View Single Post
  #1   Report Post  
Old November 22nd 10, 07:22 PM posted to rec.radio.amateur.antenna
Bob[_27_] Bob[_27_] is offline
external usenet poster
 
First recorded activity by RadioBanter: Mar 2010
Posts: 61
Default Common Mode Choke ?

Hi,

Like I mentioned in a previous post, I have a WinRadio Excalibur SDR
being fed by a PAR EF-SWL antenna.

Would like to improve the S/N ratio a bit.

After the PAR Balun, I have the typical coax run to the house.

I will get some of those snap on ferrites, as suggested, and try them out.

I have tried unplugging just about all of my wall warts in the vicinity,
the LinkSys Router and the Comcast Modem.
Surprisingly, at least to me, no discernable changes.

I see WinRadio offers, for $50 (ugh), a Common Mode Choke to go on the
coax at its end, right where it joins the Excalibur module.
(see specs, below)

Think it's worth a try ? Why ?
Thoughts on ?

Thanks, and a Happy Thanksgiving to all of you folks,
Bob
------------------
"This device provides a means of reducing or eliminating common-mode
noise from an antenna feedline, resulting in a considerable increase of
the received signal quality. Common-mode noise is generated by
computers, lamp dimmers and other electric or electronic appliances.
Such noise can be a problem especially in the lower portions of HF
spectrum, where weak signals can be sometimes completely masked by
assorted buzzes and other unwanted noises.

The Common-Mode Choke can be also very useful to provide an alternative
earthing point for an active antenna, if the antenna itself cannot be
grounded due to its location, or its ground connection is inadequate.

The WiNRADiO WR-CMC-30 common-mode choke is inserted in the antenna
coaxial feedline close to the receiver, in order to "choke" off
common-mode noise currents and passing them to ground without affecting
the useful signals between the antenna and the receiver.

The common-mode choke will let through DC current, which is useful in
situations where an active antenna (for example the WiNRADiO AX-81S)"