View Single Post
  #10   Report Post  
Old September 3rd 07, 05:09 AM posted to rec.radio.amateur.antenna
Owen Duffy Owen Duffy is offline
external usenet poster
 
First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Default making a common mode filter

Richard Clark wrote in
:

On 03 Sep 2007 03:26:50 GMT, Ed G
wrote:

loop fed by an SG-237 tuner. I wanted the choke for the coax feeding
the tuner.


Hi Ed,

You will have to choke the control lines just as much.

I do have RF causing
various issues inside the coach while I am transmitting.


That could be as easily through the air, or "ground currents" in the
chassis. All points of the chassis, doors, hood, etc. are not usually
bonded very well. Even the exhaust system can be "floating" to
provide a path from ground, right up into the engine compartment.

On your RV grounding question, yes, the antenna feedpoint and
all
related ground areas are very well bonded to the main vehicle chassis
with rather large tinned braid, (2" wide).


Re my paragraph above, does this include doors? A lot may be taken
for granted and hinged points are sometimes insulated, allowing large
panels (capacitive plates) to couple RF inside what is considered to
be an otherwise tight box.


Richard, getting clear details is like drawing teeth. I suspect the RV
might be fibreglass, and so about as RF transparent as you might get.
Further, something hints to me that the grounded ATU is on top of the
ladder, so it isn't really grounded.

But in the absense of clear details of a single scenario, I can't help.

Owen