[ARC5] RE: [MRCA] BC-348 Dynamotor Temp.

[Lenox Carruth]

After one hour of operation at 75 F ambient mine measures 125 F with my
infrared thermometer.  The stated temperature rise on the dynamotor label is
40 C which is 104 F.  That would appear to mean that, at an ambient
temperature of 100 F, the dynamotor could run at 207 F and not exceed its
rated temperature.  This is, of course, too hot for your hand so I don't
think the hand test is necessarily valid.

FYI, I never run a dynamotor without first disassembling it, cleaning the
bearings, and relubricating them with an appropriate, modern lubricant.  I
have never found this to be a difficult operation.  You can remove the end
bells, hold the dynamotor, one end down, over a tray of solvent and use a
small brush to clean the bearings.  Don't let the solvent get on the
brushes, wiring, commutator, etc.  Lubricating is easily done with a flat
toothpick which will allow you to get the lubricant down between the balls.
Just be sure you don't use too much lubricant and don't get it on the
commutator or brushes.  Do the same to the other end and you've got it.

P.S.  I have never found a WW-II era dynamotor where the original grease was
still good so don't run them without fresh lubrication.

Lenox



-----Original Message-----
From: mrca-bounces at mailman.qth.net [mailto:mrca-bounces at mailman.qth.net]On
Behalf Of W7QHO at aol.com
Sent: Tuesday, April 15, 2008 2:38 PM
To: milsurplus at mailman.qth.net; arc5 at mailman.qth.net; mrca at mailman.qth.net
Subject: [MRCA] BC-348 Dynamotor Temp.


All,

Have worked on several 348s over the years but this is the first one with an
original dyno (DM-28-R).
How hot do these things get when operating at rated in/out voltage and
current?

Thanks.

Dennis D. W7QHO
Glendale, CA




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