[Amps] Shunt resistors for a bridge made of 6A10 diodes in

[Ian White]

Every modern rectifier diode *is* an avalanche diode, meaning that reverse
breakdown (if it happens) is in a low-current, non-destructive avalanche
mode. 

That had already been true for some time before the ARRL Handbook changed to
no longer recommending the use of equalizing components... and even that was
20 years ago. (I checked with the original author at the time.)



73 from Ian GM3SEK


-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Bill Turner
Sent: 03 February 2016 18:15
To: Amps group
Subject: Re: [Amps] Shunt resistors for a bridge made of 6A10 diodes in

------------ ORIGINAL MESSAGE ------------(may be snipped)

On Wed, 3 Feb 2016 12:15:45 -0500, K5GW wrote:

>Avalanche diodes do not need to be identical. The diodes are in series 
>so the reverse leakage current is the same in all diodes. When a diode 
>reaches the  avalanche voltage the voltage drop stabilizes much like a 
>zener diode does.
> 

REPLY:

As I understand it, all diodes have an avalanche (zener) voltage. The
question is whether it can withstand the power dissipated at that voltage
and reverse current. A diode which is not specifically designed to operate
in avalanche mode may fail. 

Better safe than sorry, IMO. Either match them by batch or use equalizing
resistors. 

Even better, use one of the encapsulated 20 kV diodes mentioned in an
earlier post. Four of them are less than $12.

73, Bill W6WRT
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