[Boatanchors] #44/47 Buld replacement with LEDs

Garey Barrell k4oah at mindspring.com
Fri Feb 4 22:38:57 EST 2011

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

Wilson Lamb wrote:
> Aren't these 6V lamps?  How could you connect one across 17.5V of 
> filament??
> Wilson
> ----- Original Message ----- From: "Walter - K5EST" 
> <walter.k5est at gmail.com>
> To: "BoatAnchors" <boatanchors at puck.nether.net>
> Sent: Friday, February 04, 2011 8:19 PM
> Subject: Re: [Boatanchors] #44/47 Buld replacement with LEDs
>> Great question......thanks, Mike!
>> 73....Walter - K5EST - Missouri
>> On Thu, Feb 3, 2011 at 7:39 PM, Michael A. Bittner <mmab at cox.net> 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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