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Wind your own transformers

Discussion on which matching transformers are best suited for Flag and Pennant antennas.
Flag and Pennant Antenna mail list, November, 2000

George Maroti: An option for matching your Flag or Pennant is a Mini-circuits transformer.
I use a Mini-Circuits 16:1 transformer, purchased from Nebraska Surplus Sales.
More info on this product may be found at the
Mini-Circuits web site.

Tom Rauch, W8JI: Mini-Circuits transformers are very easily overloaded and damaged.
They also can't handle any DC bias on the windings.
They are good small signal transformers in controlled environments, but I wouldn't use them on antennas in general applications.
Just wait til you get a little 60 Hz AC voltage across the windings! The Mini-Circuits transformers will cross-modulate the desired signals. On the 4:1 transformers, as little as 20mA current will cause core saturation.
While common mode on the feedlines may not be a problem in all installations, I'd still opt for a much isolation as I could manage. That goes for Beverages as well as terminated loops (and ground return half-loops like the Ewe).
An ounce of prevention is better than missing some DX signal close to noise floor because the system had conducted noise you didn't know about, or because it decreased directivity of the antenna.

I use ABS boxes for almost all of my stuff, because it is easier to keep the shield of the cable isolated from the antenna and/or the antenna's ground.
"Shielding" is not required, and can actually only increase common mode problems, so the only argument for using metal is life and the "warm fuzzy feeling" of a mechanically tougher box.
I'm still using ABS boxes from the 70's.

Earl Cunningham, K6SE: I was aware of the Mini-Circuits 16:1 transformer, but I didn't recommend it mainly because of its tiny size -- even if the windings are not one on top of the other, they can't be widely-separated.
Tony, N2TK mentioned that also they were useless in the strong RF V26B.

George, K0FF: I have a fine 4 x 4 inch box that has a gasketed cover (all plastic), and the binding posts can now be replaced with simple brass screws.
One other point then Earl, is a rope eye still needed?

Earl Cunningham, K6SE: Rope attachment at the feedpoint end of the antenna is necessary for the Delta configuration of the antenna and for the point-fed Pennant and Diamond.
With the Flag and the point-terminated Pennant, the box can be simply taped to the wooden support mast.
The feedpoint end of any of the antenna configurations should be near the support where the box can be secured with short leads to the feedpoint.
A short rope tied from the feedpoint insulator to the support can secure that end of the antenna. This eliminates any strain on the box which would be present if a rope tie on the box was used.
The rope should be attached to both holes in the feedpoint insulator to reduce strain on that item.

Last winter, during our "DXpedition" to a nearby (60 miles) salt lake bed for the CQ WW 160-meter CW contest, we used a Delta receiving antenna. A small plastic refrigerator box housed the transformer, and the rope at the feedpoint corner was tied to a the hole in one end of the feedpoint insulator. The box was taped to the insulator. There were no problems with this arrangement while using the antenna and rotating it. Of course, taping the box to the insulator was only a temporary arrangement and might not hold up for a long period of time.

The beauty of the Delta configuation is that it needs only one 20-foot support and two stakes driven into the ground and can be easily rotated. It lends itself extremely well to portable operation and is becoming popular as a receiving antenna for DXpedition use.
Consideration should be given for the placement of the connections on the box, so that the box can readily be used with any configuration of the antenna (Flag, point-fed Pennant, point-terminated Pennant, Diamond and Delta).

Eric W3DQ: ICE makes a model 185 balun and 180i terminator that they claim is good for pennant and flag antennas.
The 180i has taps up to 800 ohms, not the 900+ ohms that people are suggesting. Likewise the balun taps are different than what I'd have expected, considering that they are saying these devices are for pennants and flags.
When I spoke to ICE, tehy said "don't worry, the difference is only 10 percent" .

Earl, K6SE: The only ones making the correct transformer to my knowledge are K0FF and K1ZV.
The ICE transformers are made primarily for Beverages and are not well-suited for use in Flags and Pennants.
The 180A is a UN -UN design which has isolated windings for primary and secondary BUT they tie the "ground" ends together. There is a lightning discharge suppresser in there as well and a large capacitor in series with the input winding for DC block - this is all for static and lightening suppression.
Since the 300 ohm winding is not needed, just open the box and unsolder the ground connection for the secondary winding. Also unsolder the 300 ohm connection and put the ground connection you lifted onto the 300 ohm terminal. You now have a BAL-UN 450, 600, and 800 ohm winding with isolated windings.
If you don't wish to do this yourself ICE will send a new version to you, the 180I which I think I convinced them to make as a standard product based on what we just learned.
ICE products can be ordered on-line at the official ICE web site Here you will find datasheets as well as free publications on grounding and beverage antennas.
If you have any additional questions, contact Mike Koss at ICE (1-800-423-2666) directly. He is truly interested in the application (for Flags and Pennants).
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