Longevity

One of the stations that we do contract work for installed a Broadcast Electronics FM20T transmitter on June 6, 2001. It is still running on the original tube, a 4CX15,000A. By my calculations, that is 11 years, 7 months and 9 days, or 101,712 hours.

Broadcast Electronics FM20T transmitter
Broadcast Electronics FM20T transmitter
BE FM20T filament meter
BE FM20T filament meter

The hour meter shows 101,168 hours, which accounts for some maintenance, and other anomalies.  Overall, the transmitter has a 99.5% up time. I do not think the transmitter suffered any failures, rather, things like the generator and the STL failed instead.

EIMAC 4CX15000A tetrode
EIMAC 4CX15000A tetrode

Almost twelve years on one tube is pretty impressive.  I know that other Broadcast Electronics T model FM transmitters have similar tube life expectancies.  I wonder what the Broadcast Electronics secret is.