Almost Eighteen Years

I do not know what the record is for the longest tube life, however, this particular tube lasted 17 years, 11 months and 23 days.  That’s 157,596 hours.

I had written about this almost five years ago: http://www.engineeringradio.us/blog/2014/12/longest-tube-life/

The last one was last fall: http://www.engineeringradio.us/blog/2018/09/i-almost-hate-to-say-anything-but/

Eimac 4CX12000A power tube

This was installed new in a Broadcast Electronics FM20T transmitter which was placed on line on June 6, 2001.  It lasted until May 28th, 2019 with almost no down time.  Towards the end, the emissions started dropping off and we increased the filament voltage up to 10 volts.  When you have to increase the filament voltage, that really is the end for a tube.

The new tube was put in and I carefully marked out the date in the maintenance log.  The hour meter on the transmitter stopped working several years ago.

Prior to this, the longest tube life I’d experienced was an EEV 4CX35000C from an MW-50B transmitter RF section.  When that tube came out, it looked like it have been on fire.

2 thoughts on “Almost Eighteen Years”

  1. The tube I just pulled out of a HT-10 didn’t look that pretty. It was an Econco rebuild that lasted 2 years 10 months of 24-hour operation. It was chocolate brown, instead of cafe-au-lait as usual, but it did get abused by a failing PA blower and a winter where it ran weeks at low power into an ice-encased antenna. The previous rebuild got 4 years of life. As I commented in earlier posts, the FM20T I care for has used two tubes in 15 years. I don’t know if tube number 3 will live that long…it was treated to a bullet burnout at the antenna a year ago.

  2. Belated welcome back Paul and happy 18!
    How did the rest of the transmitter’s components fare at the tube change? I predicted some funky stuff in lower PS areas.Perhaps you were lucky,hope so!

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