[Lowfer] Tree Experience

[Michael Sapp]

Kurt:  Well, I have not tried the nail in the tree coupling method, but I 
have an old Sony ICF-2001 that essentially uses a 4ft whip e-probe front end 
(along with an always connected ferrite loop) and goes down to 150 kHz. 
Tuning in an NDB station and then walking over to a tree slowly bringing the 
radio and antenna within several inches of the tree trunk often increases 
the signal strength of a received NDB. Generally, the higher I hold the 
radio near a tree trunk, the more signal is coupled. At the base of a tree 
trunk not much improvement is noted, but several feet up a trunk the 
improvement is noticeable by ear. Perhaps 10db guesstamate at times.  So the 
thought-balloon of a tree being a large RLC circuit presents itself.

    I built one of W1VD's J310 e-probes last summer and did a walk about and 
noticed some trees coupled signals better than others with an FT-817 as the 
receiver.  I live 4.5 miles from a 50KW AM station (KDKA 1020) and Jay 
suggested listening to the second harmonic at 2040 and comparing fundemental 
and 2nd harmonic signal levels (that gives a relative indication of 2OIP 
performance). I have a good collection of attenuators, so it was possible to 
make a reasonable measurement--- mid to high 70's I recall as best 
obtainable.  Interesting observation was I was able to find certain 
locations in and around my yard away from trees while the 2OIP improved 
significantly (i.e. minimum 2040 harmonic signal level observed).

Keep in mind that e-probes tend to couple to anything nearby, and that 
capacitive de-tuning may have been responsible for the diminishing 2OIP 
performance of the e-probe and FT-817 combination as the portable 
combination was moved closer to a tree or trees.  (Interesting also this 
effect is not observed on telephone poles---dry wood).   The Sony ICF-2001 
acts similarly.

At this point one other thought crossed my mind. Is the reduced 2OIP 
performance observation due solely to capacitive loading of the e-probe to 
the nearby trees, or is the relatively strong signal from the 50KW station 
also creating some level of   "ionic"   non-linear conductivity process 
within in the tree(s)---which then a portion thereof is re-radiated or 
otherwise coupled to the e-probe?  I don't really have an answer to that 
question, but perhaps it is something to contemplate....(1:the nature of 
ionic RF conduction in liquids vs free electron RF conduction in metals, 2: 
possible effect of local environment on e-probe gate bias resistor value 
selection for performance optimization ).

73  Mike wa3tts







----- Original Message ----- 
From: "KD7JYK DM09" <kd7jyk at earthlink.net>
To: "Discussion of the Lowfer (US, European, &amp; UK) and MedFer bands" 
<lowfer at mailman.qth.net>
Sent: Thursday, December 26, 2013 11:27 PM
Subject: Re: [Lowfer] VLF


> "If anyone has any " I tried that " experience with driving a nail into a
> tree, and
> connecting a wire to it for receive; I would like to read about your
> experience with it.."
>
> Was it on this group there was extensive discussion about that, or another
> group?  One fellow has done it for years, even mentioned "hiss" that 
> varied
> with temperature or time of year.
>
> Kurt
>
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