[Boatanchors] #44/47 Bulb replacement with LEDs
anchor at ec.rr.com
Sat Feb 5 10:34:17 EST 2011
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.
"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:
> > 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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