Plus biasing heater (220vdc above ground)

[Bas Horneman]

My question is am I doing long term damage to the tube?
Ie does the heater cathode insulation spec also pertain to negative difference.

Usually the heater cathode insulation pertains to the potential of the cathode ABOVE heater..but now it is BELOW......... but by a margin that is above heater cathode insulation spec.

A little sidenote is...that is sounds very very good this way...

 

[fdegrove]

HEATER TO CATHODE INSULATION.

Hi,

Usually the heater cathode insulation pertains to the potential of the cathode ABOVE heater..but now it is BELOW.........

+ or - doesn't matter,you should measure between heater and cathode.
Not with respect to ground.

Cheers,

 

[Bas Horneman]

Thanks Frank..

Thought so...what is the damage being done actually?

Chees,
Bas

 

[fdegrove]

HEATERS.

Hi,

Thought so...what is the damage being done actually?

At first you'll hear the valve go into HF oscillation, some report LF oscillation but I never heard of that.

In the long run the heater and cathode will "stick" creating a short.

Cheers,

 

[Bas Horneman]

Heater / Cathode insulation

I just supposed that I am over the specs...but a look at the 6n1p datasheet does not reveal the max rating..

Anyone know?

 

[fdegrove]

HEATER.

Hi,

but a look at the 6n1p datasheet does not reveal the max rating

6N1P 100V
6N1PVI 120V
6N1P-EV 120V

Cheers,

 

[Bas Horneman]

You're fast Frank!

Thanks..

While I've got your attention...I've been thinking about a 6EW7 spud amp...but can get the 6DE7 cheap..and it looks very similar...Do you thing it is a good alternative to the 6EW7

Cheers,
Bas

 

[fdegrove]

SPUD.

Hi,

The 6DE7 powertriode triode section has a max.dissipation of 7W
whereas the 6EW7 can disspitate 10W.

Other than that...up to you.

Cheers,