Retired after 40 years in business
 and 60+ years of broadcast engineering 

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Technical Tips from Mark W. Persons
BE FM 25T Transmitter work

April 1, 2009:  Here is your intrepid engineer Mark Persons working on a Broadcast Electronics FM 25T Transmitter before retirement.       

On this day, a failed bypass capacitor (at the bottom left) of the power amplifier cavity caused the transmitter to shutdown.  This capacitor is in the PA screen supply that typically runs about 600 VDC.  Turning the screen power supply breaker off allowed the transmitter to run at about 20% power.  Going to full lower on the screen control allowed me to bring the transmitter power up slowly to about half power.  Then the capacitor started arcing, causing the transmitter to again shut down.  Once the problem was found, the plan was to replaced the defective feed-thru with a temporary one until a permanent replacement arrived.  The capacitor is rated at 2500 Volts.          

The stories go on and on.  Stop in again sometime.  I'll leave the soldering iron on for you. 
Mark W. Persons   ham W0MH      

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