[Lowfer] 185.300 again

[Bill Ashlock]

>I think he is using an untuned HF vertical now.

Yah, I think that's right. Probably close in characteristics to my untunned 
tree antennas - which really work well and don't require any attention.

>I was thinking a tuned LF antenna would be quieter.

I used to think that way, too, but my antenna tests don't seem to support 
this thinking. For sure, the  higher the loop Q the higher is - the higher 
the signal level is, so pre-amplification is often not needed. Probably 
receiverers easily overloaded by out-of-band signals are helped with tuned 
loops, but most of the the receivers we use don't need this.

>I see your point on big loops for RX work but my North/South loop received 
>way lower noise than >the flattop did.

That's interesting, probably your local noise was more E-field based than 
H-field, or possibly you were picking up noise on the flattop antenna via 
the ground system connection. Noise sources can be very complex at times.

As an example I'm about to head back to see a friend of mine that has an 
incredible amount of power line noise at his base. He originally got 
interested as a LF listener when his noise was much lower and he could copy 
WA with ease. Then, he would get intermittent bouts of noise that would be 
20db stronger than WA, and eventually the noise was present 100% of the 
time.... and the power Co couldn't find a problem. The last time I was down 
to see him we showed that an E-probe elevated in a tree in the back corner 
of his land was almost noise-free on WA when connected to my portable SVM. 
But when a lead-in was used to transport the signal back to the SVM located 
in the house, the noise was again +20db. My theory is that the lead-in is 
actually transporting the power line noise at the house out to the antenna 
site, even though there was no connection from lead-in to his house gnd. The 
next time I go back I'll be armed with a number of 1 to 1 isolators for the 
170ft of  lead-in and parts for a tree antenna (wire, matching xfmr, gnd 
rod, etc), which doesn't require  DC power via the lead-in, like the 
E-probes do. Luckily he just bought an R-75 so the receiver should be 
adequate to match up with the somewhat lower signal from the tree antenna 
compared to an E-probe. Should be fun!

Bill

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