Re: 4-125a amp for fusor ion trap
Posted: Sun Feb 24, 2019 5:45 pm
I don't need exact value here, it's more or less a low ESR/L bypass. But I can't seem to find doorknob caps with anything like those values. All the HV ones are in the hundred pf range...and all the big capacities are in the couple kv range (surplus sales etc). As far as searches here in the US go, so far.
Do you know if those glassmike plastic caps are any good? We did find one for "only" $139 + ship.
We might have up to an amp RF there (optimistically, it's probably going to be a lot less). I'm just trying to keep the Spellman safe here and not waste too much power in heating capacitors. A little reactance will tune out just dandy if it isn't lossy. In this scheme, at least for now, we just get "close" in frequency and tune the rest (like they did with cyclotrons and for the same reasons - everything else is easier to tune).
This place is one of our better sources in the USA: https://www.surplussales.com/home.html#Capacitors
Amazon is showing some ceramic disk caps with the right ratings(!) but I'm betting it's those lazy chinese leaving out a decimal point in the kv rating, as they're too small to not just arc between the terminals at 50k..https://www.amazon.com/50000V-2200PF-Vo ... B075SRXR5J
Unless those are really 5" in diameter or more and that lead wire is #8 or bigger...kinda doubt it.
I'll keep you in mind about those NOS tubes. These seem new so far - the crumbling brown paper they were labeled with said so! (and they measure good and reasonably matched). I'm trying to take as much of Bob's advice as I can and keep from frying them (or anything else).
Don't you love it when you see new printed on something decades old?
Do you know if those glassmike plastic caps are any good? We did find one for "only" $139 + ship.
We might have up to an amp RF there (optimistically, it's probably going to be a lot less). I'm just trying to keep the Spellman safe here and not waste too much power in heating capacitors. A little reactance will tune out just dandy if it isn't lossy. In this scheme, at least for now, we just get "close" in frequency and tune the rest (like they did with cyclotrons and for the same reasons - everything else is easier to tune).
This place is one of our better sources in the USA: https://www.surplussales.com/home.html#Capacitors
Amazon is showing some ceramic disk caps with the right ratings(!) but I'm betting it's those lazy chinese leaving out a decimal point in the kv rating, as they're too small to not just arc between the terminals at 50k..https://www.amazon.com/50000V-2200PF-Vo ... B075SRXR5J
Unless those are really 5" in diameter or more and that lead wire is #8 or bigger...kinda doubt it.
I'll keep you in mind about those NOS tubes. These seem new so far - the crumbling brown paper they were labeled with said so! (and they measure good and reasonably matched). I'm trying to take as much of Bob's advice as I can and keep from frying them (or anything else).
Don't you love it when you see new printed on something decades old?