I have a flag antenna which has worked well for several years. I used a
Minicircuits T16-6 transformer to couple the ~800 ohm termination resistance of
the antenna to 50 ohm line. Recently I decided to do some upgrades, so I
followed the recommendations of many (here and elsewhere) and made a matching
transformer using an FT-140-43 core and 34:8 turns, secondary and primary on
opposite sides of the core. I didn't have any #28 wire so I used #24. I tested
this with a miniVNA, terminating the antenna side with an 800 ohm noninductive
resistor. The impedance does not look right at all; there is a lot of inductive
reactance and the resistive part starts at 125 ohms and climbs steeply from 1.7
MHz. No on-the-air results yet.
I'm wondering if this is right or not - measurements indicate the DIY
transformer is much worse than the T16-6 in terms of presenting a good match.
This would not be the first case of theory saying it won't work but practice
says it will - just looking for a reality check here. Seems to me like the core
material is all wrong...
-Tony, K1KP
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