[R-390] Dail Lamps Again A Little Help Needed (long)

Tue Aug 7 19:37:47 EDT 2007

Guys:

The dial lamp issue has been discussed at length. It
may be found under "Restoration_general" in the
"Pearls".

Roy's post today says it all re exact replacements.

Here are snippets re LED's from "Pearls":
---------------------------------------------------------------
>Date: Mon, 13 Aug 2001 19:52:32 -0500
From: "Richard Biddle" <theprof at texoma.net>
Subject: [R-390] White LED 328 dial lamps

I came across an article in Electronic Design on LED
lighting.  I went to one of the sources, LEDTronics
(http://www.ledtronics.com/ and they had LED
replacements for the #328 lamp.  Colors range from red
to white to blue.

>From the catalog:  T1æ (5mm) Midget Flange-Based LED's

Part Number: F200-0CW-005B
Color: 8000K Cool White SiC/GaN
Retail Price: $9.50
Illumination Angle: 120
Voltage (V): 5/6 V (B)
Typ Current (mA): 160
Typ Intensity (mcd): 15

B = BiPolar AC/DC

Haven't bought any as yet, but I thought it looked
neat.
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>From: "Jerry Kincade" <w5kp at direcway.com>
Subject: Re: [R-390] Dial Lamps
Date: Fri, 3 Jan 2003 10:52:13 -0600

Amen, Barry - I'd also love to have some specifics
from somebody who has adapted the display illumination
to use either green (or even better orange)
diffused-lens LED's. I'll bet a coat of flat white
paint on the inside of the dial cover would reflect a
nice, even-colored glow on those white dial numbers,
and they would show up great on their flat black
background. How cool would that be? For the coup de
grace, add a tiny little pot (inside, of course) to
control the LED brightness!  :-)
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>Date: Fri, 03 Jan 2003 12:14:03 -0500
From: Bob Camp <ham at cq.nu>
Subject: Re: [R-390] Dial Lamps

The LED's work and they aren't all that expensive
these days. Digikey has some *very* bright ones for a
couple of bucks each. Compared to say a R-1051 there's
a lot of room in a R-390A to mount a couple of them
and a dropping resistor.
The main issue is the same one we keep chasing all
over the place here. They are DC parts so you have the
possibility of RFI when you put them in. Running two
back to back still gives you a non linear load.
Anything non-linear and you get crud.
-------------------------------------------------------------
>Date: Fri, 03 Jan 2003 14:43:37 -0500
From: Bob Camp <ham at cq.nu>
Subject: Re: [R-390] Dial Lamps

There was a thread a while back about taking a dead
light apart. You then installed a dropping resistor
and a small LED in the base. The net result was a half
wave rectifier and a test for the reverse breakdown of
the LED being > 10 volts. The main problem mentioned
was that the LED used was a narrow beam type and it
didn't light up the window as well as a pilot light.
---------------------------------------------------------------------------------------------------------
>From: ToddRoberts2001 at aol.com
Date: Fri, 3 Jan 2003 16:34:19 EST
Subject: Re: [R-390] Dial Lamps

Mendelson Electronics have several interesting T 1-3/4
lamp based high-intensity multi-chip LED's @ 40 cents
each. They are rated 6VDC @ 35ma and come in RED,
AMBER or GREEN colors. They come already mounted in a
T 1-3/4 midget flange base for drop-in replacement.
Don't know if they would operate from 6.3VAC but would
be fun to experiment with!  Go to www.meci.com and
click on their LED Listings. 
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>Date: Tue, 6 Jul 2004 22:26:47 -0700 (PDT)-
From: John Kolb <jlkolb at cts.com>
Subject: Re: [R-390] Re: LED lamp replacement

While there may be a possibility of RFI generated by
the LED's or (blasphemy) solid state diodes, I'm more
curious about the light output. The light out of LED's
is rather directional - how well do they work in the
R-390?
-------------------------------------------------------------------------------------------------------
>Date: Wed, 7 Jul 2004 04:17:26 -0400
From: "JamesMiller" <jmiller1706 at cfl.rr.com>
Subject: Re: [R-390] Re: LED lamp replacement

I prefer the "soft" on and off times of filament lamps
over the instantaneous on-off of LEDs.  My filament
dial lamps sort of "ramp up" when they come on, which
is the true behavior that should be observed in this
genre of radi?  .  Ever drive behind a car with those
obnoxious LED brake lights, especially the Cadillacs?,
They flash on instantly... no soft warm up time.  It's
grating on the nerves.
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>Date: Wed, 07 Jul 2004 17:02:34 +0200
From: "Bryce Ringwood" <BRingwoo at csir.co.za>
Subject: Re: [R-390] Re: LED lamp replacement

The LEDs I have cast an eerie bright whiter than white
light - very unpleasant. I guess you could use a
ballast tube to soften the start up time*. Have any of
you had RFI from a filament light ? Some sort of weird
RF can be generated between the filament and metallic
deposits on the glass envelope in old lamps. So I'm
told. 
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>Date: Wed, 07 Jul 2004 11:24:09 -0400
From: Roy Morgan <roy.morgan at nist.gov>
Subject: Re: [R-390] Re: LED lamp replacement

That's the little known process of a monode turning
into a diode. It does it all by itself.  No physicists
needed.
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>Date: Wed, 7 Jul 2004 10:40:06 -0500
From: "Cecil Acuff" <chacuff at cableone.net>
Subject: Re: [R-390] Re: LED lamp replacement

Put a big electrolytic in parallel with them...that
should do it!
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So that all came forth from this group in the distant
past of 2000-2004

Thanks

W. Li
Mercer Island, WA

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