[Amps] ps caps

[Vic K2VCO]

Actually, it's quite possible that they are matched.  The voltage across 
series capacitors will divide unequally depending on the capacity and 
the leakage resistance.  If there are 20% tolerances, this can be a big 
difference.

Part of the function of the equalizing resistors is to swamp out these 
voltage differences (they also serve as bleeders).  If the capacitors 
are not matched, the resistors across the ones with lower capacity 
and/or higher leakage resistance will run hotter than the others.

If the amp is designed to use capacitors that are matched to within, 
say, 5% for leakage and capacitance, then they could use higher value 
resistors which would be less effective in swamping the voltage 
differences.  This would cause some of the capacitors to operate at 
higher voltage than others.

I would believe what Alpha is telling you.  I doubt that a large part of 
their revenue comes from selling replacement capacitors!

Gary Smith wrote:
> Sounds to me they want to match their profit on each capacitor they
> sell. 73

> Gary...wa6fgi

> Will Matney wrote:

>> Do what?
>> 
>> They buy those like any other manufacturer by the case or how many
>> they need. I'll guarantee they don't take the time to grab each
>> capacitor and check it for capacitance, ESR, and leakage on an
>> assembly line, then try to match them up! The ones at Mouser are
>> just as good no matter what anyone tells you, period.
>> 
>> I thought I'd heard the BS before from manufacturers, but that
>> claim reminds me of those audio amp manufacturers. Ask Alpha if
>> that means your audio will sound any better, LOL!!!
>> 
>> Best,
>> 
>> Will

>> *********** REPLY SEPARATOR  ***********

>> On 8/21/05 at 4:20 PM hcawthra at sbcglobal.net wrote:
>> 
>> 
>> 
>>> I need a opinion. I want to replace the filter caps in my Alpha
>>> 78 amp. Alpha wants $30 ea for the caps mouser wants $16.40 ea
>>> for the exact same part number. Alpha claims caps are matched.
>>> Any ideas. 73 Howard KA6IOB

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco