[TenTec] [Ten Tec} Centurion loading cap

[Hank P]

If you reduce the air gap even with “insulation” the breakdown voltage goes DOWN not up. Now sometimes , if the air gap is sufficient ,  the “insulation” will modify the field  of a sharp point or rough areas on a surface enough to keep it from breaking down – but it’s the field modification – not the “insulation” .


Don’t feel bad , others  had not thought about that either -  years ago – on a military project – an air variable we had was arcing , and the capacitor vendor said he had the solution , he  made us a special by putting  teflon coating on the rotor and stator plates – it broke down at a lower voltage than before !!!!! After the fact it was obvious – but we all suckered ourselves  in . 

But having said all that some Glyptal or about anything that will smooth that area – cover any sharp points and not decrease the air gap too much may just work. 

My recollection of that cap is it is made by  TT or someone for them  with spacers and plates all bolted together – you might be able to get a new plate/plates  – or if you tore it apart you might be able to get the area very smooth . If it is out near the edge you could just remove that area completely and smooth off the cut edge .

73 Hank K7HP