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.003mf caps on Philco 40-195 - Printable Version

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.003mf caps on Philco 40-195 - dgarvin57 - 06-18-2016

I am restoring a 1940 Philco model 40-195 and I'm having trouble sourcing the two .003mf 1000 V capacitors connecting from the plate of the two output tubes (42) to ground. I have one .003mf 630 V capacitor that I sourced from a company in Canada (I miscounted when I ordered and so only ordered one when I should have ordered two). I'm not sure whether the 630V rating is enough. Also, due to a dispute in a past order, the Canadian company invited me not to order from them again.

I then ordered what I thought were .003mf 1500V caps from an outfit in Bulgaria on eBay. When I received them and tested them, they showed .012 mf instead, not the .003mf I expected. They are labeled "3n0 K MKPI 1".

1. Can I use the one .003mf 630V capacitor that I have?
2. Is it safe to use the .012mf capacitors that are supposed to be .003mf?
3. If I need to purchase the right capacitor, can you recommend a source? (I've checked mouser.com, digikey.com and others.)
4. If all else fails, is there a way to make the required .003mf capacitor by combining other caps?

I'll attach some pictures. Thanks in advance for your help.

RE: .003mf caps on Philco 40-195 - Radioroslyn - 06-18-2016

Hi and welcome,
The simple answer is use two .006mfd@630v in series. =.003@1260V

tERRY

RE: .003mf caps on Philco 40-195 - dgarvin57 - 06-20-2016

Really appreciate your response. Good idea about putting them in series. Unfortunately, I'm still having a hard time sourcing a .003 or .006 film capacitors at 1000 V DC. If I didn't want to use vintage looking caps it would be okay to use ceramic disc capacitors, right? They are much easier to come by. thanks again.

RE: .003mf caps on Philco 40-195 - Radioroslyn - 06-21-2016

You can use 2 .0068 or .0075's. Values isn't super critical, it's used to quench the high frequency response  which helps keep the audio output stage from oscillating. Have seen caps as large as .02mfd in some circuits. With that large of a cap it tends to make the audio sound muffled. Another reason why a larger value is that it gives the appearance that the set has more selectivity by eliminating the audio portion adjacent station splatter. Sometimes I'll adjust the value a little to .01 or .005 it really brightens up the sound and sounds louder. Disc caps are fine too. If you are into restuffing the mylars are easier to work with, you probably fit the two into the old cap casing.
That's the longer answer.
GL

Terry

RE: .003mf caps on Philco 40-195 - Nick3092 - 06-21-2016

Mouser has some Panasonic .003@1600v radial film caps that would do the trick too. Just watch the part numbers. Some are short crimped style leads. The data sheet will tell you what to look for in the part number to get "normal" leads.

RE: .003mf caps on Philco 40-195 - dgarvin57 - 06-24-2016

Thanks all for the great info and advice. Terry, good to know about the alternatives and the impact. Nick3092, I was able to find a .003 1KV film cap with straight legs on Mouser. Thanks again.