75x34x151mm Approximately...Big! They are cheap as heck, I got them for less than 5$ each. And they last forever in tube amps like this. But, they last for the same reason that they are so huge....
They are rated for 100A...
I've used them in a couple amps where space wasn't an issue, but they're just too big for most things. Especially amps like this where lots of room is taken up by the already large components needed for the transmitting triodes....
Loren
They are rated for 100A...
I've used them in a couple amps where space wasn't an issue, but they're just too big for most things. Especially amps like this where lots of room is taken up by the already large components needed for the transmitting triodes....
Loren
I have enough room for them 😉
Do you have a link or something from where you got them?
Regards
yeah I'll search them out and post it for you, EBay, and the sellers will take far less in the buy it now auctions....not like these are hot tickets, they're just glad to get them sold...I'll get it up here
Deal. Post a picture or two so I can google them, see their specs.
I'm waiting for Bosch MP 16uF 1.6kV/2.4kV PIO caps. They'll be a tight fit, but I have to have something in reserve. 😀
What about Wima caps? I haven't seen that they have HV caps with so much capacitance.
https://www.digikey.com/product-detail/en/epcos-tdk/B32778G1276K/495-3933-ND/1884954
4.5 mOhm 2.264" L x 1.378" W (57.50mm x 35.00mm) 27uF x 1300V DC
$14.48
4.5 mOhm 2.264" L x 1.378" W (57.50mm x 35.00mm) 27uF x 1300V DC
$14.48
Voltage rating minimum 1.6kV. Operating point in my amp is 1220V 80mA, so 1300VDC caps aren't enough. I don't want to connect caps in series. 😱
Kb2wyl, when you have the time, post what caps you have.
Regards
FYI
I am building one of these. I got my output transformers from SAC Thailand. He was mentioning he makes a coupling transformer with two secondary windings just for this application, so you can adjust the bias on your GM70's separately. Just shoot him an email. The address is on the SAC Thailand site if interested.
I am building one of these. I got my output transformers from SAC Thailand. He was mentioning he makes a coupling transformer with two secondary windings just for this application, so you can adjust the bias on your GM70's separately. Just shoot him an email. The address is on the SAC Thailand site if interested.
Ok. I was wrong about the voltage, I thought they were 1.6kv...Turns out they're 1.3kv. Should still be fine though, I'm sure they can take all 1300v all day, they're extremely industrial. I used the 800V versions on an amp with 675v B+ and they weren't even warm to the touch after hours of use.
Anyway, the label on them is this:
Thompson-CSF
FSM26-9184--B
20uf +- 5%
1300V 50 A (the 900V ones I have are 40uf and 100A)
JO
Seems that when I ordered them off of E-bay I remember them being listed as a different name? It was a couple years ago...if you search for film capacitors and high voltage, you'll probably find something similar...let me know if you still need a pic.
Loren
Anyway, the label on them is this:
Thompson-CSF
FSM26-9184--B
20uf +- 5%
1300V 50 A (the 900V ones I have are 40uf and 100A)
JO
Seems that when I ordered them off of E-bay I remember them being listed as a different name? It was a couple years ago...if you search for film capacitors and high voltage, you'll probably find something similar...let me know if you still need a pic.
Loren
Look at my attachment. I can't risk 1.3kV caps if my peak voltage is over 1.3kV. Safety first. We're talking about voltages way above 1kV.
I'm looking to make a reserve, so I don't have to thing about HV caps again 😀 😛
Look at pic #2 in attachment. That's the capacitors I'll install in my amp with 5H 150mA chokes.
Thanks again for your help.
I'm looking to make a reserve, so I don't have to thing about HV caps again 😀 😛
Look at pic #2 in attachment. That's the capacitors I'll install in my amp with 5H 150mA chokes.
Thanks again for your help.
Attachments
Oh, don't get me wrong I agree with the safety. I wouldn't have mentioned them in the first place but for the fact I thought they were 1.6kv. I think you should still look them up, see what you can find out from there as far as what is offered in the next voltage up. One spot where they would come in handy would be as first cap. Series would give you 10uf and 2.6kv...well not YOU, just saying...But really I'd bet there are higher voltage offerings from them. Being thin film, I do like their sonic characteristics.
I was just figuring you were probably down more around 11-1200v. Even at 1200V, I would certainly trust these. Yes there is instant on spike, but look up data sheet, I bet even the 1.3kv ones could handle that. Also, you can get rid of a lot of that with a higher inductance choke first, followed by slightly smaller (as long as higher also has higher resistance)
Looking good!
Loren
I was just figuring you were probably down more around 11-1200v. Even at 1200V, I would certainly trust these. Yes there is instant on spike, but look up data sheet, I bet even the 1.3kv ones could handle that. Also, you can get rid of a lot of that with a higher inductance choke first, followed by slightly smaller (as long as higher also has higher resistance)
Looking good!
Loren
The thing is that GM-70 has lower distortion at 1200V 80mA than 1100V 90mA, so, my main goal is to get the voltage higher than it is now, so choke input isn't an option. Choke input for driver stage would be nice though.
No problem, I'll look them up, you've been very helpful.
Keep up the good work.
No problem, I'll look them up, you've been very helpful.
Keep up the good work.
Oh, I didn't mean choke input. I meant higher value choke for the first choke in your cap input supply. Just helps with the initial pulse of HV the caps see. If you're using caps that are overrated, like those 2.6kv of yours, not a big deal. If you're using caps that are fine with the B+ (say 1.6kv) but don't want to see that much at the instance of startup, then it might be worth investigating.
Take care,
Loren
Take care,
Loren
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