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

[Neil]

----- Original Message ----- 
From: "Lenox Carruth" <radios at sbcglobal.net>
To: "Military Radio Collectors Association" <mrca at mailman.qth.net>; <milsurplus at mailman.qth.net>; <arc5 at mailman.qth.net>
Sent: Friday, April 18, 2008 10:49 AM
Subject: [ARC5] RE: [MRCA] BC-348 Dynamotor Temp.


> 
> 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.


I think 207 F is a typo, and you meant 204 F.  Having said that, there appears
to be an error in your methodology. It's incorrect to convert 40 C to F, because
it's a temperature *rise*, not an absolute temperature.

The correct process is to convert your ambient 100 F to C, add the 40 C rise,
then convert back to F.

100 F =  37.8 C.  Now add 40 C  (77.8 C).  Now convert back to F  (172.0 F).

So at 100 F ambient, calculation shows the dynamotor should run at 172 F.

Using the same method for your infrared thermometer measurement of 125 F,
your dynamotor seems to be running within its rating (calculation gives 147 F).

73 de Neil ZL1ANM