Famous: If you need small cap values, consider a film cap, as they will outperform electrolytics in every way. They don't have life/temp issues like electrolytics, and are available in 630V ratings. A Solen 22uf 630V cap is about $11. They get physically large in a hurry though in larger values.
As far as busting the specs for first cap on a 5U4, many folks do it with no problems, but studying the data sheet for minimum transformer impedance and first cap values is a good idea.
One other thing that may be useful for dialing in your final B+ voltages; if you are using a CLC topology, reducing the value of the first cap will reduce the B+ once you get below about 8uf or so. Play with this in your PSUD model. Reduce the value of the first cap down to a couple of uf, or even less than 1uf.
As far as busting the specs for first cap on a 5U4, many folks do it with no problems, but studying the data sheet for minimum transformer impedance and first cap values is a good idea.
One other thing that may be useful for dialing in your final B+ voltages; if you are using a CLC topology, reducing the value of the first cap will reduce the B+ once you get below about 8uf or so. Play with this in your PSUD model. Reduce the value of the first cap down to a couple of uf, or even less than 1uf.
Hi,
If you only need small value (under 100uF), you can go with Solen/SCR. They have rating up to 630V while the capacitance around 22-47 is easy to find. Mostly you cant go wrong with film caps, although YMMV.
I also love the Jensen 4pole, Mundorf MLytic, Unlytic, ASC, and off course Black Gate WKZ. All are very good. Used depends of your taste, could be combined.
Except Unlytic, I think most of the has 'reasonable' size...
Below is comparison between Unlytic 290uF/750VDC with some stuff (RCA 5U4GB, and other smaller stuffs).
If you only need small value (under 100uF), you can go with Solen/SCR. They have rating up to 630V while the capacitance around 22-47 is easy to find. Mostly you cant go wrong with film caps, although YMMV.
I also love the Jensen 4pole, Mundorf MLytic, Unlytic, ASC, and off course Black Gate WKZ. All are very good. Used depends of your taste, could be combined.
Except Unlytic, I think most of the has 'reasonable' size...
Below is comparison between Unlytic 290uF/750VDC with some stuff (RCA 5U4GB, and other smaller stuffs).
I think for my first build I am going to go on the less expensive side just in case I make a mistake. Also I think it is a good learning experience to build something and listen to it for a while, then upgrade say the power supply or coupling caps and then I can really A/B what upgraded parts can do from a sonic point of view.
Good plan. You can use any cap as long as the voltage rating is sufficient. You can also wire them in series to double the voltage rating (see Mile's post above) at the expense of 1/2 the uf value; you need 100Kohm or so balancing resistors across each cap to assure that they share the voltage equally (simple voltage divider).
You can also bypass (wire in parallel) electrolytic caps with film caps to improve ESR. A 100:1 ratio is typical, so bypass a 22uf electro cap with a .22uf film cap for added goodness.....The 100:1 ratio is a guideline, so keep that in mind when reaching into the parts bin.
If this is your first build don't get hung up on boutique parts, just procure some good quality/affordable caps like Panasonic, Cornell Dublier, etc, etc.
Another 500V cap alternative that just came to mind are the JJ cans. They are available as single caps per can and multiple caps per can. Check out this link:
Can Capacitors
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Hi,
If you only need small value (under 100uF), you can go with Solen/SCR. They have rating up to 630V while the capacitance around 22-47 is easy to find. Mostly you cant go wrong with film caps, although YMMV.
I also love the Jensen 4pole, Mundorf MLytic, Unlytic, ASC, and off course Black Gate WKZ. All are very good. Used depends of your taste, could be combined.
Except Unlytic, I think most of the has 'reasonable' size...
Below is comparison between Unlytic 290uF/750VDC with some stuff (RCA 5U4GB, and other smaller stuffs).
hi, can you tell how much those big caps cost? are those available in your place or do you order them online? can you post your source here? thanks...
The PTX for that project was a NIB Stancor. I got it cleaning out an attic where an old time ham used to live. He had a bunch of stuff like that, probably left over from a project that never got built.
Hmm...then I may want to get another pair of caps, I think the secondary is about 435v, or is it 320 then 435 after rectification....I better have another look 
Edit: OK, the transformer is from a Yaqin MC-10L, so secondaries are 320v & 40v....the 320v is then rectified into 435v?
So what one am I looking at being 1.4x of?
I would have thought the 435v after rectification...
Edit: OK, the transformer is from a Yaqin MC-10L, so secondaries are 320v & 40v....the 320v is then rectified into 435v?
So what one am I looking at being 1.4x of?
I would have thought the 435v after rectification...
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