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Design of Wide Band RF Transformer on Ferrite Tubes

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ANTENTOP- 01- 2018 # 022

Design of Wide Band RF Transformer on Ferrite Tubes

Wide Band RF Transformers on Ferrite Tubes

Credit Line: http://cqmrk.ru/articles/63.html

Ferrite transformer on ferrite tubes performs several functions at once: this one does match of the feeding coaxial cable to the antenna (or transform impedance of the antenna to impedance of the coaxial cable), balances RF current at feeding terminals of a symmetrical antenna and suppresses the common-mode current on to outer side of the coaxial cable braid.

It is possible to find on the sale in the internet lots different ferrite tubes. Some ferrite tubes may be saved from old CRT monitors where the ferrite is used as noise-suppressing chokes on communication cable. For the transformer it was used ferrite tubes marked as FRR-9.5.

The tube has dimensions (ID x OD x L) 9.5x17.5x35. When you will be looking for ferrite tubes in the internet keep in the mind that the best ones should have permeability 600. Figure 1 shows FRR-9.5 ferrite tubes.

Figure 1

Ferrite Tubes Marked as FRR-9.5

Four of these tubes, placed side by side, and two rows from the two tubes placed in bridge, form binocular ferrite core that could be used for making wide band RF transformer.

 Table 1 Data of Transformers Made of on Ferrite Tubes Number Turns of Primary Winding Number Turns of Secondary Winding Transformer Ratio U Primary/ U Secondary Transformer Ratio R Primary/ R Secondary Ratio at input R= 50 Ohm 1 1 1:1 1:1 50:50 1 1,5 1:1.5 1:2.25 50:112.5 1 2 1:2 1:4 50:200 1 2.5 1:2.5 1:6.25 50:312.5 1 3 1:3 1:9 50:450 1 3.5 1:3.5 1:12.5 50:625 2 1 1:0.5 1:0.25 50:12.5 2 1,5 1:0.75 1:0.56 50:28 2 2 1:1 1:1 50:50 2 2,5 1:1.25 1:1.56 50:78 2 3 1:1,5 1:2,25 50:112,5 2 3,5 1:1,75 1:3 50:150 2 4 1:2 1:4 50:200 2 4,5 1:2,25 1:5 50:250 2 5 1:2,5 1:6,25 50:312.5 2 5,5 1:2,75 1:7,56 50:378 2 6 1:3 1:9 50:450 2 6,5 1:3,25 1:10,56 50:528 2 7 1:3,5 1:12,5 50:625

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