[TowerTalk] B.C. antenna

[K7GCO@aol.com]

 In a message dated 8/8/00 4:39:28 AM Pacific Daylight Time, 
w8ji@contesting.com writes:
 << 
  > Take a LW and stretch it out and loop the other end several turns around
  > the radio in the same direction as the loop (try the other way also).  Add
  > a series BC variable to the ground of the radio or back on it self.  Some
  > combo of this will couple in some RF that you will notice.  Or better yet
  > try this.
  
  I think you are saying try winding in parallel with the internal loop 
  and try winding at right angles, but I want to be sure. 
  
 ******This is quite obvious.  Why is there any question?  In some radios you 
can't tell from the outside which way the loop is oriented so I suggest 
another plan if it doesn't work.  I assumed it was oriented the long way one 
time and it wasn't.  I tried winding the wire the other way and it coupled 
strongly.  I really didn't care which way it was--just that it coupled.  The 
technical problem was solved and no justification was required to anyone at 
the time.
 
  Reversing the winding direction (CCW vs CW) of a separate 
  winding, with all things remaining equal, does not change the 
  mutual coupling. If you don't have enough coupling, you need to 
  change the location or axis direction of the winding, or number of 
  turns.
 
 ******This wasn't a problem until you brought it up and you were the only 
one to do so.
   
  >  Run the so called LW just to a ground and do the same thing.  The ground
  > side of the 110 line works great.  Find the grounded wire first of a 2
  > wire line with a neon lamp.  Use the 3rd in-between wire of a 3 wire
  > line.  You will find out how good a ground connection is for a BC-AM 
antenna
     when properly tuned with a 1000 uufd variable.  They try it on
  > 160M then be prepared for another surprise.  Hook it to an oil tank for a
  > great high surface area ground.  It works great on Xmit also.  K7GCO
  
  I think using the leads in a power line, no matter how you check 
  them, as a sole ground is very bad advice.  You are depending on 
  the integrity of not only the internal house wiring but the grounding 
  outside the house for your very life.
  
  There are a number of cases where a single connection failure 
  somewhere in wiring could result in full line voltage appearing on 
  the antenna.
 
 *******I didn't use bare wire, I'm fully aware of the possibilty of open 
ground, I've built and used power supplies up to 10,000 volts taking all the 
proper precautions.  110 volts AC we all have all around us and I'm 
absolutely and positively guilty of perhaps not respecting it to your 
standards.
  
  Not only that, the power lines are almost always a major source of 
  noise and interference. Computers, light dimmers, and arcs and 
  sparks on insulators and in motors all use the power lines as an 
  antenna. 
  
 *******Yes I'm totally aware of it, have never had a noisy line but those 
who have never tried it all warn me of it--repeatedly.  I don't expect any 
noise on the 110 V AC at my new QTH as the power lines are buried and I'm 40 
miles from a big city.  I even talked to the Power Company about it.  They 
say the insulators stay clean but when they do go bad they go bad fast and 
they get fixed fast.  I'll ba able to walk over the buried lines with my 
radio to find a bad insulator.  It will be equivalent to a long buried 
antenna and pick up a lot of "Stealth, Safe and Silent Ground Wave."  I 
should work real well on LSB therefore be ideal for 160, 80 & 40M.  I believe 
AntenneX had something on Buried Antennas.
 
  While there may be cases where a power line lead is quiet and 
  doesn't hurt S/N ratio, I can't think of any case where it is safe as a 
  ground. The safety ground is probably acceptable, if you are sure of 
  the integrity of the grounding system at the service entrance...but 
  even then I'd use multiple grounds or isolate the connection through 
  an AC rated capacitor, like a .01 uF 250 VAC disk.
 
 *******I've described this concept in an article, many other places, twice 
in TT and in each case I suggested a .1 ufd 600V (your 250 V rating is much 
too low for safety and the .l ufd I suggest gives the variable slightly more 
range) capacitor in series with the BC variable capacitor also just as a 
safety factor.  I did fail to mention it this time--but never again to be 
sure.  A potential 110 VAC does seem a bit high compared to transistor 
voltages.  Mean while back to my new linear amplifier HV PS.  Actually I have 
a private line right to Grand Coulee Damn.  No step down transformer needed.  
I connect it right to the final tubes.  I held the key down too long one time 
and burned out a field coil there.
   
  I think the safest approach, and one that would offer the least 
  noise, is a separate ground for the antenna. Otherwise you'd better 
  use an outlet with a GFI breaker, before connecting an antenna to 
  any of the wires.
 
 *******I very clearly suggested connecting to an oil tank outside as a 
separate ground in the post.  I suggested this in greater detail in another 
TT post where I also suggested burying old oil tanks at multiple distances of 
136' for a smooth signal with the Beverage type wire say 10' off the ground.  
This is a new concept of a "Grounded Beverage" as it reflects back the ground 
impedance what ever it is and is often around 50 ohms depending on how many 
ground rods and or radials on the other end use for termination.  No step up 
transformers are needed and a Lo-Z is reflected back at the feedpoint--on all 
bands making it a great listening antenna.  I first used this back in 1936 
cut for 3 MHz initially and which provided the proper harmonic multiples for 
all the BC SW stations.  The BC AM & SW stations just poured in even 
requiring detuning the BC variable at times.  We have been mislead to believe 
that we must use an insulator at the end of an antenna.  Would you believe 
that was started by a glass company that makes insulators?  I read in an 
April 1935 QST that coal smoke used to literally short out insulators and 
required regular cleaning. It destroyed stranded copper wire also. 
 
 Chip of Yasue described at a convention the best 160M antenna he observed 
anyone use.  He checked it out and couldn't believe the signals down under it 
heard.  It was a wire from a short tower fed from a remote tuner on a cliff 
running out into the salt water at some angle.  It's was essentially grounded 
in the salt water.  It is basically equivalent to the land version that I 
have been describing for some time and I even transmit on it.  I have a river 
going by my place in SD and will terminate it in the river and the high 
conductivity mud at the bottom.  When I tell them "their signal is down in 
the Mud but you are Q5," it may take some explanation.  Would you believe 
there are high LF signal levels under ground that need "RF Mining."  
 
 Every time I give a short post on a great idea assuming some reasonable 
ability of the reader, I have to expand on it which I am happy to safely do.  
One 160M contester asked me not to describe this antenna.  He found it very 
useful. Perhaps Tom can be the "Official Ground Inspector" for Ham Radio.  I 
hope I have covered all the safety issues.  Remember every time you turn the 
lights on your hand is an inch away from a 110V connection and an arc when 
you turn it off.  Watch out for buried power lines when driving ground rods 
into the ground.   K7GCO
  
  73, Tom W8JI
 > w8ji@contesting.com
 

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