2979ee96   
   From: sfjssa@nospam.com   
      
   Patrick,   
      
   Words of wisdom, well said.   
      
   Would you have any idea why HP would use a 900 volt cap in this ckt?   
      
   Plate Voltage of the 6AU6 is 110vdc coupled by the .5 micro F to the grid of   
   6AQ5.   
      
   TIA   
   Vin   
      
      
   "Patrick Turner"  wrote in message   
   news:9cdc853c-6bdc-41ff-91c9-2081695fdac4@t11g2000yqk.googlegroups.com...   
      
   On Oct 2, 3:15 pm, "Trailboss"  wrote:   
   > Patrick,   
   >   
   > .5 F   
   > point five micro farad,   
   > the micro (using Alt 230 didn't come across for some reason)   
   >   
   > thanks Patrick,   
      
   If you use 0.47uF ployprop pot polyester, rated for 1,000V it should   
   be OK. If the oscillator F depends on the C being exactly 0.5uF, then   
   strap 0.027uF plus 0.0033uF across the 0.47uF to increase C to exactly   
   0.5uF. But any chosen 0.47uF may not be exactly 0.047uF, so the actual   
   value of additional parallel C to trim the value depends on the   
   calibration of your oscillator, and the C should be adjusted up OR   
   down until you get the correct frequency according to your frequency   
   meter and then the dial of the oscillator adjusted to suit the real   
   frequency, so that when you set the dial to say 100Hz, you get F =   
   100Hz +/- 3 Hz, and not oustide such tolerances.   
      
   Old oscillators are like old men, they get all wandery - blundery in   
   their thortatious processes, rather like young men, and only men of   
   middle age and at the height of their potential powers can muddle thru   
   with more accuracy than those yunger or older. Never stop thinking or   
   asking questions. Wives will hate you, but the wise will love ya.   
      
   Patrick Turner.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)