[Lowfer] Embattled E-Probe

Wed, 08 Oct 2003 03:38:00 -0400

Peter,

I'll concede the war of fancy words; can't even follow much of it,  but I 
disagree with the following, at least in part:

"If noise rises proportionally this is no useful gain." This is only true 
when you reach the point where the input amplifier noise is more than 12 db 
or so below the signal.

My original point with Bob and locating an E-probe in a tree in his front 
yard was that the tree can do no harm and it is a simple way to erect an 
E-probe with a single nylon cord. The signal increases over the 'open' case 
as I indicated, but the 20% gain in signal at 40ft (which is very small) was 
to simply indicate that the tree does NOT reduce the signal (as a good many 
inexperienced LF guys believe). I've done this many times and have shown 
this trick to others who were quite impressed with the results.

The high input resistance of the E-probe allows coupling to the approx 10k 
(summer) distributed resistance of the tree which is grounded at the trunk. 
The conductive nature of the tree makes it a large receiving antenna and any 
contact with the tree forms a voltage divider.  I have made the measurements 
to conclude this is the approx resistance value, and as far as I know, no 
one else has done this.This resistance plays an important role in the 
capacity coupling to the upper portion of a LF vertical. Just a few pf of 
coupling to 10k amounts to a large loss in Q.

If you are ever in the Boston area, and have a few hours, I'd like to have 
the opportunity to  demonstrate these effects - even the amplifierless tree 
antanna which continues to be my main receiving antenna.

Bill A

>From: "Peter Barick" <[email protected]>
>Reply-To: [email protected]
>To: <[email protected]>
>Subject: Re: [Lowfer] Embattled E-Probe
>Date: Tue, 07 Oct 2003 12:14:57 -0500
>
> >>> [email protected] 10/06/03 10:11PM >>>
>You know Peter, you ought to get outside and run some of these
>experiments,
>yourself, instead of sitting around and making fun of those that have!
> >>>
>
>Sir Bill, thanks for the comedic credit, though I'll pass on that
>appellation for now. Interesting, you minding my time/endeavors but
>let's stay on topic. You didn't answer the essential part of last post
>and it pertains to your assertions, perhaps you forgot. So here goes
>again:
>
>" Why is cap-loading bad (when under trees, objects (first floor of a
>1,000 foot hotel),
>  but cap "sapping" is OK?"  Here, the hard part may be "sapping" and
>take it as a
>  pseudonym for your words below of "spacing became 0 [zero]."
>
>Bill, there seems to be a contradiction here. It's as if we can have
>cake and eat it too. Can that be clarified for the list, esp. newbies?
>
>
>Bill says: " If you had ever walked around with a potable LF receiver
>in one hand
>  and an E-probe in the other you wouldn't be making these statements.
>"
>
>Me: Correct, w.r.t LF. There is ample info to attest to the "electronic
>umbrella" thesis. Further, I shall not be mounting a probe in my Catalpa
>or one lonely pine when I have a tall tower for that purpose. Guess it's
>a matter of taste and best use of my time/resources. Plus, I believe a
>probe works best consistently, *all the time* in a clear environment,
>ie, in a traditional milieu.
>
>Bill says: "Those that have touched an E-probe to any tree know exactly
>what I mean."
>
>Me: OK, I haven't. But the issue isn't only raising sig levels
>absolutely. If noise rises proportionally this is no useful gain. So,
>what have you found about noise, if there was a test for that? Are you
>saying there was a net gain over noise, hence a real benefit?
>
>Peter
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