[AMRadio] Gas and mecury rectifiers


John coleman wa5bxo at gmail.com
Tue Apr 29 10:08:45 EDT 2008


Don, 
	I don't know why but this has stuck a curiosity point in me.

	Do you know anything about the pressure in these tubes?  I'm sure
the mercury vapor rectifier tubes are supposed to be vacated of air, but
what is the mercury vapor pressure and what is the difference in pressure
from cold to hot.  I wonder if it is just a result of a vacuum leak that
causes some type of corrosion on the anode. 
	Also I wonder what the gas pressure is in the 3B28 type gas
rectifiers and what the density of the gas is.  Maybe it is possible that in
the gas rectifiers the gas may actually seal or push the atmosphere away
from any leak.  
	In any case I bet that if mercury tubes where heated from day one
on, that they would have many more hours of good operation.  

Science fiction?
	Maybe the reason they need several days for heat up and then slow
anode voltage increase is to force air out that has accumulated over years
of setting cold.  This might not be possible in a vacuum rectifier but in a
mercury rectifier it might be that the mercury vapor pressure might displace
enough of the air forcing it back out 5the hole it came in enough to allow
it to work or perhaps the lengthy time is just causing a more homogenous mix
of the vapor and atmospheric gasses.
Science fiction?

John, WA5BXO





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