Ever wonder what's inside those W2DU baluns?

[Captain Kilowatt]

Thanks for the pic!

Hmmm, if it is a "W2DU" balun, I would have expected a string of ferrite beads over Teflon coax as that is the only configuration Walt ever really promoted that I'm aware of. Unadilla also sells "W2AU" baluns that IIRC are the conventional transformer type of blauns.

From what I've seen, "W2DU" baluns encased in PVC are characterized by being much longer than their transformer counterparts.

I have a Van Gordon balun that is on the 40/80 fan dipole we use for Field Day that is of the transformer type that works well.

I just received three of the W2DU balun kits from the Wireman that include fifty #73 beads, a 16" length of RG-303 cable, and a copy of the March 1983 article by Walt describing the choke balun.

For his W2DU "baluns", Maxwell specifically used ferrite beads over RG-303 coax, although you can get the same effect with putting ferrite beads on other types of coax as well.


The DB

I hang my head in shame!! It is NOT a W2DU balun it is a W2AU balun!! Small change of callsign but BIG difference. I stand corrected. The callsign was originally on the housing but has since long worn off and I was sure it was a W2DU however I must stand corrected. As soon as I saw the callsign W2AU it clicked. My apology to the masses.

 

[sunbulls]

In the 60’s and early 70’s I started using the 4:1 W2AU voltage balun on a 80 meter folded dipole with 12” fiberglass spreaders. The SWR was very flat with less than 1.8 on the band edges. No tuner needed. The 4:1 W2AU has been my favorite for that band for years. I can’t say I’ve ever tried a W2DU current balun, but several have told me that Unadilla and other clones have been having quality control problems with both versions. I may build my own balun in the future, but these days I'll most likely go without and use a simple dipole antenna instead.

 

[kopcicle]

Yeah , well...


next

 

[N0NB]

I hang my head in shame!! It is NOT a W2DU balun it is a W2AU balun!! Small change of callsign but BIG difference. I stand corrected. The callsign was originally on the housing but has since long worn off and I was sure it was a W2DU however I must stand corrected. As soon as I saw the callsign W2AU it clicked. My apology to the masses.

Aww, no problem.

I'll bet that Walt contended with the confusion more than once and I suspect that he was quite the gentleman about it. I never met him. He left us a legacy of transmission line matching, tuners, baluns, SWR, and probably more!

For anyone that has access to the QST archive, look up his article on his work with the FCC during WW2. Very interesting stuff.

Speaking of Unadilla, I bought some of their Reyco traps for 10 and 15m some years back. I probably tried to run the poor thing on 17 or 12m and may have cooked one of the traps. I found it the other day when I was looking for something else and am thinking that I ought to figure out where the problem is. I also used a Unadilla W2DU balun with it, unless I smoked that thing.

 

[The DB]

I hang my head in shame!! It is NOT a W2DU balun it is a W2AU balun!! Small change of callsign but BIG difference. I stand corrected. The callsign was originally on the housing but has since long worn off and I was sure it was a W2DU however I must stand corrected. As soon as I saw the callsign W2AU it clicked. My apology to the masses.

No need for shame, it was an honest mistake. I only noticed it because of all the authors I have read I am by far the most familiar with W2DU's work. Its a good foundation for building on if you truly want to understand what is happening with antennas...


The DB

 

[Handy Andy]

So with the day going from one extreme to the other...is that Balun a 1:1 or is it a 4:1?

:+> Andy <+:

 

[Captain Kilowatt]

So with the day going from one extreme to the other...is that Balun a 1:1 or is it a 4:1?

:+> Andy <+:

It is a 1:1 balun.

 

[Handy Andy]

Thank you - I wasn't sure

But whatever happened to

W2BU
and
W2CU

One comes back a Frisbee fanatic site...
The Other Comes back as South Carolina...

Then of course there is the wonderful renditions of word game permutations

 

[HomerBB]

I hang my head in shame!! It is NOT a W2DU balun it is a W2AU balun!! Small change of callsign but BIG difference. I stand corrected. The callsign was originally on the housing but has since long worn off and I was sure it was a W2DU however I must stand corrected. As soon as I saw the callsign W2AU it clicked. My apology to the masses.

Go sit in the corner.