third, a modern Harris DX-10 solid state transmitter. They brought the RCA transmitter online every couple months or so, just for the fun of it.

Also, I remember a college professor of mine talking about this very issue of what would happen to the solid state equipment, and he stated that equipment could be protected from the pulse if it was enclosed in a "faraday cage," which is a type of RF shielding.
Reply With Quote