Steven Swift wrote:
"Lynn Coffelt" writes:

I believe that 50C continuous operation means that is the maximum
temperature for continuous operation. Ambient air temperature (and even
altitude in airborn stuff) as well as circulating air make a world of
difference. Smoking the shellac is not good, and can be smelled easily if
you remove the end dust caps, and leave them off. In the golden days, I
thought something was wrong with dynamotors on surplus so-called Command
Sets if I couldn't leave the palm of my hand on the dynamotor for 10
seconds. Ouch, ouch, ouch........
Old Chief Lynn

I found an old manual in my stash that talks about "FITCAL" for
checking out old radios. This TM-11 manual said that the dynamotor is
okay if you could "lay your palm on it for 5 seconds without
discomfort."

Reading that as a spec, my dynamotor is running just fine. There's
no smell of burning.

The radio room in a B-17 must have been buzzing with dynamotors...

I think screaming is more the word. I remember walking alongside of
a B1 at an air show when someone fired up the Auxiliary Power Unit (APU).
Now that was loud. The airplane folks never seem to worry much about
how noisy their planes were inside. They just wore ear protectors.

-Chuck