Hi Everyone! I am a first time amp builder with more digital experience than analog. I am building a Weber 6m45p kit and I am at the point of biasing the tubes. I am using the 1Ohm resistor method. The voltage on pin 5 of my power tubes start at 515V and as I watch the power across the 1Ohm resistor it starts a about 3mW, at around 7mW or so, it jumps to 11mW and it starts to squeal at a high pitch. From what I have read this is oscillation(?). Some of the methods I have read on line do not seem to fix my problem at all. I triple checked my wiring of the output transformer and all seems well. I am going to go over my wiring again to see if I missed anything. In the mean time, can anyone suggest tests, measurements, diagnostic things I could do to try to track it down? Thanks in advance. Links below:
http://taweber.powweb.com/store/6m45p_layout.jpg
http://taweber.powweb.com/store/6m45p_schem.jpg
http://taweber.powweb.com/store/6m45p_layout.jpg
http://taweber.powweb.com/store/6m45p_schem.jpg
This should be in the Instruments and Amps section.
Temporarily disconnect one end of R31, the feedback resistor. If this stops the oscillation then you have probably wired the OPT wrongly.
Temporarily disconnect one end of R31, the feedback resistor. If this stops the oscillation then you have probably wired the OPT wrongly.
I did have the OPT wired incorrectly. I swapped the blue and brown wires from the OPT to the EL34s and the oscillation stopped. Now I have a different problem/question, but I will take it to the correct forum this time. Thanks for your response!
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