Page: 1 2
29fb002
Registered user
Global user
Registered: 09-2009
Posts: 12
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
A simple 1:1 Choke Balun
This is a very simple 1:1 Balun to make and costs about 4 euro , ideal for 11m center fed dipole antenna
http://hamuniverse.com/balun.html
|
|
10/Sep/2009, 1:12 am
|
Send Email to 29fb002
Send PM to 29fb002
Blog
|
crimso
Registered user
Global user
Registered: 08-2009
Posts: 92
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: A simple 1:1 Choke Balun
I use these all the time, the basic maths is about one quarter wave of coax coiled, makes a semi decent ugly balun.
I normally use a s couple of loops just cable tied or insulating taped together with a ferrite clip on choke each side & this makes a brilliant RF choke, that is not as ugly as it could be.
|
|
10/Sep/2009, 4:57 pm
|
Send Email to crimso
Send PM to crimso
|
Kaosss
Moderator
Global user
Registered: 04-2008
Location: County of Flintshire, N. Wales
Posts: 791
Karma: 4 (+4/-0)
|
|
Reply | Quote
|
|
Re: A simple 1:1 Choke Balun
I have made one of these for my beam which helped a lot with TVI. I made it using 21ft of coax. It sounds as if I dont need to use that length if only using 11meters? I need one now for my vertical - A99, so about 2.75 meters would work?
Al
---
Al -163FB777 - N.Wales, UK
Kenwood TS-480SAT, MC-60A mic, 827-Base + 3 elli beam
K40 when mobile
|
|
13/Sep/2009, 11:29 pm
|
Send Email to Kaosss
Send PM to Kaosss
|
crimso
Registered user
Global user
Registered: 08-2009
Posts: 92
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: A simple 1:1 Choke Balun
6 turns of RG-58 at around 4.5 inches will be about right at 10 meters.
If you want the maths K1TTT has it on his page
http://www.k1ttt.net/technote/airbalun.html
|
|
14/Sep/2009, 9:45 am
|
Send Email to crimso
Send PM to crimso
|
Disgwylfa
Registered user
Global user
Registered: 06-2009
Location: the Vale of Glamorgan
Posts: 20
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: A simple 1:1 Choke Balun
I've put one on each of my 11m verticals. Dramatically reduced the RFI into landline phones in the house and seemed to reduce "noise" on RX.
Had to use narrower formers on mine due to lask of anything around 4.5 inches, but works fine on a bit of old plastic drainpipe from the greenhouse.
---
Cheers,
Steve
163-FB-105
|
|
14/Sep/2009, 10:16 pm
|
Send Email to Disgwylfa
Send PM to Disgwylfa
|
yamanx1
Head Administrator
Global user (premium)
Registered: 09-2007
Location: In a world of my own
Posts: 2332
Karma: 5 (+5/-0)
|
|
Reply | Quote
|
|
Re: A simple 1:1 Choke Balun
Why cant you put the pole through it?
Or can you?
|
|
23/Sep/2009, 6:26 pm
|
Send Email to yamanx1
Send PM to yamanx1
|
crimso
Registered user
Global user
Registered: 08-2009
Posts: 92
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: A simple 1:1 Choke Balun
First a RF Balun is in reality a RF Choke & not a Balun.
It deals with the problems of the coax becoming part of the antenna when that is unwanted. And it thus deals with things like the mast & other close by conductive materials causeing RFI as a result of the coax radiating RF.
So the idea of an ugly balun in part is to stop the RF on the coax before it reaches the mast.
An Ugly Balun is an Air wound choke & as such should not be wound onto a conductor & if it was it would alter the impedence & thus become a balun & not choke.
|
|
23/Sep/2009, 7:16 pm
|
Send Email to crimso
Send PM to crimso
|
yamanx1
Head Administrator
Global user (premium)
Registered: 09-2007
Location: In a world of my own
Posts: 2332
Karma: 5 (+5/-0)
|
|
Reply | Quote
|
|
Re: A simple 1:1 Choke Balun
Sorry, yes I understand that. But why cant the mast run through the plastic piping? Instead of a stand off, or lying at the bottom. I would say an RF choke would work best as close to the antenna connection as possible? 
|
|
23/Sep/2009, 9:02 pm
|
Send Email to yamanx1
Send PM to yamanx1
|
56ww
Registered user
Global user
Registered: 08-2009
Posts: 81
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
 Re: A simple 1:1 Choke Balun
Crimso have a point,
Its stop currents flowing back on coax jacket, rf have to go between hot lead and jacket. If lots of rf are on jacket that can conductive to others "metals" and also back to finals trans. there is some toroids choke coaxbaluns what are very easy to do, just round few turns clockwise and to otherside few turns unclockwise. Also can put ferrite rings (click to close) on coax, but make sure to using right ferrite material, I had bouth in use and toroid is better, it resist qrn at receive. I had long time a go uglybaluns on 80m and if I remember righ, it was rounded coax maybe 5 times 1 foot diameter whitout tube, and was efficent dipole what I ever had to 80m. 130W out and no tvi or swr.
if there is wrongly tecnical digres
. Please make corections any time, its better if evrything is right on this case.
I have to read more literature of that.
Living in a all good faith is not good for knowledge.
73'mike
|
|
23/Sep/2009, 9:21 pm
|
Send Email to 56ww
Send PM to 56ww
|
Add a reply
Page: 1 2
Link to us
- Blogs
- Hall of Honour
- Chat
|
You are not logged in (login)
Board's time is: 27/Nov/2009, 9:10 am
|
|
|
i use one on a 40m ish dipole and also used the smaller version for 11m and deffo reduced TVI and RF feedback. mines more ugly than that 
