Re: [IRCA] Common-Mode Choke Designed for MW DXing

[Robert LaFore <rdlafore@xxxxxxxxx>]

Chuck: These are in line. Nothing special. One antenna is a random wire 
of about 300 ft, in fairly close proximity to  a 'space loop' stung up 
in several trees. The chokes are in the shack, fed from the antennas and 
then using short jumpers as needed to get to the SDR-IQ and the Grundig.

Since the antennas are fairly close to each other there is a fair amount 
of interaction between the two. I had stopped using the SDR because of 
the broad noise it would throw off. That is gone now, along with a large 
amount of noise from my own house and a neighbor's house.

A good example, is WMAC-940 in Macon, roughly 100 miles south. It was 
just barely audible because of noise, despite a S7-S8 signal. With the 
chokes, its an easy signal to hear now.

At present I do not have the ability to sink a good ground here. But 
that is one project that will take place during the "off season" 
(summer). That may offer further improvements.


On 6/7/2016 8:28 PM, Chuck Hutton wrote:
> Robert:
>
> Did you just insert your new chokes in-line with the coax? Do you have any shield ground between the antenna  and the choke?
>
> Curious Chuck
>
> ________________________________________
> From: IRCA <irca-bounces@xxxxxxxxxxxxxxxx> on behalf of Robert LaFore <rdlafore@xxxxxxxxx>
> Sent: Tuesday, June 7, 2016 11:25 PM
> To: irca@xxxxxxxxxxxxxxxx
> Subject: Re: [IRCA] Common-Mode Choke Designed for MW DXing
>
> I just bought a pair of these to reduce some radiation from one antenna
> (using an SDR--Radiating Computer generated RF) into another antenna
> using a conventional receiver. I put one on each antenna, in the "shack".
>
> These common mode chokes have worked wonders, not only did they
> completely eliminate the PC/SDR noise, but they also reduce other
> induced noise from the house and neighbors.
>
> At least in my case---I am very satisfied!
>
>
>
> Robert LaFore
>
> Acworth GA
>
> On 4/27/2016 11:25 AM, Les Rayburn wrote:
> > In response to several requests from both MW DX’ers and 160 Meter enthusiasts, MyAntenna.com has added a new receive-only common-mode choke to their line of impressive products. This common mode choke can be inserted anywhere in the feed line to your BOG, active whip, loop, etc. The choke blocks unwanted noise that is often picked up by the coax as it travels from the antenna back to your shack.
> >
> > Many manufacturers claim that their chokes will work over impossible bandwidth of frequencies, which simply isn’t possible. In contrast, these chokes are designed to work over a limited range of frequencies. In this case it’s 500 KHz to 10 MHz.
> >
> > Common-mode attenuation: ~37dB
> > Choking Impedance >5,000 Ohms
> >
> > The choke will allow DC power to pass through to active antennas, and can be inserted anywhere in the feed line, including inside the shack. For best results, it’s recommended that the choke be installed about 20 feet from the antenna. I have no financial relationship with the company, but am a satisfied customer.
> >
> >
> >
> > http://myantennas.com/wp/product/cmc-0510-r/
> >
> > If you have EMI/RFI problems or just want to reduce the noise floor to your receiver, you can’t go wrong by installing good quality common-mode chokes in your system.
> >
> >
> > 73,
> >
> > Les Rayburn, N1LF
> > 121 Mayfair Park
> > Maylene, AL
> > EM63nf
> >
> > Member WTFDA, IRCA, NRC. Former CPC Chairman for NRC & IRCA.
> >
> > Elad FDM-S2 SDR, AirSpy SDR, Quantum Phaser, Wellbrook ALA1530 Loop, Wellbrook Flag, Clifton Labs Active Whip.
> >
> >
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> Be sure to register now for the Joint DX Convention
> Kansas City, September 9 to 11.  Hotel space is filling up.
> Registration info:
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>
> Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers
>
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Be sure to register now for the Joint DX Convention
Kansas City, September 9 to 11.  Hotel space is filling up.
Registration info:
http://www.nrcdxas.org


Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers

For more information: http://www.ircaonline.org

To Post a message: irca@xxxxxxxxxxxxxxxx