4K7 OPT suitable for 6550/KT88?

[Miniwatt]

L.S.

I've got some 4K7 output transformers I'd like to use for a SE 6550 project.
I've been fiddling with load lines, and came up with this:

My gut feeling would like me to use a steeper line, is this advisable? I'll use more current anyway, but the xformers are really good 🙂

Thanks!

 

[hemgjord]

What is your B+ voltage.
From the load lines it seems like around 250V. It's pretty low....
With a load of 4k7 I would suggest a quiesent point at approx 400V 80mA
Should give you approx 7W

/Olof

 

[Tubelab_com]

I've got some 4K7 output transformers I'd like to use for a SE 6550 project.

I have build Simple SE's with 3K, 3.6K, 5K, and 6.6K OPT's. I like 5K the best but I run about 460 volts of B+. About 40 of that is dropped in the cathode bias resistor, and another 10 in the OPT, so the tube sees 400 to 410 volts.

 

[mace1337]

Care to share what trafo's they are and where you got them? 🙂

 

[Miniwatt]

Care to share what trafo's they are and where you got them? 🙂

Most won't know them, but you might😉 I got them from a Aurexx Crystal 1 amp, a SE EL84 thingy. I'm pretty sure they can handle the power, they are BIG!

I planned to use the power tranny from a Bocama LA 224B, but dropped the idea, I would like some more volts and amps, haven't decided yet though..

 

[mace1337]

Oh yeah I know those.
I need to get me a Lafayette or Bocama too for a EL84 I'm planning to build, but my 6L6 comes first.

Hmm, using a 3.5W EL84 OPT for a 10W-ish KT88.. Good idea? 😉

 

[Miniwatt]

Hmm, using a 3.5W EL84 OPT for a 10W-ish KT88.. Good idea? 😉

Someone knowledgeable suggested I use those Bocama trannies for 6550, they could handle the power. In that case my SE trannies probably will do fine, it's about double the power, not times ten.. We'll see/hear it, right? 😉

 

[mace1337]

Sure, sure, just putting it out there! 🙂
I eagerly await the results.

And if you have a line on cheap bocama/lafayette OPT's let me know. 😀