From: trepidation@example.net   
      
   On 3 Sep 2025 14:20:27 GMT, Roger Hayter wrote:   
   > On 3 Sep 2025 at 15:03:52 BST, "Cursitor Doom"  wrote:   
   >> On 3 Sep 2025 13:56:25 GMT, Roger Hayter  wrote:   
   >>> On 3 Sep 2025 at 14:20:34 BST, "Cursitor Doom"    
   wrote:   
   >>>   
   >>>> I have an early AVO valve tester (twin panel type, Mk1 or Mk2) which   
   >>>> I'm trying to get fully working. Anyway, I have a problem with it   
   >>>> which I've never encountered before. I set the panels up to test a   
   >>>> valve, set the anode and heater voltages etc, the valves are glowing   
   >>>> just like they should, but when I apply the prods of a DVM across the   
   >>>> heater pins to check if they're correct WRT the switch setting, that   
   >>>> tiny extra load completely collapses the supply to the heaters! The   
   >>>> meter reads 0V (or close enough) and the heater glow dims to nothing.   
   >>>> Any idea WTF's going on here?   
   >>>   
   >>> Suppose you didn't actually use a bench DVM with one input connected   
   >>> to mains earth?   
   >>   
   >> I'm using purely battery-powered DVMs for this project. I don't even   
   >> have a bench DVM. Perhaps I'll try a scope instead and see how it   
   >> reacts to that.   
      
   Of course, the _last_ thing you would suspect is the DVM.....   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)