RE: Balun question
Posted by
Don Wilhelm-3 on
Apr 07, 2005; 1:21am
URL: http://elecraft.85.s1.nabble.com/Balun-question-tp376719p376721.html
Vic,
If my calculations are correct, YES you should have a good balun. The
reactance of the 9 turns is 809 ohms (AL value is 884 mH/1000 turns,
inductance for 9 turns should be 71.6 uH) which is more than 16 times the
impedance of an antenna feedline of 50 ohms. Greater than 10 times the line
impedance is the value I usually use for an effective chokeing action.
73,
Don W3FPR
> -----Original Message-----
>
>
> I made a simple 1:1 receive-only balun for 160 meters by winding
> 9 bifilar turns
> of no. 24 enameled wire on an FT37-77 toroid. I connected a
> 50-ohm resistor to
> the output and my MFJ antenna analyzer to the input. On 1.8 MHz
> it shows a
> resistance of 50 ohms, an inductive reactance of 1 ohm, and an
> SWR of 1.0:1.
>
> My question is, did I make a 'good' balun? Are there other tests
> I should do?
>
> It's job will be to isolate a receiving loop antenna from its
> feedline, to keep
> the nulls deep and reduce noise pickup.
>
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