Topband: Flag/Pennant Question
Earl W Cunningham
k6se at juno.com
Thu Feb 8 14:59:37 EST 2007
Jeff, KU8E wrote:
"I ordered a FT-140-43 toroid and some #28 enamel wire from Amidon to
build a match transformer. Hopefully I will get it by Monday since I am
leaving for PJ4 on Tuesday morning.
I have a FT-240-43 laying around. Can this be used as a substitute if I
don't get my order from Amidon in time ? How many turns would I need on
the primary and secondary?"
Yes, you can use the larger FT240-43 toroid core. For 50-ohm coax, Use 8
turns for the low-Z winding and 34 turns for the hi-Z winding. For
75-ohm coax, 8 turns and 28 turns is correct.
Since the Flag/Pennant article, is has been determined that type 73
material is a better choice for the core, and a binocular core is best.
For type 73 material and 50-ohm coax, use 2 turns for the low-Z winding
and 8 turns for the hi-Z winding. For 75-ohm coax, use 2 turns and 7
73, de Earl, K6SE
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