From: liz@poppyrecords.invalid.invalid   
      
   Cursitor Doom  wrote:   
      
   > On Sun, 12 Oct 2025 18:38:50 -0000 (UTC), Jerry Peters   
   >  wrote:   
   >   
   > >Cursitor Doom  wrote:   
   > >> Hi all,   
   > >>   
   > >> I've got this old Grundig radio made in 1972 and the main tuning cap   
   > >> gets scratchy from time to time owing to a design defect where they've   
   > >> put the moving contact at 90 degrees to the shaft so it runs in a   
   > >> narrow slot, rather than the more common leaf spring contact. Over   
   > >> time, this has worn and as it has, it doesn't self-correct for tension   
   > >> like the leaf type does. So I've been using a switch cleaning   
   > >> lubricant on it, which works great for about 6 weeks, but then it's   
   > >> getting scratchy again. Is there something more permanent I can use to   
   > >> maintain good contact? I'm thinking maybe copper grease like the stuff   
   > >> they use on brake pads to stop squealing. Would that work? Switch   
   > >> lubricant fluid is just not sludgy enough to stick around!   
   > >>   
   > >> CD.   
   > >   
   > >Powdered graphite used for locks perhaps?   
   >   
   > Powder? Not so much. But they do make a graphite grease and I plan to   
   > try that if the other ideas fail.   
      
   With conductive particles in a non-conductive medium, the proportion of   
   conductive material is quite critical.  Conduction only begins to occur   
   when there are enough particles to touch each other, so you will need to   
   check your graphite grese for conductivity with a couple of ohm-meter   
   prods.  You might be better off adding just enough grease to graphite   
   powder to make it stick and not blow about.   
      
   (This explains why most zinc-based primers are useless, because the zinc   
   particles aren't touching and cannot contribute any electrolytic   
   action.)   
      
      
   --   
   ~ Liz Tuddenham ~   
   (Remove the ".invalid"s and add ".co.uk" to reply)   
   www.poppyrecords.co.uk   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)