Charlie Tango 11m DX Radio Group Forum
Would you like to react to this message? Create an account in a few clicks or log in to continue.


Welcome to the Charlie Tango DX Group. The home of ALL things Radio - CB, 11m DX, Amateur, PMR446, PLD, Network and Data. We welcome all radio enthusiasts of all knowledge levels. Join today and claim your own unique World Famous CT Call-sign
 
HomeEventsCalendarFAQSearchRegisterLog in
New eQSL Email Service: Exchange eQSL cards quickly and easily with your very own eQSL email address like this... 26CT000@eQSL.me or 26CT000@charlietango.co.uk - See Latest News forum for more details.
Latest Buxton 2020 News: Unfortunately, due to the Covid-19 pandemic we have had to cancel this year's Buxton date. Sorry for any inconvenience.
Navigation
Useful Radio Sites
Log in
Username:
Password:
Log in automatically: 
:: I forgot my password
CT Bill Board





Views This Year
All Time Views
Classified Adverts

Latest topics
Keywords
ALINCO call list Mckinley yaesu Sirio Calling callsign midland radio president frequency chart lincoln sign antenna ss9900 power 9900 division Buxton Mobile alan 6900n bazooka tickets
QRZ Database
 

 Choke for 11 and 10m

Go down 
AuthorMessage
Matt86
CT Directors
CT Directors
Matt86

Call Sign : 26ct2767
Posts : 221
Times Thanked : 4
Join date : 2019-06-27
QTH or Location : Swindon
Equipment Used : Yaesu ft818 , yaesu 8900r , yaesu ft950, stalker 9
Age : 33

Choke for 11 and 10m Empty
PostSubject: Choke for 11 and 10m   Choke for 11 and 10m Icon_minitimeMon Jul 08, 2019 11:15 pm

Has anyone used a choke either under there antenna and near the rig ?

If so was there any improvements ?

I dont really want to have many joins with 1:1 balances as a insulator. Any other ideas and will be using aircell 7 coax .

Matt
Back to top Go down
View user profile
The DB
New Member
New Member


Posts : 11
Times Thanked : 2
Join date : 2019-06-29

Choke for 11 and 10m Empty
PostSubject: Re: Choke for 11 and 10m   Choke for 11 and 10m Icon_minitimeTue Jul 09, 2019 8:16 pm

I've seen some antennas that needed a choke, and others that didn't.  It depends on the antenna system.

If you add a choke and it changes your SWR readings, then you need the choke.

Also, some antennas benefit from the choke being not right at the feed point, like the a99 which works better with the choke further away from the antenna's feed point.  Nine feet (I think about 2.7 meters) is good, and it doesn't have to be exact, close is fine.

If you have an antenna with a set of full length radials, you likely don't need a choke.


The DB
Back to top Go down
View user profile
KKD3088
New Member
New Member


Call Sign : KKD3088
Posts : 1
Times Thanked : 0
Join date : 2019-07-21
QTH or Location : Long Island, New York
Equipment Used : Various vintage tube radios and some home built equipment

Choke for 11 and 10m Empty
PostSubject: Re: Choke for 11 and 10m   Choke for 11 and 10m Icon_minitimeSun Jul 21, 2019 4:18 am

Matt86 wrote:
Has anyone used a choke either under there antenna and near the rig ?

If so was there any improvements ?

I dont really want to have many joins with 1:1 balances as a insulator.  Any other ideas and will be using aircell 7 coax .

Matt


A common mode choke (CMC) is advisable on any half-wave or five-eighths wave antenna without ground radials directly below the feed point. It will prevent common mode currents from flowing on the OUTSIDE of the coax. RF should only exist on the center conductor and the INSIDE of the coax shield, not on the outside.

Without the CMC, undesired RF can end up back in your operating position and also cause skewing of your radiation pattern from the antenna. This has always been a problem with the IMAX-2000 and the A99.

A CMC for 27 MHz can be made easily by winding 16 turns (side by side, solenoid style) of RG-8X on a 6.5" section of 2" PVC pipe.

If using RG-8, RG-213, RG-214, or LMR-400, the dimensions will be different.
Back to top Go down
View user profile
 
Choke for 11 and 10m
Back to top 
Page 1 of 1

Permissions in this forum:You cannot reply to topics in this forum
Charlie Tango 11m DX Radio Group Forum :: Help and Discussion Forums :: Antenna Discussion-
Jump to: