[600MRG] WIMA capacitors

[Ben Gelb]

Yeah I would only ever bother with MLCCs for rf... not the leaded ones. I
think they should pretty much be lowest ESR available... but agree there
might be a cost issue that doesn't always make sense.

I think the one I linked is available in 6.8nF though... which might be
usable for OP's application (at $1.67, not sure how would compare to WIMA
caps).

On Fri, Jan 5, 2018 at 7:15 AM, Larry <larry at w7iuv.com> wrote:

> I have tried ceramics.
>
> The usual disk ceramics are horrible.
>
> The big transmit ceramic "doorknobs" can be used in some applications but
> are usually not much better.
>
> Some C0G/NPO chip ceramics are OK for receive applications if you don't
> mind your filters being a bit lossy. The real issue with chip caps is that
> the good ones are just not available in the large values needed for
> 137/475. The "good" ones run 2 or 3 bux apiece and it makes little
> financial sense to parallel a dozen or more to make the required C values.
> Of course if you have access to them at little or no cost, then they become
> more attractive!
>
> 73, Larry - W7IUV
>
>
> On 05-Jan-18 6:16 AM, J Mcvey wrote:
>
>> Ceramics ought to work well, no?
>> Have you tried any of them?
>> There are COG and 5% types ...
>>
>>
>> On Friday, January 5, 2018 8:49 AM, Larry <larry at w7iuv.com> wrote:
>>
>>
>> Recently I had the opportunity to look close at some caps for 475/137
>> filter use.
>>
>> I measured the Q at the approximate operating frequency.
>>
>> The best is silver mica caps. Expensive but usually worth it for
>> critical applications. Unfortunately not usually available in the values
>> needed for 137.
>>
>> Next best is the 715P "orange drops", expensive and sometimes hard to get.
>>
>> Third on my list is the WIMA MKP1 series. Seems to be OK in all my
>> applications so far and is affordable.
>>
>> I have had bad luck using the FKP1 series caps. The ones I looked at had
>> higher ESR, lower Q and got hot in my filters.
>>
>> Kemet and other vendors didn't seem to be much good, at least the types
>> I had access to.
>>
>> YMMV....
>>
>> 73,
>>
>> Larry - W7IUV
>>
>>
>>
>> On 04-Jan-18 10:32 AM, lstoskopf at cox.net <mailto:lstoskopf at cox.net>
>> lstoskopf at cox.net <mailto:lstoskopf at cox.net> wrote:
>>  > Take a look at the graphs for the WIMA FKP1 series.  At 472 kHz they
>> seem to fall off pretty fast.  I'm in the same boat....have some picked up
>> here and there, but haven't used them so anxious to see what the big boys
>> say.  N0UU
>>  >>
>>  >> So I went looking for alternatives. The WIMA FKP1 series is readily
>>  >> available in the proper values and voltage ratings, but I am not
>>  >> sure they can be successfully substituted in this application. Also
>>  >> they are not available in any tighter tolerance than 5%.
>>  >>
>>  >
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