The use of a line output transformer core to make a balun.
Be careful when removing the core as it is very fragile! 10 windings were made both top and bottom. They behave like 100 ohm transmission...
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Receiving loop antenna with 3 turns i.s.o. 2 turns.
Height and width of the loop are 1 meter. This means that one turn = 2.80 meters. In this case i have used tree turns = 8.40 meters. New...
Receiving loop antenna for indoor or portable use.
Height and width of the loop are 1 meter. This means that one turn = 2.80 meters. In this case i have used two turns = 5.60 meters. I...
Loop On Ground Antenna
The feedpoint Square with a side = 5 meters Hard to see on the picture. top left is the feedpoint Used material: 1 core of 73 material...
Guanella 1/6 current balun.
Pictures: Schematic: U out = 2.5 x U in ==> Impedance Out = 2.5 x 2.5 = 6.25 x impedance In @ 50 Ohms in, Out = 312 Ohms. Measuring...
Guanella 1/9 current balun.
Picture: Schematic: Input: 3 transmission lines with an impedance of 150 ohms in parallel = 50 Ohms, Output: 3 transmission lines with an...
Building a QRO 1/49 transformer for end fed antenna.
Used material: - 3 cores Amidon 240-43 - copper wire 1.8 mm diameter - PTFE tube with 2 mm internal diameter and 3 mm outside diameter -...
The Turrin balun
Used material: FT240-43 Schematic: Insertion loss: Return loss: Common mode rejection:
Guanella 2 wire balun versus Ruthroff 3 wire balun.
Guanella 2 wire Ruthroff 3 wire Schematic: Guanella 2 wire Ruthroff 3 wire Return loss: Guanella 2 wire Ruthroff 3 wire...
The Ruthroff balun (1/1 3 wire version).
Used material: AmidonFT240-43 core. Top view Bottom view This is the way I think it should be made. Schematic: Insertion...
Guanella balun 1: 1 comparison between two and four conductors.
Used material: Amidon FT240-43 cores. LEFT = 2 conductors RIGHT = 4 conductors Left: transmission line with an impedance of 100 ohms....
Building and measuring a Guanella 1:4 balun with Wurth cores 74270191
For building descriptions, see my previous blogs. Return loss measurements: Insertion loss measurements: Insetion loss @ 14 MHz = 0.2 dB...
1/1 Current Balun with 15 turns on Wurth core 74270191 for better low frequency behavior.
Insertion loss: Return loss: Common mode rejection:
1/1 Current Balun with 10 turns on Wurth core 74270191
On both sides, i placed 10 turns teflon wire. Insertion loss: Worst case = 0.09 dB @ 30 MHz. This means a power loss of 2 %. Return loss:...
Measurements on output transformer final amplifier TS440.
The TS440 power amplifier is a push-pull amplifier with a very low output impedance. To make a conversion to 50 ohms, a 1/16 impedance...
Measurments on Kenwood YK-88CN CW Narrow filter.
Input / output impedance = 600 Ohms Measuring setup: Transformer impedance ratio = 600 / 50 = 12 I have ended with 3 turns / 10 turns....
Measurments on muRata CFJ455K 14
Input / Output impedance = 2.000 Ohms Measuring setup: Transformer impedance ratio = 2.000 / 50 Ohms = 40 I started with 2 turns / 13...
Analysis of a Kenwood TS 440 filter unit.
How does it work? Depending on the selected frequency, one of the six available filters is activated. This is done by controlling a relay...
Bandpassfilter for 80 meter band (3.5 MHz) with Amidon T50-2 cores.
5,5 µH coil versus 55 µH coil. Picture: Schematic: 34 turns = 5.5 µH capacitor is approx. 320 pF. 104 turns = 55 µH capacitor is approx....
Bandpassfilter for 40 meter band (7MHz) with Amidon T50-2 cores.
Important: only for receivers. This filter can not handle transmitted power. Picture: The Kank 3334 transformer from Toko has on one...