cap values
¿ªÔÆÌåÓýits a 220pf 500v silver mica according to the circuit diagram its probably a 220pf ceramic in 0805 size from what I observe of
an unbuilt PCB - hth On 21/03/2023 01:33, Paul M3VUV wrote:
ive burned a cap in my atu,see pic,can anyone recomend what i need to replace it with ,ie value and type?,cheers +73 |
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Surface mount silver mica capacitors exist. You have to step up to the larger 1210 size rather than 0805 to get parts that are rated for 500V; the 0805 ones are only rated for 100V. You're unlikely to encounter silver mica capacitors in ATU100 kits or assembled tuners from China because they are expensive; For example, here is a suitable part from Digi-Key in the 1210 size:?? Those cost $4.23 in quantity one, coming down to $2.65 if you buy 100 or $1.74 if you buy 5,000, but you can't currently buy 5,000 because they don't have that many in stock. The smaller values are a bit less expensive, and prices in China are likely to be lower than US distributor prices, but nonetheless it would be prohibitively costly for the kit seller in China to provide seven of those capacitors in a kit that sells for about $30 delivered. NP0 ceramic capacitors are much less expensive, and they're available in an 0805 package. For comparison, here is the least expensive 500V NP0 capacitor in the 0805 package on Digi-Key:?? That one costs 18 cents in quantity one, 6 cents in quantity 100, or 3 cents each on a reel of 4,000. Those are the kind of parts you're going to find in a kit from China, not the expensive silver mica version. Other brands are more expensive; the next cheapest one that's in stock right now costs 48 cents in quantity one, which is still far cheaper than the silver mica. Will the less expensive ceramic capacitor work? If they have provided high quality ceramic caps, yes. Will losses be as low as the silver mica? Unknown; testing is in order. On Tue, Mar 21, 2023 at 6:19?AM mike <pencoys@...> wrote:
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If I can put together a $100 CAD order, I get free shipping. Mike, do you know what the threshold for free shipping is in the US? I have a mailing address in the Ohio I can use...
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tia de va3rr On Wed, Mar 22, 2023 at 09:49 AM, N2MS wrote:
Mouser and Digikey have minimum fixed shipping. I make a list of parts and |
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I've also dealt with LCSC for components when I ran a group purchase for partially assembled (tr)u-SDX boards, and DL2MAN bases his BOM mostly on LCSC part numbers. I recall the shipping being relatively cheap and they do seem to have a pretty good selection of parts, as long as you exercise due diligence.
Just throwing it out there as a possible alternative... 73 de Russ, va3rr |
mike
Shirley Dulcey KE1L
va3rr