[Amps] Metal-Clad Resistors

[HAROLD B MANDEL]

Gentlemen,

A previous posting mentioned Vishay (or equiv.)
metal-clad, bolt-down resistors as maybe
candidates for anode protection, and a further
comment from AG6K warned against using
these, and to this I must heartily agree.

Firstly, the metal-clad resistors may not 
have the HV capability. There may be
an internal arc inside the resistor.

Secondly, when a pulse situation arises
the metal cladding may prevent the 
small amount of physical distortion
severe heating produces that a bigger
resistor may be able to withstand.

Thirdly, Mr. Measures' observation
about the resistor becoming a cannon
is entirely plausible.

A 50, 100 or 225 watt resistor,
surrounded by a cage might still
blow up, but like changing a split-rim
truck tire, the cage may be a lifesaver.

Hal
W4HBM