[ARC5] 7V and 14V Tubes

[Robert Eleazer]

Actually the Loctal Tubes with 7V and 14V filaments were indeed meant for 7V and 14V filament voltages.  They work OKay on 6V and 12V but were meant for the 14V and 28V voltages used in aircraft.  Of course, aircraft applications typically used the filaments powered right off the DC power buss while AC line operated radios used them either in a string or ran them off of a transformer. 

And I recall seeing a tube spec sheet that said the 7V filament tubes lasted longer that the 6V ones if used with 6V filaments.  So 7V tubes were an "improved" 6V as well as being more suitable for aircraft or vehicle use.    

Only recently I discovered there are some 5V filament tubes around, too,  and I have no idea why....

Wayne