Voltage Ratings (Boltage Ratings) In KK Teflons

[Grainger49]

I know how much Doc and Paul dislike the topic of capacitors.  But... this isn't about "your favorite..." or "which to use..." it is the voltage ratings.

It is no secret that I am a fan of the USSR Military Surplus Teflon capacitors that some of us call KK Teflons.  

The KK Teflons are not rated in the same voltage breaks as most of the capacitors we use.  (The ratings use "B" instead of "V" and that is the reason for the title.)  The breaks seem to be 200V, 500V, 600V and 1000V.  American & European capacitors are rated at different breaks in values.  

Now the question: in current Bottlehead equipment can a 600V KK Teflon be used as a coupling capacitor where Doc and PJ have used 630V ratings?

A little while back Paul said not to use the 200V rated capacitors that were advertised as "tested at 1000V."  I agree, that is why they have the three ratings higher than 200V.  Only the designers of the equipment know if the 30V in "rated VDC" makes a difference.

 

[Paul Joppa]

Some other caps - Auricaps maybe? - carry 600v ratings and we have not seen problems with them. As you know, I'd rather see higher ratings for parafeed caps because of the inductive load which could allow a voltage higher than the power supply to appear across the caps.

Obviously I can't guarantee that the KK ratings will work the same as Sprague or Panasonic.

Teflon and foil is always a problematic construction because teflon is actually a liquid, like glass but softer. So it is always a risk that a short will form. I believe the usual solution is to make the teflon much thicker than necessary and hope for the best, hence the huge size and the huge initial voltage test. I have never found any authoritative source for this, however - it remains speculation.

Incidentally, the second letter of the alphabet, in Greek as well as Russian, is pronounced with a v-sound - if you pronounce b and v, you will see that the mouth formation is nearly identical. That's probably why they are adjacent on a typewriter keyboard as well.  :^)

 

[Grainger49]

Paul, thanks.  I didn't remember that it was only the Parafeed caps you like to have higher ratings.  That is the answer I am looking for.  I have had a 500V KK Teflon as my interstage cap in my Paramours for several years (a Bottlehead community group buy).  

And I didn't know about the pronunciation.  I should have asked my brother, he speaks Russian.

So in the Paramount, Eros, Seduction, Foreplay III, SEX and upcoming Stereomour where a 630V capacitor is used for coupling, but not Parafeed, the lower 30V shouldn't give trouble as long as the Teflon doesn't thin out.