Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Magnetic RFI  (Read 4100 times)
RSHIRE22
Member

Posts: 0




Ignore
« on: December 06, 2013, 06:50:07 AM »

I homebrewed a magnetic loop antenna which works well but as predicted magnetic rfi is wreaking havoc with my computer especially the clock which I need to run JT-65A. I use a coax choke in the shack and a toroid isolator at the feed point which don't suppress magnetic rfi (at least not in my case). How do I suppress magnetic rfi in shack?

Any suggestions are appreciated.
Logged
RSHIRE22
Member

Posts: 0




Ignore
« Reply #1 on: December 06, 2013, 09:04:11 AM »

I guess magnetic rfi is EMI.
Boy there is an abbreviation for everything!
Logged
KB4QAA
Member

Posts: 2450




Ignore
« Reply #2 on: December 06, 2013, 10:54:43 AM »

Magnetic RFI.  sigh. Wink

Try the term "Small Loop Antenna" and we can start to get away from the idea that these antennas have special properties or unique RFI modes.  

Your problems are quite common, and asked several times every week.  The answers are repeated several times every week.  Smiley   I recommend reading other posts in the forum for better understanding.

Anyone who thinks that having antennas inside or close proximity to a house, attic, apartment or townhouse (like me) without a very high probability of RFI problems is naive.  

The Standard Laundry List:
-Reduce power.  Find a level that doesn't cause problems.
-Change bands.  Operate on bands that don't cause problems
-Re-orient the antenna
-Move the antenna higher, farther away
-Good housekeeping:  Straighten up cables, don't cross, coil them up, put frequency appropriate Mix chokes on all cables close to each end.
-Use chokes, isolation transformers/baluns in the antenna coax
-If using amplified speakers, switch to passive speakers
-Study up on shack ground systems.  Eliminate ground loops in/between coax and 'ground wires'. 
-Keep ground leads/wires/braid/foil wide and as short as possible.
-Don't use electrical grounds for RF purposes.
-Avoid RF grounds that are resonant lenghts or longer, e.g. 1/4wl or longer.

That's a start.  good luck.  b.
« Last Edit: December 06, 2013, 11:03:10 AM by KB4QAA » Logged
RSHIRE22
Member

Posts: 0




Ignore
« Reply #3 on: December 06, 2013, 09:27:42 PM »

Thanks b. I moved my transceiver about five feet away and put aluminum foil on all the cables. I am running 50 watts with about 15% efficiency. So far it's better now running JT-65HF. I can't use WSJT at all. At 49 seconds past each minute the software clock freeses.

I've read through your suggestions and see which are practical.

Ron
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!