Post by thread:[EE] Migration (was Wire wrapping insight needed!

"Paul James E." writes: > Negative on the DC for the filaments. Modern (60's to now) tubes have > heaters that are designed for AC. If you use DC, there is a chance of > premature failure of the heater because of migration. What is migration in this context? One would think that pure DC would be ideal for powering tube filaments and incandescent light bulbs because it does not generate mechanical vibrations in a fragile filament due to electromagnetic fields. Also, the temperature will stay rock steady as soon as it reaches maximum heat since there is no AC component to cause a slight but continuous temperature cycling every half-cycle. I remember an article in "QST" in which the author also mentioned migration as a cause of death for incandescent lamps being run on DC. Martin McCormick WB5AGZ Stillwater, OK OSU Information Technology Division Network Operations Group