05-22-2022, 05:38 PM
It also cautioned against using too high of wattage ratings?
The higher the wattage the larger the physical size so some times it's a matter of will it fit. The larger the wattage the better it can dissipate heat. In circuits like power supplies higher wattage resistor are common. In low level signal circuits like rf amps, mixers, IF amps, and such they aren't necessary. Pretty much 1/2w is the standard.
How do I determine the rating?
What I do is figure the current flow thru the resistor. Do rough calculation of the tubes vs the current they draw. Came up with 45ma and the high voltage at 250v. If you know the voltage on both sides of the field coil you can you use that to figure the current of the set.
I came up with 180 ohms @ 1w 3500 ohms @20w and 60 ohms @ 5w
The higher the wattage the larger the physical size so some times it's a matter of will it fit. The larger the wattage the better it can dissipate heat. In circuits like power supplies higher wattage resistor are common. In low level signal circuits like rf amps, mixers, IF amps, and such they aren't necessary. Pretty much 1/2w is the standard.
How do I determine the rating?
What I do is figure the current flow thru the resistor. Do rough calculation of the tubes vs the current they draw. Came up with 45ma and the high voltage at 250v. If you know the voltage on both sides of the field coil you can you use that to figure the current of the set.
I came up with 180 ohms @ 1w 3500 ohms @20w and 60 ohms @ 5w
When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!
Terry
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