What is the best tuner for..............

[IW5DWU]

Hi folks, I have a question for you experts ..... what is the best solution tuning to Delta Loop antenna with apex at the top and a perimeter of 20 meters ?
He is currently working well for the band of 20 meters but I would be able to tuning for other bands ..... of course I am aware of the limitations of performance
Would be interesting models MFJ-927, CG-3000 SG-237/239.....any suggestions for me?

Here http://www.sgcworld.com/Publications/Books/stealthbook.pdf , they suggest a vertical polarization using the tuner in the apex down of the loop while in other cases suggest you to place the tuner on the center of the bottom of the loop.......

http://www.sgcworld.com/Publications/Articles/237qst0502.pdf

Thanks in advance,

Massimo IW5DWU

[WB6BYU]

The answer depends on how you feed it, and what bands you want to use it on.

A 20m loop will have an impedance around 200 ohms on 10m.  In that case, using a 4 : 1 balun should
give a reasonably low SWR on both bands.

With a tuner mounted at the feedpoint, the only problem might be where the loop is 3/2 wavelengths
long, as that will be a high impedance point.  Fortunately that would be at a wavelength of 13.3m, so
the impedance probably won't be too extreme on either 15m or 12m.

If you use a feedline between the tuner and the loop then you have to account for the impedance
transformation along that line - the wrong line length can give you a high impedance on some bands.
But using 300 - 400 ohm line shouldn't get you into too much trouble - in the worst case you might
have to add or subtract a few feet to get an impedance that you can match on every band.
(At least for 20m though 10m, and probably 30m, but 40m will be more difficult.)

So I don't think it makes a lot of difference what tuner you use.  Just about any normal tuner should
do the job.

The impedance is basically the same regardless of where in the loop you feed it.  There will be a
difference in radiation pattern due to the shift in polarization, and you can experiment to see which
works best in your situation.

[N2LK]

I am currently using a 20 meter delta loop antenna fed in one lower corner with 3oo ohm twinlead. Antenna is apex up at 24 ft, lower horizontal section 8 feet off the ground. Best I can do with my small yard.

I chose a 32 ft. length of twinlead to my shack, then a 4:1 current balun. My rigs internal tuner has no problem tuning it 10-20 meters with good success.

My external auto tuner from LDG tunes is also on 30 and 40 meters. Noise levels are significantly reduced on those lower bands. In many cases I can hear stations on 40 meters with the loop and not on my resonant 40 meter vertical due to the noise pickup.

Its a decent multiband option. I may place the LDG tuner in a outdoor enclosure and mount it on the tree for the fun of it and see if that helps it a bit more.

Have fun!

[IW5DWU]

Thank you guys.....do you think between AutoTuner and antenna is better 4:1 balun or it's the same ?
SGC suggest horizontal polarization, i will try both situations

[WB6BYU]

With the autotuner at the antenna feedpoint, I would not use a 4 : 1 balun unless you have trouble
matching the antenna on some bands.

Whether vertical or horizontal polarization works better depends on the height above ground and
your local ground conditions.  Generally I expect horizontal polarization to work best unless the
antenna is close to the ground.  If you feed at the bottom center, the top of the loop will always
be a point of maximum current.

[WX7G]

For vertical polarization on 20 meters feed the loop 1/12 wavelength from a bottom corner.

[K2ZS]

I would stick with the SGC antenna couplers. I have the SGC-230 and it works for my indoor antenna situations.

Keep looking through some of their publications. I learned that they recommend using a loop that consists of 80' (24.3 meters) of wire for a versatile all band antenna.

[AE6ZW]

I have used both manual type  with Coil and 2 Variable capacitor, and automatic type with relays , capacitors , and coils.  I sold my automatic one , replaced with Manual one, I think manual one work better for my usage , which is to tune random wire antenna.