[TowerTalk] add a 3rd el to 40-2cd (now coils)

[John Keating]

I saw the comments about the low Q coils on the 402-CD, and had heard
similar comments about similarly constructed coils, which got me thinking
about the ones on my 2L 40M yagi and wondering (again) how to explain what
I'm measuring and experiencing in terms of performance (which seems pretty
good). The coils are ~13uH (measured with several instruments), constructed
as 39 turns of 12g enameled wire close wound on an 80mm dia 3mm-thick
fiberglass form (form is insulated with heatshrink tubing) with a 2.6:1
length-to-diameter ratio. Coil.exe predicts a Q of about 350 and form loss
of 14%. Hamwaves calculator gave Q values >400. I tried to measure the coils
using a Heathkit QM-1 and it showed Q > 500 which is the limit of the meter.
The antenna is direct-fed (no match) and has a 2:1 SWR bandwidth of 185KHz
and 45 ohm impedance at resonance. The fairly wide bandwidth and near 50 ohm
impedance would seem to indicate losses, which I think would be inconsistent
with the above Q values. Looking for suggestions as to what might be going
on.