Copper Talk » Ask The Tech » Antennas » BALUN / UN-UN ? Help!!! « Previous Next »

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

Joey_migs
Junior Member
Username: Joey_migs

Post Number: 26
Registered: 9-2009
Posted on Saturday, October 03, 2009 - 12:57 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I am trying to construct a 11 meter dipole.
I made a 1.5:1 transformer (to better match the 72 ohms dipole feed to the 50 ohms transceiver _ like the an effectiveness ant possible.I want the feedline matched the feedpoint of ant, and 1:1 SWR at the base into the coax. I used a FT-240-61 ferrite toroid, a trifilar winding of no. 14 enamel coated copper wire and a couple of capacitors. I tested the setup using a RG-8 to transformer to RG-59 terminated with a 72 ohm dummy load - the SWR was less than 1.3:1 across the band.
My question is the dipole is balanced and the coax is unbalanced will this cause any problems?

Can I just loop the coax coming from bottom of the ANT> 4~5 times around a 2 inch PVC pipe (as a choke) to impede the current from riding the braiding of the coax. i am i right?

Thx, Miggs
Top of pagePrevious messageNext messageBottom of page Link to this message

Tech237
Moderator
Username: Tech237

Post Number: 1230
Registered: 4-2004


Posted on Saturday, October 03, 2009 - 2:24 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Joey - please see then answer to your prior question, as the answers remain the same. A coaxial choke at 11m needs to be around 6" diameter to have the best chance of working correctly, and at least 2-3 turns.

As I mentioned last time, throw the "transformer" away, as it is really two tuned circuits and is NOT giving you an accurate reading on the SWR of your antenna, and either run straight to the antenna with a coax choke, or insert a proper 1:1 balun inline.
Simon
Tech237
N7AUS
.
I thought he said, "there was no rust for the wicked, and I own an MGB"
Top of pagePrevious messageNext messageBottom of page Link to this message

Joey_migs
Junior Member
Username: Joey_migs

Post Number: 28
Registered: 9-2009
Posted on Sunday, October 04, 2009 - 12:24 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Got you, Thanks

Joe

Add Your Message Here
Post:
Username: Posting Information:
This is a private posting area. Only registered users and moderators may post messages here.
Password:
Options: Enable HTML code in message
Automatically activate URLs in message
Action: