inverted V dipole

I'm hacking one, from CPVC, aluminum electric fence line, and .080-inch string trimmer line. Strung from two trees on the ranchito, in a roughly North-South orientation.
The angle of the vee is about 135 degrees.

It's not as high as I'd like, only about 3 feet above the ridgeline of the house, but that makes it easier to reach until it's tuned and I've wound a balun for the feedline.

My MFJ207 says it shows 3-plus-to-1 VSWR at 14.285 MHz, and bottoms out at 1.1:1 or so at 15.75 MHz. The balun goes on next, and a longer permanent feedline, and some more hardware so the CPVC feedpoint comes off without untying trimmer line. Then get that pup about 10 feet higher up, which involves ladder work on the trees.

I'll tune this better to 20-meters by reducing the angle (the guy points for the poles stay where they are, while the feedpoint rises) then later by cutting length off the two poles.

Let's see how this stands up against Wyoming's wind. Twas a bit breezy today and feedpoint was relatively stable.


Chad said...

Getting an auto-tuner? Then you could just use your gutter as an antenna..

TheCabinetMan said...

...then later by cutting length off the two poles.

If your antenna resonates at a higher frequency than your target, the legs are too short, not too long. Add wire, don't cut it. Twist fit is good for testing, then solder when it's the way you wannit.


Fûz said...

TCM, you are right and I am embarrassed. Ouch.
Chad: I do have the autotuner but want the challenge of the inverted V, running 5 W.

TheCabinetMan said...

No sweat, Fuz. I bought one of those 'El Cheapo' 40m dipoles from HRO that claimed it was cut-to-tune. Unh huh... I had to add ~14" of wire to each pole to get it to resonate w/o a tuner at 40m's center freq.

BTW, freq response in nearly all systems is logarithmic, so center freq of 40m -- 7.000 to 7.300 -- is not necessarily 7.150. Easy calc is SQRT(Fhi*Flo). So center freq of 40m is 7.148. (Yawn...) I admit that the difference is negligible in narrow bands. Just FYI.


Fûz said...

Winds are gusting to 50mph here today, and the trimmer line is holding out quite well.