[TowerTalk] Necessity of Lo-Q Trap Loss?

[K7GCO@aol.com]

Loss in so called "Lo-Q Traps" is not universal.  Changing the L/C ratio of 
trap and the wires size are factors.  In regular traps I use heavy wire and 
if it DOESN'T HEAT I consider it low loss even if a Lo-Q L/C ratio.  I use 
"inductance only type traps", the wire size that DOESN'T HEAT and I consider 
that low loss.  I have certain designs that leak RF through them some but 
they still establish a 1/2 WL:of length and the proper SWR curve which is the 
most important goal.  They leaked because it didn't establish enough 
impedance to stop all the RF and it had nothing to do with the RF resistance 
of the wire. The reason I used a "leaker trap" was I reduced the inductance 
of it to increase the wire end stub length that resonates it on the next 
lower band (75M) and to give more bandwidth there.  It reduced the bandwidth 
on 40M and so I did a bandwidth balancing act.  The 40M dipole had to be 
increased in length to 80' also to still resonate at 7.2 MHz.  Does anyone 
want to venture an opinion why that was so?  There is a reason.  

This gave a 75/40M no Xc trapped dipole about 92' long with about as Lo-Q 
trap one can make that didn't heat and it deviated from "conventional 
wisdom"--on purpose.  This design will be written up for one of the mags.  
All kinds of innovations can be created not getting stuck in the "usual 
design ruts".  I'm still looking (2nd call) to see any data that clearly 
shows any worthwhile advantage of Hy-Q traps in a dipole or beam.  If there 
is some measurable difference, is it worth the cost and bandwidth loss, 
maintenance, weight and "free space environment" needed to keep it going?  
I've had Hi-Q coils in dipoles and they were sensitive to surrounding 
objects--even verticals.  I rest my case and am open for bets.  I'll open it 
when I see the data and I would like to.  I seldom compromise on performance 
concepts but this is where all my test data led me.  I have a "very practical 
aspect" to my antenna design philosophy.  One has to be able to build it.  
K7GCO

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