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[TowerTalk] Will trees kill me, too? Potato gun

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Subject: [TowerTalk] Will trees kill me, too? Potato gun
From: (
Date: Thu, 5 Jul 2001 11:58:29 EDT
 In a message dated 7/4/01 6:21:14 AM Pacific Daylight Time, writes:
 << Here is another approach to "wires in the tree" that I happened across 
this Field Day.
      I was riding my bicycle on Field Day Sunday morning and I came across 
the North Kitsap Amateur Radio Club gang.
      After introductions and the such, I noticed that their wire antennas 
were way the heck up in some Douglas Firs.
  Like 80-100 feet up. So I asked "How the heck did you get them so far up 
for Field Day?"
            Answer: Potato Gun
  Only took several shots from an experienced cannonier and they were in 
business with some very high wires. Seems like there could be some home 
application here.
  Kim Bottles - K7IM
  Bainbridge Island, WA
   I saw this Potato gun in action and it's impressive.  A fairly heavy 
weight of potato is very well accelerated at a fair velocity.  Having a fair 
knowledge of internal ballistics I would make this suggestion.  I'd wrap the 
combustion chamber with several layers of fiberglass cloth and resin and 
progressively less to about 1 foot from the muzzle.  As is don't stand 
directly behind it. The pressure rise is very fast and that puts great strain 
on the tubing and joints however joined?  The quick squirt of gas in the 
chamber is a bit hard to measure.  Repeated firings will weaken any plastic 
and joints.  Just a suggestion.  As I recall it's made from PVC tubing.  
 Another "Magnum Sling Shot" was shown in CQ Mag.  A 3' 2"x2" is anchored to 
the top of a 6-8' step ladder and surgical tubing is used to a leather pouch 
to launch fairly heavy potatoes weights about as high as you would want to 
go.  The angle of the step ladder is about right also.  I've used sling 
shots, fishing rods and bow and arrows.  The main thing is to get it high 
enough so that it falls to the ground on the other side and that is why the 
"Magnum Version" works so well--one shot if your aim is good.  If it doesn't 
it can get hung up on branches before it hits the ground and it's almost 
impossible to pull it back.  
 One time I joking described gamma Matching a "Silver Maple of Iron Wood 
Tree" by connecting the coax shield to the root system.  Pull down limb about 
10' high and make a "Limb O Match".  Use the limb that gives the best match.  
The branches are not too inductive so no series capacitor is needed.  Some 
limbs are fairly inductive if the SAP reactance level is high.  A perfect 
Limb O match can be made by using certain length of limb but connecting it to 
a capacitor make from the outer bark.  You cut a 1" groove in the bark all 
the way around the tree about a foot apart to isolate it from the rest of the 
tree making a tubular Bark capacitor.  The width of the sleeve determines the 
capacity.  It's location determine the Z match.  Start reducing the width of 
the sleeve to reduce the capacity until 1:1 is obtained.  It's called the 
"Bark O Match.  You might have to practice on a tree or 2.  It makes a great 
broad banded vertical and it's very quite.  Pine trees have the right taper 
for a circular "LOG PERIODIC" for talking to the satellites and Flying 
Saucers.  Their conductivity is on the low side but if you feed it salted 
water for a day it becomes progressively conductive.  The gain increases for 
about a week before it tapers off.  
 Don't laugh--I've seen in Army Training Manuals some of these very 
suggestions.  They even suggested connecting to fence wires which I've 
already done.  On metal fence posts I've bent the metal tab back and added a 
wrap around Delrin insulator and bent the metal tab back to secure it.  I've 
run green insulated wire on the ground on the 3 neighbors property edge under 
a fence and they have mowed right over it.  It blends right in the grass in a 
short period of time.  Its a great listening antenna on the BC band, 160, 
80/75 and even on 40M.  It matches easily with an L Network contrary to those 
who have problems using them and the bandwidth is great.  I've even grounded 
it at the end and it's a "very quite antenna".  Preamps enhance their 
performance on receive and I've even transmitted on them. I will run a side 
by side test on 2 of them with one ungrounded.
 I have a lake in my back yard here and it freezes over for about a week once 
a year.  I ran an insulated wire over the ice and used it was an "Ice 
Beverage."  As the ice melts it fell to the bottom and becomes a "Mudder 
Beverage."  Would you believe it's very obvious it would never work in LSB so 
it didn't work well on 160-40M.  The Ice Beverage works great on both LSB&USB 
and it's a real "cool antenna."  It's a high angle Beverage on USB and a low 
angle Beverage on LSB using the gain of a long wire and "Mud Reflections."  
On CW it was both.  Lake mud is a very high conductivity in particular in SD. 
 That's an absolutely true story, I just made it up.  K7GCO 

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