[AMPS] Henry 2K2

Ian White, G3SEK G3SEK@ifwtech.demon.co.uk
Tue, 11 May 1999 20:47:04 +0100


Picking up on one of Rich's remarks:

>Henry's glitch-R in the neg. HV 
>lead is a mistake.   A glitch R should be added to the pos. HV circuit.  

It doesn't really matter which end of the HV circuit the glitch resistor
and HV fuse are - unless the designer thinks that putting them in the
negative return rail requires less insulation. In fact it requires
*more* insulation, because a "crowbar" short from HV+ to chassis will
tend to push the return rail down to *minus* the normal HV. 

To avoid breakdown, the negative rail and the negative end of the
capacitor stack therefore need to be insulated to the same standard as
the positive end.

A certain line of amplifiers has the fuse in the return rail, with
ordinary hookup wire running back to the capacitors through a hole in
the chassis - not even a grommet.

73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)
                           http://www.ifwtech.demon.co.uk/g3sek

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