looking to make a balun to go from 450 to 75 ohms at vhf frequencies. cant locate any designs on internet
Wind 6 turns #28 wire on a T50-12 core for the 75 ohm winding and 15 turns for the 450 ohm winding. This should be close but the turns may need to be adjusted. Just keep the ratio 1:2.5 and use a toroid core suitable for the frequency. Wire size isn't critical as long as it fits in the core.
Neil
any idea why ramsey uses 450 ladder line with a 4:1 balun on their tm 100? seems that would give you about 100 ohms on the primary not 75 ohms.
In one hand I've got Radio Handbook opened to the Index, and under "Balun" I see three categories: feed system; transformers; and wideband.
There are many pages devoted to many configurations of unbalanced, balanced, 1:1, 1:4, 1:9 for many different styles of antenna and various frequencies, but I do not see the particular balun specs you are hunting for.
OH,HEY: While I was typing this with my free hand, Radio8Z provided the exact information you needed, so everything is good.