[Amps] Resistor Types

[Bryan Swadener]

> Date: Thu, 21 Jun 2007 11:27:12 -0400
> From: Garry <g.drummond at verizon.net>
> Subject: [Amps] Resistor Types
> 
> Hello,
> 
> I am replacing the filter caps in the power supply
> of an Alpha 78 and 
> will probably replace the resistors as well. There
> are two paralleled 
> 120K ohm 3-watt resistors across each cap now.
> 
> Would it be best to replace these with MOF resistors
> or stay with same 
> carbon type?
> 
> Thanks,
> Garry - WR4R

Hi Garry,

Likely, the biggest concern is the voltage rating of
the replacements.  You can be under the power
dissipation limit of a resistor and at the same time,
be above the voltage limit (until it arcs over).  I
recently bought some 100K/1%/5W resistors (Vishay/Dale
#RS005100K0FE73) from Digi-Key to replace the 8 x
30K/10W resistors in my SB220.  The HV is about 3200V
no-load.  The resistors are rated 1KV, while each
resistor will see about 400V max.

73,
Bryan WA7PRC


       
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