[TowerTalk] (no subject)

[K7GCO@aol.com]

In a message dated 9/19/00 5:57:25 PM Pacific Daylight Time, 
depagnier@uswest.net writes:

<< 
 K7GCO@aol.com wrote:
 
 >   Hi-Q trap circuits has it's applications but in antenna traps I'd like 
to see
 > some data
 > to really support it.  Lo-Q traps work just fine.  Data on Hi-Q traps seems
 > to be just "academic."  No one seems to be using them in antennas worth
 > observable benefits.    K7GCO
 >
 
 I am no expert in this field but by definition, low Q means high loss. Q is 
the
 ratio of reactance to resistance in a parallel RLC network. A trap is 
essentially
 a parallel RLC network. While low Q traps are better behaved and less 
finincky
 than high Q traps, they are lossy and thus rob gain from the antenna. While I
 have no data to back this up, I'll bet a dollar to a donut that if pattern 
tests
 are run on an antenna with high Q traps and the same antenna with low Q 
traps,
 the high Q traps will result in higher gain (no brainer).
 
 73
 Dave
  >>
  
No one has proved it yet and no manufacturer has really Hi-Q traps.  The 
first requirement of a trap is to isolate and establish a resonant length of 
conductor which a low SWR can be established on the feedline.  When that is 
obtained and various other positive indications, one tends to think there is 
little left to accomplish.  In the patterns in Eznec I developed just with 
the lowest Q trap of high inductance (that leaked) I didn't see any visible 
change in the dipole pattern.  I didn't measure and compare exactly but just 
for the hell of it I will.  However, for a dipole on 160-40, gain is the last 
thing I'm worrying about.  If it bothers you, make a test set up and you find 
out for sure in yagi's also and you won't lose a dollar or a donut.  That's a 
"no brainer" also.  Since you brought it up and made the bet, the 
responsibility to provide the data is in your lap now.  I eliminate loss when 
I know it hurts me and that is why I use no trapped elements with soldered 
joints.  I have all kinds of data proving the affects of bad joints and very 
few seems to care about that area of loss.  That's a "some kind of another 
brainer."  Joint reactance's inserted into each yagi joint will affect the 
gain, F/B and you can bet every cent you got and the whole bakery on that 
one. With a quad you don't have to worry about that with the one well 
soldered joint.    k7gco

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