Menu

Baluns?

Search this Thread

Prev

Previous Post

Next Post

Next

#11

Report Post

Old

September 3rd 08, 01:04 PM posted to rec.radio.amateur.antenna

Cecil Moore[_2_] Cecil Moore[_2_] is offline

Cecil Moore[_2_] is offline

external usenet poster

First recorded activity by RadioBanter: Mar 2007

Posts: 3,521

Default

Baluns?

wrote:
Many US amateurs do not understand how a balun works.

Quoting "The ARRL Antenna Book" re a w2du balun:
"Maxwell made a test balun by slipping 300 #73 beads
over a piece of RG-303 coaxial cable. The impedance
of the outer conductor of the cable measured
4500+j3800 at 4.0 MHz."

The differential current emerging from the inside
of the coax braid encounters, e.g. 30 ohms, looking
toward the antenna. It encounters 4500+j3800 = 5890
ohms looking back down the outside of the coax.
Ohm's law does the rest.

Without the beads, that differential current might
see an impedance lower than 30 ohms looking back
down the outside of the coax for certain unfortunate
lengths of coax. The common-mode choking impedance
forces ~equal currents in each dipole leg at the
BALanced antenna to UNbalanced coax junction. That
common-mode choking impedance causes the balun
function to occur.
--
73, Cecil http://www.w5dxp.com

Reply With Quote

Reply With Quote

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search
Display Modes
Switch to Linear Mode Switch to Hybrid Mode Threaded Mode

Posting Rules
Smilies are On [IMG] code is On HTML code is Off Trackbacks are On Pingbacks are On Refbacks are On

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Baluns..	JohnM	CB	4	September 16th 05 04:51 AM
Baluns	B.Binggeli	Antenna	0	August 23rd 05 02:28 PM
Baluns	Peter Barbella	Homebrew	1	April 20th 05 01:54 AM
1 to x baluns	pegge	Antenna	20	February 1st 05 05:26 AM
Baluns	JEFF UK	Antenna	6	February 18th 04 09:01 PM

All times are GMT +1. The time now is 10:06 PM.

About Us

"It's about Radio"

Contact Us RadioBanter forum home Privacy Statement

Copyright © 2017