DX Engineering Maxi-CoreŽ 20 Baluns and Feedline Chokes DXE-MC20-V4-1 TESTS.

[ThaDood]

I did a spectrum test on that 4:1 DX ENG 5kW Balun.    https://www.dxengineering.com/parts/dxe-mc20-v4-1  I did a DC GND continuity test and measured 1.6 Ohms. Not bad, but I did look inside, and I didn't really like how they 1/2 soldered the connections inside, so I silver soldered them with the 140W gun. Passed DC GND tests at just .6 Ohms. Then, I took two 100 Ohm, 1/2W, resisters, (For 200 Ohms.), and tied them to the Dipole bolts. Then used my MFJ-269Pro ANT Analyzer and spanned from 1740kHz to 180MHz. WOW!!!! Solid, flat, 1:1 VSWR from MW to around 27MHz, but 11M and 10M were still a 1.1:1 match. Then, curved to 1.2:1 about 63MHz, and was still that all the way to 2M, which was a 1.3:1! Then, the curve raised about 1.5:1 around 158MHz. Damn!!!!! Now that's wide banded! Anyone ever put one of these Baluns up on a Dipole, or a Longwire? For over 25 Years, I've used the W2DU 4:1 Current Choke Balun, running barefoot power, with nice results. However, I believe that the power rating of that is 300W. The 5kW rating on the new Balun is certainly overkill, but at least 500W won't be a problem.

[redhat]

You can get the same thing for less money from Balun Designs https://www.balundesigns.com/4/  I've used their 1:1 feedline chokes on all my verticals and dipoles, which solved most of my RFI issues.  DX Engineering makes good stuff, but it tends to be expensive for what it is.  Their sales staff also leaves something to be desired.

+-RH

[Brian]

You can roll your own for less than 30 bucks.  1.6 Ohms resistance was poor. 0.5 or so would be what I would expect, even on a 150 feet coax run. I'm guessing the toroid is about 2 and a quarter inches. If so, that's what I use and I've run  about 3 KW PEP without any issues.

[ThaDood]

Yeah... I know... I could've rolled-my-own, and usually I do. But, I had a $20.00 coupon with DX Expensive-neering, so this was a nice chance to use it, and I had only one more week left to do so. I also went with their experience in the toroid core type and turn windings. I'm really not that experienced upon determining core type make-ups and have only wound toroids a few times. The 1st time was with Fearless Fred's help upon homebrewing a MW 7 Element Chebychev LPF. That was over 25 years ago, and I still have that, which has three self-wound toroid transformers. Anyway... I went the lazy way, but am still glad that I've looked inside that Balun.  Maybe, I've bought one that was built on a Friday? Hmmmmmmm???