[Elecraft] antenna question

[George, W5YR]

You will probably never notice the difference between 175 ft and 145 ft
except perhaps a bit on the lower bands. The tuner will adjust differently,
but I really doubt that will see much difference in operation.

I would keep the 145 feet rather than cut it to 137 feet (why a resonant
antenna when you are tuning the system anyway?) but if you can droop the
ends down 15 ft, you will still have your 175 feet with neglgible effect on
results. It may tune a little differently, however. Remember that the ends
will be a a relatively high r-f voltage, even with 5 watts, so make sure
that no one can come in contact with them.

I am a firm believer in non-resonant antenna lengths when using ladderline
and a tuner. That way you have smaller variations in feedline input
impedance that you do with resonant flat-tops. Besides, the antenna will
never show a driving-point impedance of 450 ohms resistive on any band, so
the antenna length is highly non-critical from that aspect - just so it
reaches from one tree to the other!   <:}

73/72/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
Icom IC-756PRO #02121  Kachina 505 DSP  #91900556  Icom IC-765 #02437


"David A. Belsley" wrote:
> 
> Well, the ol' K2 has been very happy with my 40 meter extended double zepp
> with a transmatch. It has a flat top of about 175 feet, and it's done
> beautifully 160-10.   But one of the trees it is anchored to is
> disappearing.  My alternative gives me a stretch of roughly 145 feet max,
> probably 142 feet to play it safe.  Of course, half wave for the bottom of
> 80 meters is roughly 137 feet.  My question is, given that I use a
> transmatch anyway, am I better off putting up 137 feet or 142?  I've often
> felt, "get up as much wire as you can."  But being so close to a half wave
> makes me wonder.  Any thoughts?
> 
> thanks,
> 
> dave belsley, w1euy