You are not looking at the power settings. You need to measure the voltage across every single tap of the primary. From there, you choose the one with the correct impedance for your tube... this may be any of the taps that may be smaller than 10W...
FingerBoy: The Edcor XSE or GXSE transformers are both excellent choices. The 10W XSE's are $17/ea and the 15W XSE's are $20/ea. They are naked, ie no end bells. The GXSE 10W units will set you back about $60/pr shipped and have end bells and slightly wider BW. The 15W GXSE units are about $80/pr shipped. They all have a 4-6 week lead time, so plan ahead.
I have decided that I would like to explore this design.
I have gathered all of the components necessary except for OPTs, tubes, tube sockets, and the chassis.
Should I assume that all resistors should be 1/4W unless stated otherwise? Most of the ones I got were 1W+, but some seem to be 1/4W. I can't tell the power rating.
The one I'm unsure of is grey and feels more coarse but looks just like a carbon-composition resistor. It's 8mm long (6mm 1st band to last band) and 2mm in diameter. It looks to be a 1/4W. I assume it to be metal film.
I used 7W resistors when they called for 5W, but it says on the data sheet: Limiting Element Voltage 200V. Bad news?
I have gathered all of the components necessary except for OPTs, tubes, tube sockets, and the chassis.
Should I assume that all resistors should be 1/4W unless stated otherwise? Most of the ones I got were 1W+, but some seem to be 1/4W. I can't tell the power rating.
The one I'm unsure of is grey and feels more coarse but looks just like a carbon-composition resistor. It's 8mm long (6mm 1st band to last band) and 2mm in diameter. It looks to be a 1/4W. I assume it to be metal film.
I used 7W resistors when they called for 5W, but it says on the data sheet: Limiting Element Voltage 200V. Bad news?
If it's for the 270 ohm cathode resistor it's ok, if for some reason it sees that voltage it's better it blows!......
Oh cool! Yes, it is for the cathode!
GOOD LUCK !!!
The grey rough Resistor sounds like a MOX (Metal Oxide).
Using higher wattage resistors are not a problem. If you are doing point to point, larger resistors actually make it easier to wire up/solder, especially if you've got clumsy fingers like me.
Now is the waiting for the parts to arrive. Don't worry, they will arrive soon enough. The circuit is simple enough you can breadboard it in an hour for testing. If you do not have a chassis planned, maybe you can start off with that. Look for the Morgan Jones book on how to layout a suitable chassis.
GOOD LUCK !!!
The grey rough Resistor sounds like a MOX (Metal Oxide).
Using higher wattage resistors are not a problem. If you are doing point to point, larger resistors actually make it easier to wire up/solder, especially if you've got clumsy fingers like me.
Now is the waiting for the parts to arrive. Don't worry, they will arrive soon enough. The circuit is simple enough you can breadboard it in an hour for testing. If you do not have a chassis planned, maybe you can start off with that. Look for the Morgan Jones book on how to layout a suitable chassis.
Thank you! I really like the look of symmetrical designs. I also have a pre-drilled board that I may use. Is PTP still good design practice? I want to keep the price way down, so I can't afford to design PCBs for it. I have a decent amount of experience with PCBs, but I have no experience with PTP. It can't be that hard..
Not sure what choke your planning to use but IMHO the 20H choke could be replaced by a smaller one, say 10H. I think it should be rated at 100ma instead of 50ma if it is to remain effective.
Point to point wiring is " easy peasey "..............
I have (2) 15H, 40mA chokes and (2) 5H 100mA chokes. The 40mA worries me, so I should probably use the 5H 100mA chokes?
You've got them so why not use them.....
I thought the 15H would make a big difference, but they are kind of useless for this project it seems. Unless I use them elsewhere.
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