Ham Radio Site - [ RF (CMC) CHOKES ] - DJ0IP

 

 

 

RF-CHOKES

 

 

 

       Common-Mode-Current  Chokes

 

         (A GET OUT OF RF- HELL FREE  CARD)

 

Unwanted RF in the shack due to Common Mode Current (CMC) on the coax can be nasty. Besides burning your fingers on the key or burning your lips on the mic, it can also cause some devices to fault. Worst case it can cause TVI or BCI, etc.

 

To help reduce CMC on the coax, an RF choke (or CMC Choke) can be placed at the antenna feedpoint. In this case we call it a "Balun" or "Choke-Balun".

 

It is also important to place a second Choke just before the coax enters the house, to help prevent pickup of noise by the feedline, which negitively affects your receiver.

 

There are several ways to accomplish this;

some good, some better, some not so good.

 

I will NOT try to explain all of the theory here - just enough theory that you understand what is going on.  

 

THIS  SECTION  CONTENTS:

  • START HERE  . . . . . . . . . . . things to understand before you read about chokes
  • Simple Basic Theory  . . . . . Explains how chokes help - in Q&A form.
  • Important Background Info . . (not yet written)
  • Different Kinds of Chokes  . Shows 5 different types of RF Chokes
  • Things to Watch Out For  . . Warnings and Explaination of Differences
  • Where to Use Chokes   . . . . Comments by Jim Brown, K9YC)
  • Which Choke - Where   . . . . Guidelines for what to deploy, where and when)

This is where I learned about this topic before beginning my own research:

 

LINKS to more Theory:

 

If you have more severe problems, then it is  helpful to study the information published by the real experts on this topic.  

 

These are CLICKABLE-LNKS:

 

W1HIS    -   W7EL   -   GM3SEK    -    G3TXQ    -    K9YC-1    -    K9YC-2

 

I can't say which is better - they are all excellent!

 

Google

http://DJ0IP.de

.....(Search on THIS site.)

N E W

A Short Video by W8JI

Power loss in SWR?

Standing Up for Standing Waves

by Bill Hayes, AE4QL

N E W

OCFD ANTENNA

PRESENTATION

ANTENNAS by DJ0IP

( Info-Only; NO SALES! )

Spiderbeam on Facebook:

Antenna Matchbox

SHOOTOUT!

(5 different Shootouts)

SWR Meters

Make You Stupid

 

Rob Sherwood's

Elecraft K4D

Test Review

BRAND NEW

from Spiderbeam:

Mini "SOTA" Pole

* * * * * * * * *

Yaesu FTdx-10

vs.

Icom IC-7300

* * * * * * * * *

QRP RADIO REVIEWS

by Rob Sherwood NC0B

The Cost Of

Transceiver

Performance

(AUF DEUTSCH)

Mikrofone

Rob Sherwood Test:

Yaesu FTdx-101D

NEW

SHERWOOD VHF/UHF

TRANSCEIVER TESTS

NEW

IC-7300

Linear Amplifer

Interfacing

Rob Sherwood,

NC0B

TEST REVIEWS

KnWd.TS-890S

ICOM IC-7610

ICOM R-8600

ICOM IC-7300

ICOM IC-7851

and many MORE

Transceiver SHOOTOUT

TS-890S  vs.  IC-7610

by Rob Sherwood, NC0B

   Spiderbeam FG Pole

Photo: Nischal Nethrananda

A fun film about

Ham Radio Outdoors

(not just in Tenerife)

FUNKAMATEUR

Test Review:

Aerial-51 807-L

OCFD Antenna

(English & German)

My WRTC-2018

(nearly) Invisible Pole

An Aerial-51

Sponsored Expedition:

NEW Spiderbeam

40m Add-On Dipole

for its Yagi Antennas

(WRTC Special)

 

WHY DIPOLES

 

SHOULD USE

 

A BALUN

 

INTRODUCING

The Rope Fuse

Rob Sherwood:

ANAN 7000DLE

vs

ICOM IC-7610

In CQWW 160 CW 

N E W

SHERWOOD'S SHOOTOUTS

Icom vs. Kenwood

New Antenna

Aerial-51

Model 807-L

Lightweight for

80/40/20/17/15/12/ 10/6m

 

 

Contest University

2017

 

Monticiari Hamfest

Linear Amplifier

Interfacing

S-Meter Accuracy

by Rob Sherwood

(SSB-06)

IOTA CONTEST WINNER

"OZ/DL5CW"

USES AERIAL-51

MODEL 807-UL

ANTENNA

Special purpose Aerials:

Ultra-Lightweight antennas for expeditions and stealth applications.

OpenWire-Fed

Antennas

 

- - - -

TUNER BALUNS

Home-Brew D-i-Y

Tuner Balun

 

Simple Multi-

Band Vertical

on a 12m Spiderpole

 

 

160m INVERTED-L

on a 12m Spiderpole

 

 

80m INVERTED-L

on a 12m Spiderpole

 

 

Rob Sherwood

Test Drives

the FLEX 6700

in CQWW DX 160m

 

+ 

 

(other)

Transceiver Tests

 

---------------------

UPDATES:

THE RUBBER BALUN

 |

BAD BALUNS

 |

What's Wrong with OCFD

 

 -----------------

 LL-TUNER "S-MATCH"

added to my

symmetrical tuner page.

HERE

 

----------------------

  PROGRESSING: 

 LOTS OF NEW CONTENT IN THE SECTION:   

ANTENNA MATCHBOXES 

MODERN ANTENNAS

 

WIRE BEAMS

It's time to build antennas!  Visit:

Spiderbeam Antennas

 

DISCLAIMER

ALL NEWS

 

 

*******************

VISITORS:

 Since JAN-2013

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