[Amps] High grid current and No kathode current, known triode failure mode ?

[pc5m, Carel]

Hi,

 

Al of a sudden I experience with my gs35b triode amplifier  the condition of
High (200mA) grid current and NO kathode current when applying only PTT (do
drive).  Also the powersupply indicates the same current drawn. Amplifier
has only be transported between last time it functioned ok. Nothing changed
(same HV PSU, etc).

 

Grounded grid configuration, drive applied at cathode. 

 

Did perform some measurements on the metering ciruit, etc and al seem to be
ok.

 

Question: Is this a known fault condition of a triode ? (high grid current,
no cathode current when biased with zener applied between cathode and
ground) and could that be due to mechanical vibrations ?

 

Thanks in advance,

 

Carel, pc5m