[Boatanchors] #44/47 Bulb replacement with LEDs

[Al Parker]

Hi folks,
	In the AA5 or 35W4 application, aren't we missing one of the purposes 
of the lamp?  It provides a load to balance out the voltage wanted 
across the tube filament.  An LED lamp is much lower a load, in the 
neighborhood of 10%, so it's not going to serve that purpose.
73,

Al, W8UT
www.boatanchors.org
www.hammarlund.info

"There is nothing -- absolutely nothing -- half so much
worth doing as simply messing about in boats"
Ratty, to Mole

On 2/5/2011 10:07 AM, Michael A. Bittner wrote:
> 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 <mailto:wcmoore at verizon.net>
>     *To:* infomet at embarqmail.com <mailto:infomet at embarqmail.com>
>     *Cc:* boatanchors at puck.nether.net <mailto: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:
>     http://www.r-type.org/pdfs/35w4.pdf
>      > 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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