On Mon, 28 Sep 1998 11:23:18 -0700 "Radiodan W7RF" <RFpower@radiodan.com>
writes:
>
>Hi Carl and Igor,
>
>Why such a mess?
>
>This insistance on using electrolytic caps in such quantities puzzles
>me?
>
If you noticed in my initial reply I suggested that oil caps can be found
at a reasonable price. The last one I purchased was 51MF @ 10KV that I
can barely lift but it only cost $40.
I did not realize the Henry cap was so cheap and that certainly is an
attractive choice; thanks for mentioning it.........altho it wont fit
with Igors 9+ KV plan.
Electrolytics are an option to consider where availability is a problem
with oil but my stress was the type and quality of the electrolytic.
73 Carl KM1H
>HENRY uses a single 16UF @ 8KV oil filled and is available for $125
>(new).
>This is less than the computer caps in the quanties needed and is
>superior.
>Probably smaller too.
>No equalizing resistors or worry about matched units. No concern about
>how
>much current to draw through series devices or cooling.
>
>There are virtually no disadvantages to oil over electrolytics.
>Igor, it sounds like you're making a "real" amp. Most manufacturers
>use
>computer caps because at lower voltages they are cheaper in the toy
>desktop
>models.
>Your real amp voltages require a real capacitor.
>
>Oil filled caps are not too expensive or hard to find. You just found
>one.
>Someone may have an oil filled to sell you cheaper.
>
>73 Dan Magro, RADIODAN W7RF, (member SCDXC)
>Henry HF Amps are "Instant on" for RF Power now!
>Rugged, Reliable HENRY RF Power Amplifiers for LESS!
>Trust one of your own, a DXer & Contester.
>http://www.radiodan.com??? RFpower@radiodan.com
><mailto:RFpower@radiodan.com> A trip to our web site is worth the
>click!
>
>
>
>
>> -----Original Message-----
>> From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On
>> Behalf Of km1h@juno.com
>> Sent: Monday, September 28, 1998 7:24 AM
>> To: amps@contesting.com
>> Subject: Re: [AMPS] Series Parallel Electrolytics & Current
>>
>>
>>
>>
>> On Sun, 27 Sep 98 18:36:26 -0800 Rich Measures <measures@vc.net>
>writes:
>> >
>> >>Hi Rich
>> >>
>> >>I am sure I am just missing something but what are the DIGI-KEY
>part
>> ># for
>> >>the 105 degree 470uF Caps. ......
>> >
>> >P10170-ND. Thanks for the heads up, Paul. I intended to put
>this
>> >in the article.
>> >>
>> >>> 105º deg C rated electrolytic capacitors last much longer than
>85º
>> >C
>> >>rated electrolytics. - - I would use 2x 24 Panasonic
>[Matsushita]
>> >>470uF, 450v, 105º C rated units in series parallel. This would
>> >deliver
>> >>about 40uF @10.8kWV. I would use one 100k ohm, 3w equalizer
>resistor
>> >>across each pair of paralleled 470uF units. It is my opinion that
>> >for SSB
>> >>operation, less C would work ok. Also, I would mount the
>individual
>> >>electrolytics on a 7mm or more-thick acrylic sheet with silicone
>> >rubber adhesive to reduce
>> >>case stress. (Digikey currently sells these caps. at c. $12.20
>each
>> >in
>> >>10 unit quantities.)
>> >>>
>> >rong. Current pricing is $13.85 ea. for 10 - 99 units.
>>
>>
>> Identical rated caps made in the USA by CDE are available from
>Mouser.
>> Part # 381LX471M450A052 ( Mouser # 5985-450V470) are $11.29 ea Qty
>> 10-99.
>>
>> These and the Panasonic are good caps but be careful of the ESR and
>> ripple current ratings which are signifigantly worse than computer
>grade
>> caps.
>> Mouser carries the Mallory line of CGS and prices are just a little
>bit
>> more than the smaller caps.
>> If you design for less C as Rich suggested you can save quite a bit
>of
>> money.
>> Mouser also carries 3 and 5W MOX resistors.
>>
>> BTW, I find that Mouser almost always has better prices than
>Digi-Key.
>>
>> 73 Carl KM1H
>>
>>
>>
>>
>>
>> >>>> Oil capacitors are
>> >>>>hard or too expensive to find. The Current rating of most
>> >>>>electrolytics are around 1 amp, how would they operate at this
>> >current?
>> >>>
>> >>> At 3A on RTTY, Hot. The solution is to use paralleled units
>to
>> >divide
>> >>the ripple current burden. It's not a bad idea for electrolytics
>to
>> >be
>> >>mounted with air gaps and to use a bit of forced air cooling.
>> >>>>
>> >>>>
>> >>>- later, Igor
>> >>>
>> >>>
>> >>>Rich. Measures. Web site: www.vcnet.com/measures
>> >>>
>> >>>
>> >>>--
>> >>>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
>> >>>
>> >>Paul J Hellenberg W9JA ex KS9K Tru Line Lithographing Inc.
>> >>PO BOX 565 7900 Durand Av., Sturtevant WI 53177-0565
>> >>414 554 7300 -125 Fax 414 554 8217 Home 414 554 9170
>> >>http://www.contesting.com/Tours/W9JA/w9jahome.htm
>> >
>> >
>> >
>> >Rich...
>> >
>> >R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>> >
>> >
>> >--
>> >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
>> >
>> >
>>
>> ___________________________________________________________________
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>>
>
>
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>
>
___________________________________________________________________
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Problems: owner-amps@contesting.com
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