Topband: Tophat? Does it have to be at the top?

[Joe Subich, K4IK]

> How does the "hat" on a Cushcraft 402-CD work? You have those 
> crossed aluminum rods after the coil, then extended aluminum 
> after that. What happens if you take off the crossed rods?

The "hat" on the Cushcraft 402-CD (and XM-402) provides relatively 
little capacitance compared to the element tip.  Without the 
"hats," the element tip would need to be extended by 24 to 36" 
each side (and 5' of 1/2" tubing is already a bit mechanically 
suspect).  However, if one were to remove the hats and extend 
the element tips, loses would decrease by about .4 dB (according 
to AO).  

I suspect the hats were there to reach a particular design 
goal for element length and allow smaller tubing in much of 
the elements. 

73, 

   ... Joe, K4IK