[TowerTalk] Shunt Fed tower question

[TexasRF at aol.com]

Hello Dick, your numbers are telling you that the feed point is already  
inductive. A series capacitance of 344 ohms should cancel the inductance and  
result in a very low vswr at the frequency of your test.
 
That comes out to be about 250 pF. The voltage rating will be related to  
the rf power used. At 1500w, there will be 5.4 amps through the capacitor and 
 that would produce an rf voltage of 1865 volts rms. Peak voltage will be 
about  2650 so a well rated capacitor would be needed. If made adjustable, 
the voltage  will go well above that number while tuning.
 
Sounds like a nice antenna!
 
73,
Gerald K5GW
 
 
 
 
 
In a message dated 1/17/2012 5:35:09 P.M. Central Standard Time,  
RLVZ at aol.com writes:

Hi  Guys,

I'm shunt feeding a 90' aluminum tower for   160-meters.  .

I found the 50 ohm tap point on the tower and have  the shunt wire  
connected to the tower at that point.   At  the base of the Shunt  wire I'm 
measuring 
the following:

-Rs =  51 ohms.

-Xs = 344.

-Q = 6

-Ls = 30.1 uH.

Please  advise what I need to add to this circuit... such as: a 30uH   
inductor?  If a 30uH inductor can I easily make one, such as: X turns  of  
#10 wire 
with a 3"  diameter?

Thanks,

Dick
_______________________________________________



_______________________________________________
TowerTalk  mailing  list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk