BluegrassDan said:And 3D.
Thanks, everyone, for all the help. I'm new to PCB design. This is just my second board.
BluegrassDan said:One more "FINAL" version. Needed to clean up the silkcreen and add two more mounting holes halfway.
You can't replace 66k/4W resistor with two 33K/2W. Anyway you don't need so low values of these resistors just for heater bias.BluegrassDan said:R9 and R10 are two voltage dropping resistors, dividing 66k @4W between two 33k @ 2W resistors.
It looks good but I would put a small heatsink on it.D6 is a GBU802. 8W, 200V. https://www.mouser.com/ProductDetail/Diodes-Incorporated/GBU802?qs=sGAEpiMZZMtQ8nqTKtFS%2FJolQOfQMTyVY01irg1iCuA%3D
BluegrassDan said:Please help me understand ground planes. How would it help this design?
moamps said:You can't replace 66k/4W resistor with two 33K/2W. Anyway you don't need so low values of these resistors just for heater bias. It looks good but I would put a small heatsink on it.
Yes, they can. My bad. I didn't decoded this part of the board correctly. Could you post the schematic of the whole power supply?BluegrassDan said:Am I undermisstanding? Two 33k 2W in series cannot replace a single 66k 4W?
Many tubes specify no more than about 20K resistance between heater and cathode. 66K and 22K give 25% HT heater elevation.moamps said:You can't replace 66k/4W resistor with two 33K/2W. Anyway you don't need so low values of these resistors just for heater bias. It looks good but I would put a small heatsink on it.
ruffrecords said:Many tubes specify no more than about 20K resistance between heater and cathode. 66K and 22K give 25% HT heater elevation.
The resistor value is the same no matter how many tubes, The bottom resistor is always decoupled by an electrolytic so that at ac the heater and cathode are connected directly together.moamps said:Does this resistance should have the same value if one or more tubes are connected to the one heater power supply? What happens if this resistor is shunted with a capacitor? Is resistance Rhk always equal to Rh-ground?
Btw:
(Designing High-Fidelity Valve Preamps by Merlin Blencowe)
ground planes
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