[Antennas] New OCF Dipole

[Bill Kulze]

Thanks to everyone for the encouragement. It is a great feeling to put 
something together yourself and have it work.

As far as the balun is concerned, I don't think I have a problem with it 
handling frequencies down to 80m. At 3500kHz the match is almost flat. 
 From what I've read, the length for the center of 80m would put 
resonance above the center of the other bands. A couple designs use a 
100pf to 200pf cap in series with the long leg. I put in about 220pf and 
it raised the upper 1.5:1 point to about 3900kHz. I thought that more 
capacitance might make it seem shorter, so I raised it to about 450pf. 
Didn't solve the issue, actually made the match a little worse. So, I'll 
be putting it back to 220pf and I'll try folding back some of the length 
to bring it up more into 75m. What I'm wondering is if I will see a rise 
in swr in the cw portions of the other bands. I think at the very least 
I will wind up getting a tuner to assure a good match. I built one, but 
even though my caps came out of old tube receivers, they are still not 
capable of the voltages present. I got some arcing out of it the other 
night. It does work though. It started out as an L-match for use on the 
end fed I have up. I kinda followed an old arrl book for the End-fed 
Hertz I think they called it. When I have the tuner in the cellar near 
the feed point as they show, I can tune it pretty much flat, but my 
shack is on the second floor. I have to bring the whole rig to the 
cellar to tune it! Anyway, I converted it to a T configuration and it 
tunes, but I get the occasional arcing that I mentioned.

This weekend I plan on building the A-frame mast that's in the antenna 
book. That should get the center up to about 35ft. If the weather is 
bad, I should get a real high performance antenna! I think I have a good 
start...

Bill KC2SUO

Charles Greene wrote:
> Bill
>
> I don't think a t200-2 has eno[ugh permeability for a balun on 80 
> meters,   That might be your prob.  My Ocf is > 2:1 across the 80 
> meter band using those dimensions.  Try a 4:1 balun using a f140-43 
> core, of better yet, two.
>
> Chas W1CG
>