[R-390] OT: Wet or Solid Tantalum?

[Barry]

The point may now be moot but he did send me the markings:

+H/E HNW 
47 + - 10% 
+50VDC 
7911 

After re-reading National's application notes for the LM117/317, it states that 1uF is all that's really needed on the output.  Not sure why their "typical designs" show more than that (apparently it's application dependent), but I think I'm going with 1uF.  If I have problems with it, I can always exchange the value later.

The application "hints" go on to say that for better ripple rejection, a 10uF is recommended on the ADJustment line and I plan to use that, but the output's only getting a 1uF cap.

Thanks again, guys.  I guess I need to return the list to its regularly-scheduled R390[A] program.

Barry - N4BUQ
  ----- Original Message ----- 
  From: eldim at att.net 
  To: rbethman ; n4buq at knology.net 
  Cc: r-390 at mailman.qth.net 
  Sent: Monday, November 10, 2008 4:06 PM
  Subject: Re: [R-390] OT: Wet or Solid Tantalum?


  The one pictured on the ebay  acution in the UK is a U.S.A. Manufacted Tantalum (sintered wet slug), but only very mildly wet if memory serves me correctly.  If they have a silver casing, and I do mean real (silver), then the solid tantalum slug inside is machined smooth and is connected to solid tantalum wire that exits thru a Teflon bushing.  This is a wet type that has a Potassium-Hydroxide (alkaline) solution to form the electrolyte.  This last type of Tantalum is known for it very high accuracy, stability and does not change with altitude, and temperature.  I have a brochure from one of the major areospace from years ago buried somewhere in my library which is blocked at this time. Tantalum come in rod form, solid wire, and foil.
  The prettist is the two different colored foil sheets that is spooled in the TANTA-LEX electrolytics manufactured by GE which is encased in an aluminum cased with axial welded leads.  The two Tantalum foil types are seperated by a wet impregnated paper (that stinks), but is required to form the dielectric.

  Hope that this info helps and is correct as my memory is slipping.
  73,
  Glen Galati, KA7BOJ
  Tacoma, Wa.
  eldim at att.net
  253-272-1061
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