View Single Post
  #5   Report Post  
Old May 28th 07, 06:40 AM posted to rec.radio.amateur.antenna
John Smith I John Smith I is offline
external usenet poster
 
First recorded activity by RadioBanter: Dec 2006
Posts: 1,154
Default Confused over coax and windom - newbie

Andre C wrote:
I am very new at ham radio and find myself confused over an installation of a Carolina windom 80 special.

I attatched a 20m run of coax to the line isolator. When I switch on the rig I get nothing, even on strong BC stations. I assumed it was a coax prob and striped my plugs down etc. I then discovered that if the shielding was not touching the socket on the rig I got a very good signal. So I assumed there was a short in the coax. I checked the plugs and they seem fine but I note that even when I have just the co-ax plugged in (ie no windom) I get a good signal unless the shielding is connected. (I guess that would make sense though I thought the shielding stopped the centre core picking up a signal.

So where is my problem? Is it the antenna? Is it the ine isolator. (There is no indicator which way round it goes so I presume it is universal.) I have no tset equipment as yet so an easy solution would be valuable.


--------------= Posted using GrabIt =----------------
------= Binary Usenet downloading made easy =---------
-= Get GrabIt for free from http://www.shemes.com/ =-


OK. Let's apply logic here ...

1) If you have used a VOM and there is continuity between the center
conductor of one end of the coax, with the center conductor of the
opposite end of the coax, the center conductor is ok.


2) If you have continuity between the outer conductor of one end of the
coax (shield) with the outer conductor of the opposite end of the coax
(shield), the outer shield of the coax is ok.

3) If there is NO continuity between the center conductor of the coax
and the outer conductor of the coax, the coax has checked out completely.

Without knowing the construction details of the "line isolator"
(probably a ~6:1 balun or rf transformer of some sort) it is impossible
to know whether a short in this unit is normal (ok) or not. However, if
the center conductor of the coax connector on the "line isolator" shows
continuity with at least one leg of the windom, it shows there is
continuity through the "line isolator" from the coax center conductor to
the antenna proper. And, if there is continuity to at least one leg of
the windom to the outer conductor of the coax connector on the coax
connector on the "line isolator", it demonstrates there is continuity
from the outer conductor of the coax to the antenna proper.

At this point, I would assume the "line isolator" to be defective in
some unknown way (most likely improper hookup at the factory, solder
short, open winding, etc.)

I am afraid that is the best I can come up with.

I am taking it for granted the antenna is the "Carolina Windom 80
Special" made by Radio Works and is 66 feet long (well, short
actually!) 80 - 10 meters and can be found on this page:
http://radioworks.com/ccwcover.html

Warmest regards,
JS