rijo1 writes:

Thanks everyone for participating in this disscussion . This problem is in a
liniar amplifier . The plate that glows red is the driver tube . The tube is a
6LX6 and is not that expensive . The 4 driven tubes are 8908 tubes and are$
93.00 each . Anyway all the tubes are designed to have 6.3 v. to power the
filaments . Like I said , the voltage coming from the transformer is 7.2v.
These voltages were all checked on the bottom of the tube sockets .
I feel that being the voltage is so high on the filament that it is
making the tubes over conduct and saturating the plate .
I will buy a filament transformer and see if this clears the problem .

But was the voltage checked under load? Depending on the quality of the
transformer, a 0.9 V drop might not be out of the question when loaded
If this is the original transformers, failure with increased vcltage
is extremely unlikely.

The filament voltage on these types of tubes has virtually no effect on
operation as long as it's enough. That's not your problem. Current and
plate dissipation are determined by other factors.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.