Questions tagged [transformer]

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4
votes
0answers
46 views

How to measuring ferrite core efficiency vs frequency

There is an unknown ferrite toroid. I would like to figure out whether it can be used in an audio transformer, or maybe in a 1:4 transformer on given HF frequency. The experiment I came up with is ...
1
vote
2answers
65 views

Toroid Coupling Issue in Common-base Amplifier

I'm working on an old school VFO for the 15 meter band based on a JFET Hartley oscillator. The plan is to follow the oscillator section with a JFET buffer, then a CB amplifier (for increased reverse ...
5
votes
1answer
375 views

How to build a balun transformer for 2m RX with low insertion loss

I'm looking into ways to match a 137 MHz RX dipole antenna to an unbalanced coax + amplifier. I know there are several types of baluns which can be categorized under magnetic baluns (where there are ...
0
votes
2answers
503 views

Broken IF Transformer (tiny and 455 KHz)

I broke so called 'IF transformer' on my radio. I was just slightly trying to regulate it to follow an instructions that is found on Wikihow page. My aim was to listen to the conversations of pilots ...
6
votes
1answer
2k views

How can a quarter-wave transmission line transformer be implemented with lumped elements?

Sometimes designs call for quarter-wave sections of transmission lines. There are some situations when using actual transmission lines would not be practical: The necessary characteristic impedance ...
8
votes
1answer
600 views

What's this “crossover” toroid winding called and what is its purpose?

I am winding an EFHW matchbox and many of the designs I've found (including the diagram provided with the kit I bought) include a sort of "twist" when winding them: (Image taken from this post and ...