TubelabSE 45: PT, choke and C4 questions

[dth31]

I'm about halfway thru my first Tubelab SE project--will build the 45 version. I have several questions.

1. Which power transformer?
I have a Hammond transformer on hand (270HX; 275-0-275 @ 230 mA; 2.5-0-2.5 @3A; 3.15-0-3.15 @6A) but I'm afraid the B+ will be way too high (I would prefer to run the 45 cautiously at around 280V and 27 mA). Would appreciate advice. I know that it's over-spec'd, but might the Edcor XPWR093 (250-0-250 @300 mA; 3.15-0-3.15@7A; 5V@5A) work better? If I need to, I could order a custom power transformer from Heyboer--they quoted me a 2-3 week wait, while Edcor was more like 8-12 weeks.

2. Power supply: changing R4 to a choke and C4
I'd prefer to use a choke in place of R4. I can order either the Hammond 158M (10H; 100mA; 262 ohms) or the Triad C-14X (6H; 200mA; 150 ohms).

If someone has experience as to which combination of power transformer, choke and C4 yields B+ around 280-300V, I would be most grateful to hear your recommendations. Many thanks!

 

[rknize]

The Edcor is a better choice there. The Hammond 370JX is another candidate, though it would probably come in higher than spec.

For the choke, the 158M would be overloaded a bit. The 159P would be a better choice, but you can't beat the price of the Triad C-14X.

 

[dth31]

Thanks Russ. As the "iron" are the most expensive parts for my build, I was trying to get things "right" from the beginning.

 

[rknize]

I should point out that Edcor is build-to-order, even if you use an existing design.