To: <amps@contesting.com>
>Date: Mon, 08 Feb 1999 10:18:44
>To: "Will K6NDV" <k6ndv@contesting.com>
>From: "William L. Fuqua III" <wlfuqu00@pop.uky.edu>
>Subject: Re: [AMPS] 470uF/450v caps for $2.25
>
>Well, after seeing all the flak I would like to add
>a few comments.
>
> 1. When you series capacitors that are not all the
> same exact capacitance there is a different voltage
> across each. Those with a spec such as +80%-20% can
> be a problem if you don't series enough to allow for
> this error. Remember V=Q/C...... If V is changing quicker
> than the time constant of the resistors across the
> capacitors (ripple frequency, SSB or CW operation, SPARKS etc)
> the voltage across the capacitors may not be the same.
> And if you have too few in series one may break down and then
> cause a cascade of failures until all are lost.
> I plan to use 20 capacitors for a 6KV power supply.
> At this price it and the space I have available it is
> no problem. That also means that I have a 50% safety
> margin and these are supposed to be 20% tolerance caps.
> Maybe I'll add 4 more just for good luck. That is
> over 10KV worth.
> I have seen many power supplies built such that if
> one capacitor shorts out the power supply voltage then
> is greater than the total ratings of the capacitors left.
> I just see no reason to cut it so close.
>
> 2. Don't put them where they may get. Near power resistors,
> plate tank circuit or tube etc.
>
> 3. Do check their capacitance and leakage before installing
> them.
>
> 4. And have plenty of shielding around them just in case one or
> more do go. Electrolytics will go bad some day. You can bet
> on that.
>
> 5. I have not used these and if you want you may look up the
> characteristics in a catalog yourself. These are not real
> old like the stuff we find at ham fest or used equipment.
>
>
>At 12:35 PM 2/6/99 -0800, you wrote:
>>
>>ok......SIZZLE and BANG .....
>>seen a few email about these caps and wonder who installed them with good
>>result.
>>I just can not belief that these caps. are not meeting any standard.
>>Will, K6NDV
>>
>>-----Original Message-----
>>From: km1h@juno.com <km1h@juno.com>
>>To: amps@contesting.com <amps@contesting.com>
To: <amps@contesting.com>
>>Date: Saturday, February 06, 1999 11:22 AM
>>Subject: Re: [AMPS] 470uF/450v caps for $2.25
>>
>>
>>>
>>>
>>>
>>>On Fri, 5 Feb 1999 16:09:16 -0800 "Will K6NDV" <k6ndv@contesting.com>
>>>writes:
>>>>Carl, please explain the unpleasant result.
>>>
>>>
>>>>Thanks Will, K6NDV
>>>
>>>SIZZLE and BANG
>>>
>>>73 Carl KM1H
>>>
>>>
>>>
>>>
>>>
>>>>
>>>>.
>>>>>>The catalog price is 10/$40....
>>>>>>
>>>>>>73
>>>>>>Bill wa4lav
>>>>>]
>>>>>
>>>>>
>>>>>These were mentioned many weeks ago when the ALL ad first appeared.
>>>>>
>>>>>Good luck in using them in high ripple current HV supplies;
>>>>particularly
>>>>>voltage doublers. I bought several ( always looking for a REAL
>>>>bargain)
>>>>>and tested them in a SB-220...the results were not pleasant.
>>>>>
>>>>>73 Carl KM1H
>>>>>
>>>>
>>>>
>>>>
>>>
>>>___________________________________________________________________
>>>You don't need to buy Internet access to use free Internet e-mail.
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>>>
>>>--
>>>FAQ on WWW: http://www.contesting.com/ampfaq.html
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>>>
>>>
>>
>>
>>--
>>FAQ on WWW: http://www.contesting.com/ampfaq.html
>>Submissions: amps@contesting.com
>>Administrative requests: amps-REQUEST@contesting.com
>>Problems: owner-amps@contesting.com
>>Search: http://www.contesting.com/km9p/search.htm
>>
>>
>
William L. Fuqua III P.E. E-mail WLFUQU00@POP.UKY.EDU Phone (606) 257-4155
Department of Physics and Astronomy CP-177 Chem. Phys. Bldg.
University of Kentucky , Lexington, Ky 40506-0055
--
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