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 > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
