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@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
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|