Hello Dick,
my 136 kHz antenna (in the period 1997-2001) was completely surrounded
by trees and actually I use 4 of this green lossy capacitors to
support the antenna.
My experiences:
1. Loss is very high. I never got it below 130 Ohm in winter and 160
Ohm in summer.
2. Keep the wires as far as possible from the greenery.
3. An elevated loading coil works miracles. Putting about 50% of the
needed inductance at the top of the vertical wire improved my ERP by 6
dB. More than 50 % would be even better, but that was to heavy in my
case.
4. Even with an elevated loading coil measured ERP was at least 5 dB
below the theoretical value.
5. Due to the losses the antenna Q is that low that re-tuning within a
1 kHz range is not required (at least one advantage).
6. Due to friction nylon ropes do not last very long in a tree. I used
steel cables at the friction points.
7. The combination of wind and Murphy's law will make the trees that
support the antenna always moving in opposite directions. Even with
moderate wind 3 mm flexible Cu-wire easily snaps at 15 meter height
(when it is streched 1-2 meter). An easy and cheap cure is to include
so-called "bicycle strechers" (the rubber things used to fix something
at the rear of a bicycle) in the supporting ropes.
8. The easiest way to get wires 15-20 meter up in a tree is a
slingshot or bow/arrow (the later is more accurate).
To end with a positive note: all the above didn't stop me from working
almost all stations that were active at that time. Best DX was OH1TN
(+/- 1700 km) in normal CW. My DFCW30 signal was captured in the US at
least once but I cannot remind when and by who.
73, Rik ON7YD
Quoting Dick <[email protected]>:
I think this question has been around a while ago, but can't
remember exactly.
What about running an toploaded vertical in the middle of an wood?
It will be a 12m vertical wire, with an flat, pancake shaped coil on
top, and additional at least 4 toploading wires
each 20m long, supported by trees.......
So, nearest tree will be over 25m away from antenna.
What about negative influence (attentuation) caused by the trees?
I'm asking this because it might be rather difficult to find a free
place for the antenna in LX.
(We will be QRV 136kHz upto 10m, so lot of antennas, masts around ,hi)
Dick, pa4vhf
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