[Amps] HV Supplies and Diodes

[TexasRF at aol.com]

Amen Brother!
 
73/k5gw
 
In a message dated 1/2/2008 4:48:23 P.M. Central Standard Time,  
km1h at jeremy.mv.com writes:

I find  it a bit strange and somewhat comical that the only ones that appear 
to  champion resistors and capacitors across any series string of 1N540x  
diodes is the amateur community.

Not one manufacturers application  notes mention them.

No industrial product that Im aware uses  them.

The one ham amp manufacturer mentioned has a reputation of power  supply 
problems.

Most of us realize that the diodes of the 60's had  problems but is there any 
reason to continue it almost a half century  later?

Fact or  mythology?

Carl
KM1H





----- Original Message  ----- 
From: "Jim Tonne" <tonne at comcast.net>
To: "Dennis W0JX"  <w0jx at yahoo.com>; <amps at contesting.com>
Sent: Wednesday,  January 02, 2008 2:20 PM
Subject: Re: [Amps] HV Supplies and  Diodes


>
> When a string of series-connected diodes is  reverse-biased
> (during part of the cycle), the voltage drop across one  is
> proportional to its leakage resistance.  If the junction of  the
> diode type has significant capacitance, then that enters  into
> the picture too.
>
> If you use, in parallel with  each diode, a resistor whose value
> is a fraction of the leakage  resistance, then those resistors will
> swamp the leakage and so tend to  equalize the voltage drop
> across each diode in a  string.
>
> If you use, in parallel with each diode, a capacitor  whose
> value is several times that of the junction, then those  capacitors
> will swamp the junctions and again tend to equalize the  voltage
> drop across each diode in a string.
>
> During the  forward-conduction part of the cycle of course
> we have no problems  with any of the above.
>
> I am not familiar with the rules on  avalanche diodes.
>
> - Jim WB6BLD
>
>
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>  

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