[Amps] Filament forces

[Alek Petkovic]

Also for those interested, another side of the coin.

Bill Orr, in an article called "Long Life for Your Amplifier Tubes" 
in Radio Fundamentals, CQ January 1991 describes a case of repeated 
grid - filament shorts with 3-500Z tubes. An amateur had the filament 
supply connected to the vox/ptt line and this constant on off cycling 
was deemed to be the cause of failure of 6 tubes in the space of a few weeks.

I have a copy of the article here and can provide a .pdf of same to 
anybody who wants it.

73, Alek
VK6APK

At 10:10 AM 28/08/2006, Tom W8JI wrote:
>For those who are interested:
>
>1.) The filament starting current can easily be 30 or 40
>amperes RMS (50 amperes peak) for thousands of turn on
>filament cycles and not cause damage. As a matter of fact
>when Eimac tried to simulate inrush damage to 3-500Z's they
>clamped a 200-amp transformer right to the pins of tubes and
>cycled them over and over again without any sign of damage.
>

http://www.qrz.com/vk6apk