AM Radio Antenna - Page 3 - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 11th March 2009, 03:47 AM   #21
infinia is offline infinia  United States
diyAudio Member
 
infinia's Avatar
 
Join Date: May 2005
Location: Californication
1) Try common mode choke described above
2) You could also try your RFC in the power supply ground lead.
3) Also try a battery instead of the PS.
4) Don't leave any scope probe grounds attached.


All are fixes are for the same thing...
The bottom of your ant loop is attached to the ground (ultimately gnd of the building AC wiring?) of your SE radio unbalancing it.
__________________
like four million tons of hydrogen exploding on the sun
like the whisper of the termites building castles in the dust
  Reply With Quote
Old 11th March 2009, 01:07 PM   #22
bwaslo is offline bwaslo  United States
diyAudio Member
 
bwaslo's Avatar
 
Join Date: May 2006
Location: Cinciinati, OH
Dunno if you tried it already, but have you tried reorienting your antenna? Loop antennas are very directional, you might be pointing right into a null. Also, orientation should usually be with the axis parallel (not perpendicular) to the earth. Move it around before you give up on it.
  Reply With Quote
Old 11th March 2009, 08:00 PM   #23
Mark245 is offline Mark245  United States
diyAudio Member
 
Join Date: May 2006
Ok thanks! I will try all of this and let you know how it goes.

mark
  Reply With Quote
Old 27th March 2009, 04:25 PM   #24
Mark245 is offline Mark245  United States
diyAudio Member
 
Join Date: May 2006
Thanks Infinia! The common mode choke seems to be the answer to the problem. Do you know why this fixes the problem? I read part of the link from your previous post but it still is not quite clear to me. At least I have a radio that works now without having to touch the antenna. I guess my hand was acting as a common mode choke? Thanks!
  Reply With Quote
Old 28th March 2009, 01:42 AM   #25
infinia is offline infinia  United States
diyAudio Member
 
infinia's Avatar
 
Join Date: May 2005
Location: Californication
Hi Mark
Glad you got your loop working.
Re> common mode choke. It's really called a balun in this application. The real simple explanation is that itís useful as buffer between a balanced antenna and an unbalanced circuit.
BALUN = BALance + UNbalanced
Itís also used to keep the transmission line from unduly interacting with the antenna and possibly re-radiating the EM energy collected. Google antenna and balun for more indepth discussion.

edit>
Another way to look at it
The balun choke looks like a large inductance for currents traveling down both conductors (common mode). And looks like a low inductance for differential currents ie balanced currents returning to and from the source (they cancel each others magnetic field in the core).
__________________
like four million tons of hydrogen exploding on the sun
like the whisper of the termites building castles in the dust
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
car antenna coki Car Audio 3 11th August 2007 12:35 PM
car radio antenna petercampusa Car Audio 1 29th April 2006 09:21 AM
Antenna ? fortuosity Everything Else 1 17th October 2005 11:14 AM
Wiring for Home XM Radio Antenna joeytt64 Everything Else 0 23rd February 2005 07:40 AM
What do you think about this antenna ? darkm4n Parts 0 6th March 2004 10:47 PM


New To Site? Need Help?

All times are GMT. The time now is 06:17 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2