[TowerTalk] Lossy Traps (long)

[jimlux]

Tom-W3FRG wrote:
> I used a Fluke 80T-150U temperature probe, connected to a Fluke handheld
> DVM to measure temperature. All measurements are in degrees Fahrenheit.
> During the experiments, I measured temperature at three locations -
> the strap connected to the 10 meter capacitor on the front driven
> element; the boom, just behind the front driven element; and the PL-259
> connecting the feedline to the supplied KLM balun.
> 
> [lengthy measurement details and data omitted; conclusions of measurements
> follow]
> 
> 
> It would be most interesting to have access to this measurement detail to
> see how the ambient temperatures were handled during the measurement
> sequence. With the antenna only 30" off the blacktop driveway, and the sun
> at mid day (?), I'd expect some corrections to be in order ?? Or was the
> antenna shaded from direct sun ??
> Probably one method would have been to have T/Cs hard mounted and
> electronically scaned during the testing sequence, eliminating to a degree,
> any outside temperature influence (sun), and pre and post temps could be
> monitored and accounted for.
> 
> Tom W3FRG

There's a whole lot that *could* be done, but I think the real question 
is whether Tony's data can provide a "bound" for the losses, and I think 
that his measurement technique probably does that adequately.  After 
all, there have been assertions of "you lose half your power in the 
trap", and Tony's data shows unambiguously that this is NOT the case. 
Once we get down into the area where we worry about is it 1% or 2% of 
the power, I think you're at a point where other factors are more 
important when it comes to antenna design.  (e.g. I haven't seen many 
ham antennas with rigid structures to hold the elements in place.. heck, 
the vast majority of beams that I see driving to work have elements that 
aren't even in the same plane.. and I doubt the owner is making 
experiments with elliptical polarization)