[TowerTalk] 40m optibeam de-coupling stubs

[Jim Thomson]

The 4 el 40m optibeam  yagi  uses  de-coupling stubs on each ele half..on all 4 x eles.   This is done so the array doesn’t resonate on 15M.
Ok, so where does it resonate then?    It has to resonate somehwere if not on its 3rd harmonic.     The F12  340N resonates around 24 mhz..and will screw up a 12m yagi....
yet the 340n does not use the de-coupling stubs.  

Has anybody with an optibeam  4 el  40m yagi  swept it  with a MFJ-259B  or an xcvr on low power..to see if and where it does resonate.  ( freqs other than 40m obviously) 

Tnx... Jim  VE7RF