[Boatanchors] #44/47 Buld replacement with LEDs

Michael A. Bittner mmab at cox.net
Fri Feb 4 23:04:20 EST 2011

Thanks Gary, that clears up some questions. I'd always heard that damage could be done to an AA5 if a burned out pilot bulb were not replaced.

Next question: Should a 35W4 always have a pilot bulb connected, as in an AA5, for proper operation.  My Knight Ocean Hopper has a 35W4, but no pilot bulb.

Mike, W6MAB
  ----- Original Message ----- 
  From: Garey Barrell 
  To: boatanchors at puck.nether.net 
  Sent: Friday, February 04, 2011 7:38 PM
  Subject: Re: [Boatanchors] #44/47 Buld replacement with LEDs

  The 'tap' on the filament is NOT a 'center tap'.

  The problem with this system is that of course the bulb is subjected to 
  the initial surge of current when filaments are cold, causing that flash 
  that you see at turn-on.

  Worse still is that when the bulb inevitably burns out, the excess 
  current is forced through that portion of the filament in the rectifier, 
  causing it to fail open.  LOTS of rectifier tubes killed when the owner 
  noticed the bulb was out, but didn't want to take the radio to the shop 
  for repair!  Then he got to pay for a bulb AND a tube!  :-)

  73, Garey - K4OAH
  Glen Allen, VA

  Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
  and TR-4/C Service Supplement CDs

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