[TowerTalk] perspective--Value of a couple dB more in a contest

[K7GCO@aol.com]

<< n a message dated 7/19/00 8:36:24 AM Pacific Daylight Time, K3BU@aol.com 
writes:
  << 8ji@contesting.com writes:
  > I've been racking my brain trying to think of a way to test the theory 
  >  that a few dB of signal makes a big difference in a contest, but I 
  >  can't think of a way to prove or disprove it.
  >  
  >  Can anyone?  
  
  To contester every dB means another (larger) layer of weak ones and 
extending 
  the propagation by more minutes. Also decrease in in/out time in the 
pileups, 
  especially under marginal conditions.
  I will fight for every fraction of dB in gain (and clean pattern) and in 
  eliminating losses, they all add up to few more QSOs that are needed to win 
  the contest.
  
  Yuri, K3BU
   >>
     I agree with W8JI it's a hard test to make as described.   I would agree 
totally with Yuri's views based on all my competitive comparisons during 
contests using side by side antennas of different characteristics of equal 
and different gain.  It really shows when the signals are weak.  Audio 
Processors really show their advanages when signals are weak also.  You are 
fighting intelligibilty cut off.  Inaddition there is another concept not 
mentioned by anyone and is how the dB gain was obtained?  Was it a power 
increase which helps Xmit only?  Was it by going from a 3 to a 6 element beam 
which sharpens both E&H planes.  Sharpening the H plane tends to reduce QSB 
and even lower the angle.  

Or was the gain obtained by stacking 2-3 element beams and obtaining a much 
sharper H plane but the E plane stays the same and covers the same beam 
width.  Yuri used stacked Quads of his design in winning some contests.  
Stacked antennas often do more than their line of sight gain increase.  
 
Does the operator have the ability to instantly switch between the top or 
bottom or both to adjust to the different conditions or distances that vary 
or snag a station that is at a distance other than the favored one of the 
main beam at the time.  With one beam you are restricted to its best area at 
the time.
 
No one has mentioned the difference in F/B created by the way a beam is tuned 
for its gain.  Above average F/B helps cut QRM from the rear covering up the 
weak ones and repeats.  1 dB increase up front can change F/B far more either 
way.
It can mean 6 dB or more on receive either way on QRM from the rear.
 
Further the ability to have a yagi or quad where the polarization's can be 
changed from horizontal, and without tower interference Vertical, 45 degree 
Rt & Lt and Circular CW or CCW all at the same gain can increase receiving 
and transmitting advantages few have ever experienced.  Both antennas and 
techniques exist and can give different angles of radiation with one beam at 
any time.  The Vertical polarization has its max lobe where the Horizontal 
has a null and visa versa.  There is a contestor that will be using part of 
this design in the up coming contests--on salt water.  I'd make every effort 
to have a contest station on salt water as lower vertical beams are killer 
antennas on all frequencies.
 
 How the dB increases are developed and how you slant or twist the 
polarization and/or squeeze or flatten the pattern can drastically change the 
results.  Don't ignore the overall affect of the F/B on your score.  I have 
the ability to switch between max F/B and gain on a quad anywhere in the 
band.  One trick is to transmit with the max gain setting which usually means 
lowered F/B and that tends to keep the frequency clearer for receiving.  But 
on receive the quad switches to max F/B to reduce QRM from the rear.  I know 
it really works in normal band use so it has to be an advantage in contests.  
I have a yagi on a .35 WL boom tuned for absolute max gain of 10.2 dBi with 8 
dB F/B and it tends to clear the frequency--both ways.  It has narrow band 
width but I have a novel way to broaden it.  On 17&12M it wouldn't be 
necessary and is a great antenna for these bands or just phone or CW on the 
other bands.  
 
 Another configuration of signal advantage I've heard no one else use is to 
use the highest gain beam on top (like the above mentioned 3 element) and a 
lower gain beam on the bottom of a stacked array.  I have used a 3 element 
yagi tuned for max F/B using .2R &.15R that gives a great F/B all the way 
around and 8 dBi gain.  Since its H plane is much wider it really fills in 
the higher angle reflection factors normal for the lower height and maximizes 
its total performance when used individually.  There are many times when it 
is the dominant beam on DX.  When both are used the stacked advantage is 
still high and result exceed the line of sight gain increase.  Those with a 
5-6 element beam up fairly high ought to try a 2 element quad, Raibeam or 
Hexbeam 3/4 to 1 WL below the top beam.  Be prepared for some surprises. 
 
 Using 2 vertically polarized yogis on a horizontal boom gives about 3 dB 
gain but some reflection gain is lost over ground--it's a killer antenna on 
salt water.  The vertical pattern is sharper and as is the horizontal pattern 
due to the horizontal spacing.  But over ground the angle is still lower and 
even at LESS gain it can be the better antenna on DX I've found.  It's one of 
the best I ever had on 10M.    
 
 Instead of "splitting dB's" lets use innovative techniques that maximizes 
and massages our RF in a way that adjusts to the variables of propagation and 
interference at all times.  There is no arguement on the advantages of these 
concepts even at the same gain when you use them.  It can also be helpful to 
clean the element joints before a contest.  One ham found his yagi joints 
were even creating noise which went away after a clean job.  Clean the coax 
connector also.  Use the K7GCO hand heat tests.  Run a KW or so carrier for 
5-10 minutes and then feel the DE joints--and the coax connectors and coax.  
If it's warm it's either too small or needs cleaning.  K7GCO 
 

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