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Click for Kinshasa, Democratic Republic of Congo Forecast

Tuesday, August 21, 2007

Ugly balun CDrom box

Ugly balun with CD rom box
All Band HF Air Core 1:1 Choke Balun

For my dipoles 80 and 40m, I use at 9Q1EK station some baluns since October 2006.
But unfortunately one day the ferrite didn't resist.
I have decided to construct a Choke balun according to the N4UJW method.

NOTE de AG6K: Some people build choke-baluns, without a plastic coil-form, by scramble-winding the coax into a coil and taping it together.The problem with scramble-winding is that the first and last turns of the coax may touch each other. This creates two complications. The distributed-capacitance of the balun is increased and the RF-lossy vinyl jacket of the coax is subjected to a high RF-voltage. The single-layer winding on the plastic coil-form construction method solves these problems since it divides the RF-voltage and capacitance evenly across each turn of the balun"....AG6K

Do not let the first and last coils touch!

Here an example in the pictures below using cable ties on PVC box forms which work well.

N4UJW recommande 18 to 21 feet or 5,48m to 6,40m for the coaxial lenght and must be coiled with contiguous ellipses.
This chock balun will be installed at the feet point of the antenna.
The parts to make this kind of chock balun being difficult has find in Kinshasa, I had the idea to use a original kind of support.
A box…empty for sure…., hi… of CDrom.
In the beginning I was septic when about the solidity and about the distortion of this box.
But, I tried ….and here is the result with:
A box of CDrom, two screws with nuts, small discs steel, S0239, large Scotch tape, amalgaming tape and without forgetting the CD blank that will be on the top of it box..
I arrive to ties 5,20m of RG213cable coaxial, therefore sufficient.
The “piton” fixing for the support is screwed in the central core of it box since the top.
don't forget to install a part of large black Scotch tape before coiling.

The pictures do without any comments…!!!

A tye wrip was added to strengthen the all through the “piton” and some holes to the basis for the humidity. For sure, it must be waterproof to the top and the cable.
The total box after construction seems to be solid.
I don't think that it can compete with PVC cases or suitable pipe, notably on longevity in the long time, but it can give a channel of ideas and in my side, is enough for my limited broadcasts duration in 9Q.

More, it resists with the legal power limits…
Good realization if you tempt it. 73 de Georges