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: Really high voltage  (Read 1478 times)
KB1GTX
Member

Posts: 459




Ignore
« on: February 09, 2012, 03:30:15 PM »

http://www.youtube.com/watch?v=B1O2jcfOylU
Logged
KB1GTX
Member

Posts: 459




Ignore
« Reply #1 on: February 09, 2012, 03:52:44 PM »

Most of these coils resonate at a few mhz ao how far will they transmint and how wide is the bandwith.
Logged
KE3WD
Member

Posts: 5694




Ignore
« Reply #2 on: February 10, 2012, 06:05:27 AM »

About the vid, modulating arc plasma with audio to make soundwaves in the air. 

Lightning is what we call plasma excitation when the inert gas is predominantly nitrogen. 



Logged
KB1GTX
Member

Posts: 459




Ignore
« Reply #3 on: February 10, 2012, 12:37:07 PM »

I just built one using a car ionizer and the output section of a cb tapping the audio tranformer and it tears up the whole rf spectrom, even two meters fm is s9+ at 30 feet.
Logged
KE3WD
Member

Posts: 5694




Ignore
« Reply #4 on: February 10, 2012, 01:45:10 PM »

I'd consider 30 feet to be in the nearfield.  Seen flatscreen TVs that could do the same thing...
Logged
KB1GTX
Member

Posts: 459




Ignore
« Reply #5 on: February 10, 2012, 02:40:04 PM »

Yes , some plasma screens were bad, but this is really wide.
Logged
KE3WD
Member

Posts: 5694




Ignore
« Reply #6 on: February 10, 2012, 06:18:49 PM »

Resonant "Tesla coil" operation can be rather wide and contains plenty harmonics, but sans an antenna, propagation is not likely to travel too far. 

Which is basically why spark gap transmitters aren't legal on the bands...

Logged
W6RMK
Member

Posts: 648




Ignore
« Reply #7 on: February 12, 2012, 08:10:38 AM »

Most Tesla Coils (esp big ones) are in the 100 kHz range.
And these aren't spark gap transmitters.  They are basically a solid state power oscillator (usually using big IGBTs) driving an RF transformer, and actually have fairly well controlled RF spectrum. (google for DRSSTC)

However, given that they are operating in the 3km band, the "antenna" is pretty small and inefficient.

I've done quite a lot of analysis and tests on this kind of thing and the dominant RFI from them is actually not from the fundamental, but is the transients from the spark.  An individual spark is discharging  the capacitance of the top terminal (some 10s of pF, at a few hundred kV) over a loop that's several meters in cross section.  That is a pretty decent di/dt and generates a very nice waveform to kill victim equipment that's in the area.
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!