[R-390] Re: Refinishing meters

[Scott, Barry (Clyde B)]

Roy,

Good [repeat] advice.  One of the meters (Carrier Level) is marked "Sealed -
Do Not Open" while the other (Line Level) is not marked as such.  I wonder
if the Line Level meter would be considered "safe"?  I haven't opened either
of them, partly because of the radiation thing.  I have noticed that the
Line Level meter doesn't appear to be all that well sealed (see pictures) so
I'm thinking it may not be a threat.

What think ye?

73,

Barry(III) - N4BUQ

-----Original Message-----
From: Roy Morgan [mailto:roy.morgan@nist.gov]
Sent: Wednesday, April 30, 2003 1:13 PM
To: R-390@mailman.qth.net
Subject: Re: [R-390] Re: Refinishing meters


At 07:01 PM 4/29/03 -0700, Ron wrote:
>David-
>make yourself a wrench ... movement can be removed after removing the nuts
>on the back holding solder lugs.

Would-be Meter Disassembles,

I have the urge to repeat Morgan's Law of Radioactive Meters and Regulator 
Tubes: tu wit:

DON'T BREAK THEM OPEN AND EAT THE INSIDES.

To elaborate slightly:

1) SOME meters from R-390's and other radios have glow-in-the-dark meters 
containing alpha-emitting radioactive sources.  (EVen though it does not 
glow anymore, the stuff is still in there.)

2) Many military OA2 and similar regulator tubes have small amounts of 
radioactive material in them to ensure reliable ignition especially in the 
dark and cold.

In both cases (pun intended!) the stuff is pretty harmless unless you get 
the case open and get the material on you or inside you (by breathing or 
ingestion or through a cut or abrasion).  Make sure this does not happen!

What does "pretty harmless" mean? I remember one analysis that concluded 
something like: You would have to place an R-390A meter on your chest or 
cheek for about 34 years before you'd be exposed to radiation equivalent to 
the minimum yearly radiation exposure.  However, ingestion or inhaling the 
dust from a meter's markings or tube innards places the material in direct 
contact with your tissues and could lead eventually to cancer or the 
like.  A sealed meter or unbroken regulator tube envelope effectively 
contains all alpha emissions.

The bottom line:

If you are going to take R-390 meters apart:
Make VERY sure you know what kind of meter you have and what you are doing.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Work: Voice: 301-975-3254,  Fax: 301-948-6213
roy.morgan@nist.gov --

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