Complete 1:4 BalUn DIY kit for off-center-fed (windom) antennas, among other things.
1:4 BalUn 600 Watt self-build kit 1.8 – 30 MHz, with solid strain relief. This 1:4 BalUn is constructed from two FT240-43 ferrite toroidal cores. On the first toroidal core a 1:1 current BalUn is built up. It takes care of the transition from unbalanced (coax) to balanced antenna. This BalUn has a fantastic common mode current attenuation of over 30 dB. The second toroid is responsible for impedance adjustment from 50 ohms to 200 ohms. Many BalUn manufacturers only look at the impedance matching but forget to look at the common mode current attenuation. This BalUn scores very well on both levels. Now with a handy mounting plate to attach both ring cores, so gluing is no longer necessary.
The 1:4 BalUn 600 Watt can be used for off-center-fed antennas, among other things. The off-center-fed antenna (windom) is a popular multiband antenna. These antennas have many advantages. The antenna can be used on many bands, the antenna is often easy to place due to the 1/3, 2/3 ratio in the antenna legs. By using a good BalUn, Common mode current are prevented, which also reduces interference from your direct environment. This antenna needs no ground or counter capacitance.
The main reason for using a BalUn is to make sure that the coax cable is not part of the antenna system and that it will radiate undesirable. This has all sorts of nasty effects, think of: interference, EMI, RFI disrupted radiation pattern of the antenna, restless noise level. This last point is because not only does the coax cable’s shield radiate when you transmit, but the shield also works as a receiving antenna.
1:4 BalUn 600 watt components
This kit includes:
- IP65 enclosure 100x100x55 mm
- 2x Ferrite Ring Core Amidon FT240-43
- Winding wire 18 AWG – 8x 85cm PTFE 19 x 0.25 mm copper “Silver plated”
- PL 259 Chassis
- Toroid mounting plate
- 4x M3 spacer
- 4x Stainless steel M3 6 mm screws
- 4x stainless steel M3 washer
- M3 Cable lug
- 2x M5 Cable lug
- 2x stainless Steel (A4) M6 eye (Strain relief)
- 2x Stainless Steel M6 Nut
- 2x Stainless steel M6 washer
- 2x stainless steel M6 Spring washer
- 2x Stainless Steel M5 Bolt 25mm
- 2x stainless steel M5 wing nut
- 4x Stainless Steel M5 Nut
- 4x Stainless steel M5 washer
- 2x stainless steel M5 Spring washer
- 4x stainless steel M5 toothed washer
- 4x stainless steel M3 Bolt 12mm
- 4x Stainless Steel M3 Nut
- 4x Stainless steel M3 washer
- 4x stainless steel M3 toothed washer