[CQ-Contest] Coax Stubs for SO2R

[Steve NR4M]

Jim,

Been following this thread since it started (this time) several days 
ago.  I have lots of interest in it as I have a multi multi station here 
in VA.
I have built coaxial stubs in the past using my AIM 4170, FSJ4 heliax, 
and K2TR's data as a good place to start.  I think after screwing with 
them for years, I've gotten pretty good at putting the nulls where I 
want them.  And, they seem to work, but no real data on how well they 
work.  My 40m 3rd harmonic on 15 is about S-5 and I can get withing a 
couple of KC, or so.  It's just not much of a problem any longer.

Been quite interested in your suggestions on how to place them for 
maximum attenuation of the undesired RF.  I, like many, I guess, have 
installed them at the output of the amplifier, because that would be a 
50 ohm point in a properly tuned amp.  But, now I see that it's more 
important to know what the impedance of the harmonics is on your band of 
choice.

What got me up and moving on this is your comment in a previous post 
today about it being the second harmonic that's important.  I have been 
building stubs, per N2TR, that covered multiple bands, without really 
focusing on a particular stations 2nd harmonic.

I pulled the coax off the stub set on the back of my 20 meter amp, 
connected a Rig Exper AA54, and started looking up my coax toward the 
antenna.
On 10 meters, I saw R101 -J14.6 and on 15 (for the heck of it) I saw 
R112 j-36.

Following your instructions in your pdf on locating the stubs, I am just 
about where I need to be.  If I added .44 feet of Coax, it would be 
right on the voltage peak.

Do these numbers above look as they should?  I was expecting higher R.
-- 

73 de Steve, NR4M