TR-4

[Garey Barrell]

Don / Joe -

Most of these films are an ugly (to me at least) blue.  There is
someone who sells a kit of the white and blue filters, but it is a
yukky dark blue!

If you have a theater lighting supply house nearby, the Lee Lighting
No. 172 gel is a perfect color match to the original Drake filter
material.  It is a little thinner than the original, but the white
diffusion filter is thick enough so that everything stays in place.  A
24" x 20" sheet is less than $6.00.

Another supplier is Rosco lighting, their Roscolene #853 is supposed
to be the material that Drake used, but I have never seen it.  My
local supplier doesn't carry Rosco.  About the same price as the Lee
material.

The filtered light turns green with age for two reasons.  One is that
the original IS a blue-green shade.  The other is that the blue fades
to a lighter and lighter color, and the white filter tends to yellow
with age.  Blue + Yellow = Green.  A new white diffusion filter will
turn them blue again, just not VERY blue!  :-)

Still others have gone to blue colored LEDs.  Unfortunately the LEDs
that I have seen so far are too focused, resulting in a bright spot
near the center with rapidly fading intensity "off-axis".   The
"selling point" for the LEDs is that they have a 20,000 hour life
expectancy.  The 755 lamp rather than the original 47 is spec'd at
15,000 hours, and is a "drop-in" replacement.  I have been using 755's
in all my Drakes for over 10 years, and haven't had one die yet!

I guess I'm a Luddite when it comes to Drake's, I prefer to keep them
"as they were", warts and all!

73, Garey - K4OAH
Atlanta

----- Original Message -----
From: Don Buska

Joe,

A low cost method is to visit your local office supply store and check
out the index
card cover area.  They make these neat packs of multicolor milar film
covers that
slide over 4X6 index cards.  Doubled up, which is easy since these
covers are already
formed to cover both sides of the index card, it provides a very nice
blue for the
Drakes.  Or you can do what I did and choose a different color.  I use
yellow!  My 4C
line looks great with yellow filters and considering that for an
incandecent lamp they
naturally lean more toward the red end of the frequency spectrum.
That's why the blue
filters look green after awhile.  They are still blue just not blue
enough to filter
out the red end of the spectrum from the lamps filaments.

73

Don N9OO


On Mon, 23 Jun 2003 19:45:38 -0700, k7mks wrote:

>Am restoring a TR-4 and wish to replace the blue plastic filters for
the meters and
calibrated dial, both which are faded.  Any ideas for a source of this
material?
Finals need to be replaced - does anyone have 3 spares lying around
looking for a good
new home?  Please reply direct.  Many thanks, Joe k7mks

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