Right then. I've got most of the Parts in stock to build the modders delight version.
I'm just struggling to get the 2 watt 18r resistors. I can find 3 watt 18r resistors, can I use these?
I can also get 1.6 watt 18r resistors if that's any better?
Also what values should I be experimenting with r13a?
And finally where in the UK (Lincolnshire) are you getting the d bar handles to protect the tubes?
I can't find any anywhere near small enough.
Thanks in advance
3 watt is just fine (better even if it fits your case) , 1.6 watt may work but you need to do the math, rick is dropping about 5.7 (12 - 5.7 = 6.3 volts, what the these tubes like on their heaters) volts so ohms law says V = I *R or V/I = R in this case, according to the datasheet the heater will pull .3 amps
Rick got 18 ohms I assume from doing the math of dropping 5.7 volts = 5.7/.3 = 19 ohm (18 is close enough and probably the closest standard value)
using what we have v = I * R or V = .3 * 18 = 5.4 volts
to find wattage ,there are a few formulas but this works
Watts Law Power = Voltage * Current
5.4*.3 = 1.62 watts
The other way is P = I^2 * R
.3^2 * 18 = 1.62 watts
so all of that to say 1.6 would work, but you would be at the limit of that resistor and could have issues, It a rule of thumb to go x2 as big, Rick decided that 2watts was enough and it works for him every time as far as I know.
hope that helps