You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
66 lines
2.3 KiB
66 lines
2.3 KiB
+++
|
|
title = 'I built some ferrite chokes'
|
|
aliases = '/posts/2023-09-23-i-built-some-ferrite-chokes'
|
|
summary = '''I built two ferrite chokes and measured them already,
|
|
but I never presented the results to the internet audience :winking_face:'''
|
|
date = '2023-09-23T21:22:14+0200'
|
|
#lastmod = ''
|
|
categories = [ 'amateur-radio' ]
|
|
tags = [ 'diy', 'portable' ]
|
|
|
|
+++
|
|
|
|
Before we start: there is a short wikipedia article about [Ferrite beads][1]
|
|
that I wanted to share with you. Just in case you are new to the hobby and want
|
|
a quick read about this topic.
|
|
|
|
[1]: https://en.wikipedia.org/wiki/Ferrite_bead
|
|
|
|
## Calibrate the nanoVNA(-F)
|
|
|
|
Going through the calibration process with the full lenght of the used
|
|
adapters. All measurements happen on port S11 except <kbd>ISOLIN</kbd>, where
|
|
we connect both ports together.
|
|
|
|
1. <kbd>OPEN</kbd>
|
|
Leave the cables as they are (open).
|
|
2. <kbd>SHORT</kbd>
|
|
Connect the red and black croco clips (shorten the circuit).
|
|
3. <kbd>LOAD</kbd>
|
|
Clip a 50Ω load to the croco clips (red one to the core, black one to the shielding).
|
|
4. <kbd>ISOLIN</kbd>
|
|
Leave the load connected. (Maybe add another one to the second cable on the port S21).
|
|
5. <kbd>THRU</kbd>
|
|
Shorten both cables (S11 & S21; red to red, black to black).
|
|
|
|
## PL259 socket
|
|
|
|
This is my selfmade choke for the good old PL259 sockets.
|
|
|
|
|
|
|
|
There are **9 turns of RG174** on a **FT-140-43** ferrite core.
|
|
|
|
Connecting the red croco clip from port S11 to the shield of one PL259 socket
|
|
and the red croco clip from port S21 to the shield of the other PL259 socket.
|
|
Also connect both black croco clips together.
|
|
|
|
|
|
|
|
I got -30dB at 14.340 MHz and -25dB at 3.610 MHz.
|
|
|
|
## BNC socket
|
|
|
|
I made a smaller version with BNC sockets for portable operations as I switched
|
|
my gear to a more lighter setup (which made me use QRP transceivers basically).
|
|
|
|
|
|
|
|
We measure the choke like the first one: connect the core (red croco clips) with
|
|
the choke's shield and shorten the shield of the nanoVNAs ports (black croco clips).
|
|
|
|
|
|
|
|
|