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Discussion in 'Amplifiers' started by Number15, May 25, 2007.
__________Warning, there is 800 VDC in that thing, it will not kill you but it will spoil your day!_______________
You have the Palomar 200X, the one with the 6LF6s driven by the 6JB6. There are a couple of things that could cause your amplifier to act like that.
First, you ask as to whether or not you can change the value of the filter caps in the HV powersupply. Yes, you can put in 220 uf at 450 vdc caps; stick to the same form factor (shape and size). When filter caps go bad, you know it because they "bust" and the oil insulator jets out and they smell really bad. I would suspect them only if the high voltage on the plates of the tube is dropping severly under load, you had an explosion in the amp or, you are getting reports of AC hum in your transmission.
I think if I were you, I might check to see if it is dropping power in both the Hi position and the low power side. There is a 1.8 K ohms resistor on pin 2 of the driver tube, there is also a 1.8K on pins 5 / 9 of the final check that also; those resistors form your bias circuit.
When your power drops, are you able to recover it by retuning? There are 2 DC blocking / RF Coupling caps (.002 uf at 2000 volts), if either of those are changing with temp, your power out will change.
Let me know what you find.