[Boatanchors] #44/47 Buld replacement with LEDs

Michael A. Bittner mmab at cox.net
Sat Feb 5 10:07:41 EST 2011

Chuck, Thanks for the info and data sheet on the 35W4.  Looks like it's OK to use the 35W4 in a series string without harm as in my Knight Ocean Hopper and according to the alternate diagram on the data sheet.

This still leaves us with the question of how one of these #47 bulb LED substitutes would work in an AA5 radio.  After all, the D in LED stands for diode.  W6MAB
  ----- Original Message ----- 
  From: Chuck 
  To: infomet at embarqmail.com 
  Cc: boatanchors at puck.nether.net 
  Sent: Friday, February 04, 2011 9:45 PM
  Subject: [Boatanchors] #44/47 Buld replacement with LEDs

  The 35W4 is a bit of a strange bird. The filament is tapped but rather than
  being tapped at the center like the venerable 12AU7 and similar valves the
  35W4 is offset so that there are different drops across each filament section.

  From Pin 3-4 with a #47 Lamp the filament drop is 32 Volts. From Pin 4 - 6
  the nominal drop is 5.5 volts.

  For more info see the datasheet at the follwoing URL:


  > Great question......thanks, Mike!
  > 73....Walter - K5EST - Missouri
  > On Thu, Feb 3, 2011 at 7:39 PM, Michael A. Bittner wrote:
  >> How would these work in an AA5 radio where the #47 bulb is often 
  >> connected
  >> across one half of the rectifier heater? Rectifiers are typically 35Z5 or
  >> 35W4 with center-tapped heater. Mike W6MAB
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