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Author Topic: 40 meter Double Bazooka Vs 80 meter ladder line fed doublet  (Read 7489 times)

KE7TRP

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This test is a 40 meter Double Bazooka wire antenna made from RG11 coax VS an 80 meter open wire line doublet.  The Doublet is from Trueladderline.com and uses 600 ohm feedline. The antenna is hooked to a Johnson KW matchbox balanced tuner. The Doublet is at 40 ft.  The Double bazooka is at 30 ft.  The DBZ has a lot less noise with stronger signal than the Doublet.


I took this video today.

http://youtu.be/_nWCGKyOSqk

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KE7TRP

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Re: 40 meter Double Bazooka Vs 80 meter ladder line fed doublet
« Reply #1 on: August 03, 2013, 12:04:41 PM »

I did some more testing.   I used glSDR application on my Android smart phone to access SDR receivers all over the world and US.   glSDR has a full band scope and water fall display.  I sent out a signal using my Call Sign on open frequencies and tuned the Remote receivers to match. In most cases the 40 DBZ is the same as the Open wire line doublet.  I don't see much difference , Sometimes there is a few DB higher on the DBZ. But for the most part it is a wash. I attempted to access each 360 degrees from my station. Since I am south west, This is difficult, However, I do not see any real difference broadside to end fire. I think this is because the antennas are pretty low on the nested tower.  I am really enjoying the significant decrease in noise with the DBZ and the lack of feedline radiation and interference over electronics.
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K3DAV

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Re: 40 meter Double Bazooka Vs 80 meter ladder line fed doublet
« Reply #2 on: August 03, 2013, 07:27:49 PM »

Low noise floor or higher noise floor.  Hmmm which one would I chose?  LOL

Most antennas of similar design do not make much difference, (if any) out beyond the curve of the Earth.  But the fact that there was a signal increase in the receive must also work in the opposite direction on xmit.  As little as the increase may be, it is only common sense that an antenna that receives better should transmit better.

But even if the difference is very small and nobody listening might even notice it, you have to admit that lower noise floor alone is worth all the effort.  That's the magic of DC grounding with a dipole.  Some of the local QRN goes to ground instead of your receiver.
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KE7TRP

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Re: 40 meter Double Bazooka Vs 80 meter ladder line fed doublet
« Reply #3 on: August 04, 2013, 08:17:48 AM »

Yes. Over the last few years the noise in the neighborhood has increased to the point where I looked for another antenna.

I took the tower down yesterday.  I put the 40 DBZ north and sound one section down from the top.  The top holds the 80 DBZ east and west.    This way they are 10 ft apart and 90 degrees. 

One of us taped the beams coax to the second section when we taped up the coax for the 40DBZ. So when I cranked the tower up today, it ripped the coax connector out of the lead that runs to the Mosely beam.  ARRRGH!  I got the tower all cranked up, secured and ready to get on the air, had no RX on the beam, Walked outside and found the coax dangling 60 ft in the air. 

After I cool off, I will have to take the entire tower back down and repair it.
C
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