Without knowing what manufacturer and their designation, I can't answer the
questions specifcally. But, I do have a recent CDE catalog and the RF
current ratings for some of the small radial leaded micas is surprisingly
high....but not in all cases. Here's some info for comparison :
The RF current rating changes with the Series of product, and the different
Series appears to denote different physical sizes and voltage ratings.
Current rating goes up with size, voltage rating and frequency.
For example, a 220 pf cap in the CD15 Series (500VDC or 300 VAC) will
handle 0.6 amps continuously at 5 Mhz. These measure 0.46" L x 0.38" high.
A 220 pf cap in the CDV19 Series (1000 VDC or 350 VAC) will handle 1.4 amps
continuously @ 5 Mhz. These are 0.64"L x 0.50"H.
A 220 pf cap in the CDV30 Series (1500 VDC or 400 VAC) will handle 2.8 amps
cont. @ 5 Mhz. A 2200 pf cap in this same series will handle 5.5 amps.
This series of caps measure 0.77"L x 0.88"H, and are 0.25" thick.
The quarter inch caps Vic mentioned compare (size wise) to the UHF caps in
the CDE catalog. No RF current rating is given for these, which implies
that caps this size weren't intended to handle much current on a continuous
basis. But they may survive anyway since the intended duty cycle is
considerably less than "continuous", and they will probably be in moving
air to keep the temp down.
I might suggest that you consider buying some of the CDV series caps, and
go for the highest voltage rating available for the capacity you want.
Either Mouser or DigiKey carry these.
Phil
At 03:47 PM 10/24/1999 -0500, you wrote:
>
>> I'm putting together the input pi-nets for my 2 x 3-500z amp. The input
cap is
>> a trimmer, and the output is fixed.
>>
>> For some of the values of output capacitors, I have 500v dipped silver mica
>> capacitors, and the smaller values (150-100 pf) are really physically
small --
>> like 1/4" long. Do these capacitors carry a significant amount of
current, and
>> would I be advised to look for larger capacitors? In the higher values,
I have
>> some old-fashioned capacitos about 1/2" x 3/4" in size.
>>
>> 73,
>> Vic, K2VCO
>> Fresno CA
>>
>
>Sounds good to me, Vic. That is all Heathkit ever used.
>I don't recall ever seeing the current rating on 500v micas.
>Maybe someone can tell us.
>
>(((73)))
>Phil, K5PC
>
>
>
>
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