16-07-2017, 10:18 AM
Alan,
Hopefully Doug will allow cross posting of the following:
http://www.vklogger.com/forum/viewtopic....61&t=13683
This is the archive of the previous forum where your problem was dealt with in quite some detail.
Within that topic is a reference to another posting: viewtopic.php?f=31&t=13534&start=20#p60419
which outlines the importance of considering all possible paths that RFI can take.
One common problem seems to be where the operator is using a vertical antenna.
If you think about it, in a portable situation, obtaining a reliable RF earth is often difficult (rocks etc.) The earth lead from the generator actually becomes part of the radiating antenna.
So one has to somehow isolate the earth lead from the generator.
(Way 1) a decent earth stake at the generator (difficult)
(Way 2) suitable ferrite filtering in the earth lead as well as the active and neutral leads.
If you look at most powerline filters available commercially, they only filter the active and neutral leads and maintain an DC earth path through the metal case. It is only when you go to the more sophisticated power line filters that are often used in medical rated equipment, that you find the earth lead being filtered as well.
So the trick is to introduce ferrite filtering of the earth lead as well. From a safety point of view you still maintain a DC connection, but at the RF frequencies, the signal does not pass.
Ideally a decent earth stake at the generator as well will always assist the situation. Note that on may of the Inverter generators available, the 240 volts is developed between Active and Neutral, rather than between Active and Earth as in our domestic M.E.N.S. system.
Cheers
Peter VK3QI (FD contest station VK3ER/p)
Alan,
I should have added that just disconnecting the earth lead from the generator is a big NO NO.
Cheers
Peter VK3QI
Hopefully Doug will allow cross posting of the following:
http://www.vklogger.com/forum/viewtopic....61&t=13683
This is the archive of the previous forum where your problem was dealt with in quite some detail.
Within that topic is a reference to another posting: viewtopic.php?f=31&t=13534&start=20#p60419
which outlines the importance of considering all possible paths that RFI can take.
One common problem seems to be where the operator is using a vertical antenna.
If you think about it, in a portable situation, obtaining a reliable RF earth is often difficult (rocks etc.) The earth lead from the generator actually becomes part of the radiating antenna.
So one has to somehow isolate the earth lead from the generator.
(Way 1) a decent earth stake at the generator (difficult)
(Way 2) suitable ferrite filtering in the earth lead as well as the active and neutral leads.
If you look at most powerline filters available commercially, they only filter the active and neutral leads and maintain an DC earth path through the metal case. It is only when you go to the more sophisticated power line filters that are often used in medical rated equipment, that you find the earth lead being filtered as well.
So the trick is to introduce ferrite filtering of the earth lead as well. From a safety point of view you still maintain a DC connection, but at the RF frequencies, the signal does not pass.
Ideally a decent earth stake at the generator as well will always assist the situation. Note that on may of the Inverter generators available, the 240 volts is developed between Active and Neutral, rather than between Active and Earth as in our domestic M.E.N.S. system.
Cheers
Peter VK3QI (FD contest station VK3ER/p)
Alan,
I should have added that just disconnecting the earth lead from the generator is a big NO NO.
Cheers
Peter VK3QI