Description
1 – 54 MHz ATU Choke BalUn with bifilar windings for optimal symmetry
This ATU Choke BalUn 800 Watt provides optimum symmetry in the feed line. The BalUn is designed to be used in conjunction with an antenna tuner. If an Asymmetrical antenna tuner is used to feed a symmetrical feed line (and antenna), a BalUn is required. BalUn stands for Ballanced – Unballanced. This allows us to connect an unbalanced system (coaxial cable) to a balanced antenna system (e.g., dipole antenna). The ATU Choke BalUn 800 Watt is suitable for QRO use.
Operation
The main reason to use a Choke BalUn is to ensure that currents in the feed line are of equal magnitude and flow in opposite directions. As a result, the feed line does not become part of the antenna and therefore will not radiate. This results in all sorts of unpleasant effects, such as: interference, disturbed radiation pattern of the antenna and noisy reception.
A ferrite toroid is used to enforce symmetry in the feed line. There is a lot of information on the Internet and even in literature about making a BalUn, but unfortunately there are also a lot of bad designs that hardly work. This design is one that has proven to work very good!
Use this design only in conjunction with an antenna tuner! This BalUn can handle a relatively wide range in terms of impedance, so it is not a 1:1 BalUn specifically for 50 Ohms.
This kit includes:
- IP65 enclosure 100 x 100 x 55 mm
- Toroid Amidon FT240-43
- Winding wire 18 AWG – 2x 150cm PTFE 19 x 0.25 mm copper “Silver plated”
- Toroid mounting plate
- Stainless steel M3 6mm screws 4x
- Stainless steel M3 Spring washer 4x
- 2x Banana plug connection
- 1x PL 259 chassis socket
- 1x M3 cable lug
- 4x stainless steel M3 Bolt 12mm
- 4x Stainless Steel M3 Nut
- 4x Stainless steel M3 washer
- 4x stainless steel M3 toothed washer
Click here for a detailed construction description of the ATU choke BalUn
Tips:
- Place the ATU choke BalUn as close to the antenna tuner as possible.
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