Questions tagged [transformer]
Impedance matching transformers as related to amateur radio.
10
questions
6
votes
1answer
1k 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 ...
8
votes
3answers
2k views
Can a 1:1 transformer be used as a protection from static electricity?
It's well-known that under certain conditions verticals and dipoles can gather static charge, which is a common reason of transceiver damage. There are several ways to solve this issue. Some hams ...
2
votes
0answers
29 views
How to cut phasing/transformer coax in a right way?
I'm building RHCP crossed dipole for 137 MHz satellites reception (I'm using 137.5 as a central frequency). My calcs are:
frequency is 137.5 MHz
λ is 2.18 m
one dipole leg length equals to the λ/4 so ...
3
votes
0answers
229 views
9:1 unun material and power loss
I need to build another 9:1 unun and I start searching for my toroids... (I have build 2-3 something like 4 years ago)...
In parallel I checked on Google about the correct toroid etc so I found 2-3 ...
-3
votes
1answer
145 views
Carrier telephone system adaptation
In amature radio, users can use what is called a phone patch to enable them to use a phone to establish connection to another party or user.
Phones are usually two wire and dont lend themselves to ...
5
votes
1answer
1k views
How to build a balun transformer for 2m RX with low insertion loss
I'm looking into ways to match a 137MHz 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 ...
1
vote
2answers
83 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 ...
6
votes
1answer
4k 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 ...
0
votes
2answers
651 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 ...
8
votes
1answer
965 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 ...
