What are these Capacitors?

[rider]

Hi !
I need to reverse an existing board which is delta-modulator for speech application. The existing board has some big plastic box capacitors(orange color) and non-standard capacitances. They are from Siemens but i can't figure out whats their type (i guess they are Polystyrene (Styroflex?) ) or may be polycarbonate?. I think they are obsolete now? If not where these could be available? If not what could be the replacement?
Please see the attached pic. They are labled as KS 63V, capacitance value with a tolerance letter F, H or J, so they are of very high accuracy.
Please help.

Rider

 

[Sch3mat1c]

Those are usually for across the power line to filter HF hash from power supplies to keep it from going back up the power line, causing interference. Though obviously not this one, 63V won't cut it exactly. AFAIK, they are mylar (polyester). 6800 = picofarads (pF) = 6.8nF = .0068uF.

Tim

 

[roddyama]

If the guy with this ad on eBay is on the level, those are teflon caps. They look the same.

 

[rider]

But what about KS?

Hi!

Thanks for your replies. But please also note that there is a label "KS" on the cap, which is usually code for Polystyrene film/foil. So how can these be Mylar or Teflon?

Thanks

 

[peranders]

I vote also for polystyrene. I think some persons think that it's teflon... or want it to be that.... or just say it in order to get more money for those caps.

 

[Sch3mat1c]

Re: But what about KS?

Thanks for your replies. But please also note that there is a label "KS" on the cap, which is usually code for Polystyrene film/foil. So how can these be Mylar or Teflon?

Because they look like it. Hell, I don't care what a cap is, as long as it does it's job.

Tim

 

[moamps]

http://www1.jaycar.com.au/images_uploaded/rescode.pdf

or

http://www.electronics2000.co.uk/data/itemsaf/capmarks.htm

or

......

Regards
Milan

 

[rider]

Price issue

Hi!

Thanks to all of you for replies. I think "Peranders" made a good point about price. Since Teflon caps are very expensive, so some guys, (like the one on ebay) rate their price too high by misleading about the type. Polystyrene caps are also considered suitable for filtering/audio applications and so as teflon.

About the usage, I have these caps in an Aerospace application card (a delta modulator for speech ), so I guess these must be critical in that place. Also the values i have are odd like 8.25n, and 7n etc with tolerances of 1%-5%. So I feel they DO matter .

Regards
Rider

 

[jacco vermeulen]

Just for completeness, as i tripped over this thread by chance, earlier production type was the B31521=>

 

[jacco vermeulen]

And not exactly cheap, wholesale price in DM, ex VAT (1988)=>

 

[jacco vermeulen]

On the other hand