[Boatanchors] 100TH and 250TH advice and or comment

[rbethman]

Question:

I have noticed that the 100THs and 250THS that are in their original 
boxes, either not used at all, or maybe use for less than an hour to 
test them, seem to be doing fine.

Their envelopes are crystal clear an can not see any sort of defect.

Then the ones that are in one of the two BC-610s that has the hours on 
it, even though it last performed flawlessly, now appears to have gone 
gassy with some milky white inside the envelope.

Is this perhaps due to over heating or maybe I should phrase this as the 
convection cooling of these radios since they do NOT have fans.

Ideas?  Comments?

It has always been metered and watched with a scope for observing 
waveforms, and the wattmeter is the newer Model Bird with peak reading 
built-in.  (However true they really are!)

Bob - N0DGN