[Amps] B- questions

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Mon, 9 Nov 2009 10:57:46 -0500, "Carl" <km1h at jeremy.mv.com> wrote:

>I fail to see where you obtain a -3000V, perhaps its a terminology 
>confusion.

REPLY:

In a conventional GG amp, both B+ and B- are floating with respect to ground,
except for the connection from B- to ground for the grid current meter. 

If the B+ arcs to ground anywhere and there is no clamping diode, the B- in
instantly driven to the full negative HV with respect to ground. If your HV is
3000 VDC, the B- ;lead becomes -3000 VDC. The clamping diode from B- to ground
prevents this. 

Incidentally, this is why one should never short the B+ to ground when trying to
be sure the HV caps are discharged before working on the amp. Short B+ directly
to B- only, not to the chassis.

73, Bill W6WRT