OK, but there is a huge amount of different materials in ferrites too.
Which kind of material did you use? I've used -61 material in a lot of
high power applications without any problems of them overheating. You
barely feel any temperature raise in them at all if for example using
them as a UN-UN transformer. I like the FT240-61 core very much, it can
handle a lot of power.
Mike, SM2WMV (SJ2W)
http://www.sj2w.se/contest/
On 2011-12-15 14:10, Martin wrote:
> For those who intend to build the FCP INV. L. with a T-200-2 (or an
> antenna tuner).
> Me and a few guys from our club wound different types of baluns and
> chokes on different material and measured them with a
> analyser. We found the T-200-2 next to useless below 3 Mhz due to a low
> AL value (uH/100 turns). The T-200A-2 is a lot better, but still not
> really good in balancing. You better use ferrites (FT-something) as long
> as you use moderate power.
>
> BUT if you go QRO, you should stick with the iron powder cores.
>
> I once replaced the T-200-2 in my homebrew s-match with a ferrite. I
> changed back the same day, cuz after a few seconds with 750W the ferrite
> got so hot you would not want to touch it. The T-200-2 runs cool over an
> entire contest. Next step is to replace it with a T-300A-2.
>
> Below you find a list of cores with their corresponding Al Value.
> You can clearly see that the T-300-2 is even lower than the T-200-2.
> For the FCP INV L. i think a T-300A-2 or even better a T-400A-2 is best
> choice, may it be expensive.
>
> Core Al Value
> T-200-2 120
> T-200A-2 218
> T-225-2 120
> T-225A-2 215
> T-300-2 114
> T-300A-2 228
> T-400-2 180
> T-400A-2 360
>
> I'm not a technician or rf-specialist and english is not my native
> language, so please forgive me if my explanations are a bit ragged.
> Yes, i use a T-200-2 in a tuner, which of course is not the same as an
> antenna, but my feeling tells me i'm on the right track when i say that
> a T-200-2 is no good choice for frequencies below 3Mhz,
>
>
> http://toroids.info
> http://www.qrz.lt/ly1gp/amidon.html
>
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