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)"

On Mon, 22 Nov 2010 14:22:33 -0500, Bob wrote:

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.

Noise is the ear of the be-hearer. Characterize your problem with
noise levels observed at what time of day and in which band. If the
noise is bothersome, it is worth starting a log just so that you don't
go chasing your tail when it is merely seasonal.

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.

Have you changed the source of power to your
WinRadio/Computer/what-ever? Use an extension cord to a power strip
that provides power to EVERY gizmo plugged into the computer
supporting your WinRadio. Plug the extension into every branch from
your breaker box.

Take note of the emphasis on EVERY! Any exception turns this exercise
into an useless endeavor. In the past when our Internet connection
went to a modem, the Telephone ground brought grief. Connections like
that can slip beneath the radar. EVERY means your antenna line too -
which is to mean it might pass through a grounded connection along the
way, and that is enough to scotch this deal.

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)

You can find the same thing for less. You can build it even cheaper.
Think it's worth a try ? Why ?

What's your time worth?

Thoughts on ?

Sink a ground rod at the far end of your transmission line where it
connects to the antenna. Connect the coax shield to that rod.
Remember to connect that rod to your service ground through a SEPARATE
wire. Using the coax shield to bring the far ground back to the shack
invites disaster.

73's
Richard Clark, KB7QHC

Bob wrote:
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 ?



See this: http://www.audiosystemsgroup.com/RFI-Ham.pdf for lots of
explanation about chokes, filtering, which mixes to use, where some
sources of interference come from, etc.