skipwave
Well-known member
I picked up a bargain bin tube amp with a nice Hammond power transformer, dual secondary 120V 75mA and 6.3V 1.5A, and a little output transformer that says 2.5K:3.2 ohms (no manufacturer just "JAPAN").
The two tubes on it are unmarked. Both are 7 pin. Based on the pinout the output tube is a 6AQ5. I can't figure out the first tube, but it is probably a medium to high mu triode.
Pin 1 is grid, Pin 7 is plate, Pins 2/5/6 are cathode (and whatever else you connect to the cathode resistor in this funky tube). 3 and 4 heaters, 6.3VAC. In the mystery circuit I'm looking at the cathode resistor is 2k2 and the plate resistor is 220k.
Plate out goes through a .01uF capacitor to a 6AQ5 power stage. The B+ is 120VAC through a 4R7 resistor, then half-wave rectified for around 160VDC.
I'll keep scratching my head and searching the web.
The two tubes on it are unmarked. Both are 7 pin. Based on the pinout the output tube is a 6AQ5. I can't figure out the first tube, but it is probably a medium to high mu triode.
Pin 1 is grid, Pin 7 is plate, Pins 2/5/6 are cathode (and whatever else you connect to the cathode resistor in this funky tube). 3 and 4 heaters, 6.3VAC. In the mystery circuit I'm looking at the cathode resistor is 2k2 and the plate resistor is 220k.
Plate out goes through a .01uF capacitor to a 6AQ5 power stage. The B+ is 120VAC through a 4R7 resistor, then half-wave rectified for around 160VDC.
I'll keep scratching my head and searching the web.