[Lowfer] Excellent VLF condx this morning! - pa0rdt in a tree

[Mitch Powell]

Thanks Laurence:
That's very helpful.... it would appear ( based on previous comments about the active antennas ) that
your vertical portion would end at the 15 ft point where you added the 77 toroid "choke".
II think I may try that - as I have a couple of the amrad antennas - and will see if 7 turns is
adequate at these frequencies....as a choke. I have some 20 and 30 foot used telephone poles
that might serve as starting points - and several 50-90 ft spruces and cherry trees.
Now, where did I put the spud gun ?

73

Mitch

 


On 2011-09-18, at 3:11 PM, Laurence KL7UK wrote:

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> I found there was a small improvement at LF/MF and a "larger" one at VLF (Im being vague) hoisting the whole lot thru and above the Pecan tree canopy. The hanging coax is choked down about 15ft down using 7T thru large  77 material (I had to hand) - coax outer is bonded to a number of earth paralleled  Earth rods on the way to the shack. This apartment is RF wise transparent so I still get direct radiation from the house equipment and dont have the ability to bond to a rebar/building reinforcing acting as a Faraday cage.
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> The jpg shows how it worked but it was such a contraction and the gains were so small Ive going back to supporting the probe inside the tree canopy but away from the branches a few feet. Bit less of a target too. Im guessing as the Z of the probe isnt so high as say a portable VLF receiver with say 10Meg Z impedance we are getting less shunting. Certainly walking up the road with such a receiver (marveling at the Hum) tree "dumping" is noticeable within 30 or more feet with the much higher Z unit.
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