Preliminary Balun Analysis

BALUN B0  (No Balun)

The wire legs were connected directly to an SO-239 with 2cm pigtails.

The coax consisted of 115 ft. of LMR-240 plus 3.3 ft. of Aircel-7. This is exactly one half wavelength on 3.480 MHz (close to resonance of the wires).

All tests beginning with B2 use  brand new RG-58, 1/2 wavelength long.

DOWNLOAD DATA FILES:

BALUN  B1  (1:1 W1JR Guanella Balun)

The same wire legs as used above were connected to a B1 and the same suite of tests were run again.

The coax consisted of 115 ft. of LMR-240 plus 3.3 ft. of Aircel-7. This is exactly one half wavelength on 3.480 MHz (close to resonance of the wires).

All tests beginning with B2 use brand new RG-58, 1/2 wavelength long.

DOWNLOAD DATA FILES:

B2:  1:1 Guanella (W1JR) Choke Balun

This choke balun consists of :

• 1.40m (4'7") of special Teflon-like Coax (DXW142), similar to RG-142
• with 17 turns cross-wound (W1JR)
• onto an Amidon FT-240-31 toroid core.
• 2x PL-259  with gold-plated contacts and Teflon insulation.

DXW142 FEP/TPE-U coax cable 50 Ω

Specifications:
Inner conductor material : solid copper, tinned
Inner conductor diameter: 0.98 mm
Dielectric: FEP, 3.02 mm

One half wavelength (on 80m) of RG-58 coax was used for this and all further preliminary tests.

DOWNLOAD DATA FILES:

B3:  Balun Designs Model 4115t (modified)

• This is the standard Model 4115t balun with top mounted connection bolts.

• I have added two bolts, one on each side, to be used for strain relief purposes.

• The bolts do not connect to anything inside the balun.

• The modifications were strictly mechanical and have nothing at all to do with the electrical characteristics of the balun.

One half wavelength (on 80m) of coax was used for this tests.

Balun SWR Performance Curve across the HF Spectrum:

Balun B4 (4:1 Hybrid Balun)

This Balun consists of a 4:1 Ruthroff Balun preceded by a 1:1 Guanella Balun.

The 1:1 Guanella Balun is the same Balun as used in "B1" above.

The 4:1 Ruthroff is wound on an FT-240-61 Core.

In this case, the Ruthroff is just a transformer and the Guanella performs the duty of the balun.  Neither alone is sufficient on its own to both match and impede Common Mode Current.

One half wavelength (on 80m) of coax was used for these tests.

BALUN PERFORMANCE CURVES:

B5:  4:1 Dual-Core Guanella

Consisting of 2x Ferroxcube TX 36/23/15-4A11.  These cores are nearly identical to FT-140-43, except these have a thin epoxy coating on the outside surface. Their beginning permeability is 800.

Each toroid is wound with 12 turns of twisted pair, Teflon insulated 0,75 sq. mm wire.  This is in between AWG 18 and AWG 19. 

Its SWR curve across the hf spectrum is as good as any, which negates the "theory" that twisted pair won't work in baluns.  

BALUN PERFORMANCE CURVES:

B6:  Dual-Core 4:1 Guanella Balun

The balun pictured on the right is from my 40m OCFD, but nearly identical to the one used  in these tests on my 80m OCFD.  The 80m OCFD uses 2 additional turns of wire per core.

B6 SWR CURVES:

B8:  Tiny Hybrid Balun

This 2-Core Balun consists of:

• an LDG LBA-4, 4:1 Ruthroff Balun
• a 1:1 Guanella Choke (see below)

Note:  This balun was tested in the very beginning, before I had decided to do this Battle of Baluns test.  This test is not as comprehensive as the tests later outlined for BoB, but the data is of some significance and has been included for the purpose of completeness.

The build quality of this LDG balun is nothing short of pathetic.  The wires inside are only enamel insulated, the device is not 100% waterproof, and the hardware is not even stainless steel.  

I cannot recomend this specific balun, however the measured results of the combination of this balun and the 1:1 Guanells choke look very good.

B8 SWR CURVES:

B9:  Hybrid CBC Balun

Sorry, no further details about this balun technology are available at this time.

B9 SWR Curves:

B10:  HYBRID BALUN

This mini-hybrid balun consists of a 1:1 Guanella balun on the coax side and a 4:1 Ruthroff balun on the antenna side.

B10 SWR Curve: