[Antennas] Simple Dipole Question

[Chris Adams]

Kelley,


I would be concerned with the following issues:

1).  It's possible that the  balun is getting saturated if the mismatch 
is large enough so I would reduce power and see if that has any effect 
on your SWR.

2).  A tuner is advisable, does your rig have one?  

I have the exact same setup as you do except the dipole is 40m, I don't 
know how long the ladder line is and I do use the balanced to unbalanced 
transformer in my MFJ tuner to go from ladder line to coax instead of a 
balun.  I do NOT use the MFJ tuner (bypass mode) but do use the tuner in 
my rig.  It is easily matched on 40m.

3).  At 14.2 MHz a wavelength is about 66 feet.  The load impedance 
(i.e. antenna impedance) should repeat every 1/2 wavelength and your 450 
ohm transmission line is about 1 1/2 wavelengths.  Taking into account 
the velocity factor of the transmission line your 450 ohm ladder line is 
greater then 1 1/2 wavelengths.  That said, I would be surprised that 
you get no type of null in SWR.

4).  I would suggest you double check your coax, connections and balun, 
I would vote for something simple wrong like shorted coax or an open or 
short in one of your connections.

5).  I strongly disagree that the ladder line has any effect on the 
length of your antenna.

73

chris, n4vi


Kelley Shaddrick wrote:

>Today, with nothing better to do, I stuck up a dipole cut for 20m (14.2 MHz)
>using 468/frequency. It's strung between two trees at about 50 feet in the
>air. I fed it with ladder line (450 ohm) to the house (about 100 feet) to a
>1:1 balun and some RG-8X (about 20 feet) into the 2nd floor shack. The
>initial swr reading is infinite across the band, no dip anywhere, not even a
>little. I suppose since I'm using ladder line, or window line, I need to cut
>things different. Any thoughts?
>
>Thanks,
>
>Kelley -- W�RK
>
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