Ham Operator Forums

Thanks C, I still don't have the shack finished so I'm not on the air yet. That's good to know about the caps and yes I'll have 220 available when I do get things going. I will have the case opened first and blow the cow-webs out and clean up the dust. Also will check the caps for any leaking. I was just worried that since it hasn't had any power applied for the past 18-20 years that the caps might of dried out. I'll let you know when I do get it running. Thanks again.
73's Jim

I have a problem with SWR on the 80 meter DBZ.  I had it tuned very flat.  I then installed it on a Fiberglass Arm of the top of the tower,  Now the minimum SWR is 1.8 to 1.  I swapped feedlines with no change.  I moved the legs around with little change. 

I had this same antenna and feedline pulled up the tower with rope and pulley to the same hight and the match was low. Now its high.  I have exhausted Ideas for now. 

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.

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.

Clark, one of the reasons the 75 meter DBZ is not as broadbanded is because you used RG-11  75 ohm coax to make it.  75 and 160 meters are very picky with that kind of thing.  And if you used the RG-11 for the 40M DBZ, I am a little surprised that your SWR is that good, but then again 40 meters is not as picky.

Bazookas work best with regular basic RG-8 or RG-8X.  Bazookas love leaky coax.  Coax with tight shields do not perform as well,  And never use a coax with a foil lining around the foam insulator to make a Bazooka.  They still work but they are nowhere near as broadbanded.

It sounds like the 40M DBZ is going to work out very well.  Mainly you will notice weaker signals seem a bit cleaner because of the lower noise floor as your video shows clearly.  I watched your meter closely as you switched between antennas, and I think I saw a slightly higher signal on the Bazooka.  Not a big difference mind you, but that lower noise floor alone makes it worth it.  The choice of LMR-400 for feedline is a good idea.  That is the only coax I use these days.

Good goin' Clark.