Hi All,
There is an accessibility review and audio demo of the MFJ 1026 noise
cancellation unit at:
http://active-elements.org/2013/01/04/mfj-1026/
I would gladly add any other audio samples to the page.
Best wishes, Kelvin Marsh - M0AID
Working to improve accessibility for radio amateurs with disabilities
www.active-elements.org
For accessibility evaluations of amateur equipment and MP3 manuals
-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of eric oyen
Sent: 02 February 2014 22:25
To: [log in to unmask]
Subject: Re: Low Pass Filter
it makes a fairly large difference. I may have to make an audio =
recording and upload it here (or put it on audio boo). The only downside =
issue is that I cannot phase out more than one noise source, so I choose =
the strongest one and let the chips fall where they may on the rest.
-eric
On Feb 2, 2014, at 12:15 PM, richard fiorello wrote:
> Hi;
> Just wondering how high your noise level is before the mfj unit=20
> and how much of a difference it makes? I have turned off the=20
> things I suspect would be a problem and it makes no difference. =20
> Without the preamp the noise is s 5 with the receive preamp on it=20
> gets far worse. Its just not pleasant to listen to unless=20
> someone is s 9. Thought a larger external speaker would help but=20
> no success. richard
> sent from my braille note
>=20
> ----- Original Message -----
> From: eric oyen <[log in to unmask]
> To: [log in to unmask]
> Date sent: Sat, 1 Feb 2014 18:05:35 -0700
> Subject: Re: Low Pass Filter
>=20
> well,
> the situation here is a bit close. I have 12.6 Kv lines directly=20
> behind =3D
> the hose. THe neighbors have outdoor florescent lights (and=20
> there are =3D
> even 2 bug zappers). I have checked and there are at least 14=20
> wi-Fi =3D
> access points within 400 feet of me. THe house itself has 2 AP=20
> devices, =3D
> about 300 feet of LAN cable, 2 switches and 6 computer systems=20
> (the room =3D
> mates have 3 desktop systems). I have 3 laptop machines, 2 of=20
> which are =3D
> turned off. Half the lights in here are of the tube variety=20
> (those =3D
> stupid cheap made "green lamps"). all of these make some noise. =20
> As a =3D
> result, I also have to have an MFJ 2500 series antenna noise =3D
> cancellation unit in operation here just to remove all the=20
> electrical =3D
> noise. THe power lines are the worst of it.
>=20
> Basically, I am using every trick I can find to reduce or=20
> eliminate =3D
> noise before it hits my radio.
>=20
> -eric
>=20
> On Feb 1, 2014, at 5:49 PM, John Miller wrote:
>=20
> I actually never have lived in a place with a lot of noise. =20
> It's =3D
> funny,=3D20
> when I first was a ham, I was living with my parents, in the=20
> woods =3D
> pretty=3D20
> much with over a hundred feet between houses, well over 100 feet=20
> and =3D
> all=3D20
> woods behind me. Next place, in a neighboring town I was in an=20
> =3D
> apartment in=3D20
> the center of town, surrounded in a factory, houses, other=20
> businesses, =3D
> a=3D20
> place that converts vans to wheel chair vans and works on them,=20
> still =3D
> never=3D20
> had any noise for what ever reason and there you could about=20
> reach out =3D
> and=3D20
> touch the neighbors. Now I'm in a trailer park and we're not=20
> much =3D
> further=3D20
> away form each other I have a light off and on buzz here that my=20
> noise=3D20=3D
>=20
> blanker takes out and other than that, again very quiet. 2=20
> meters I =3D
> have=3D20
> noise but I couldn't care less about that and even that is rare. =20
> I =3D
> don't=3D20
> know why I'm that lucky. I spent 2 months with my in-laws at=20
> one =3D
> point,=3D20
> there, I had a +40 noise level from 160 through 70 CM, I could=20
> get on =3D
> GMRS,=3D20
> and 900 MHz from there, that was about it and no filtering=20
> remotely =3D
> helped=3D20
> that but that was an area with all businesses and apartments=20
> above =3D
> them once=3D20
> in a while.
> ----- Original Message -----=3D20
> From: "eric oyen" <[log in to unmask]
> To: <[log in to unmask]
> Sent: Saturday, February 01, 2014 7:00 PM
> Subject: Re: Low Pass Filter
> =3D20
> =3D20
> the funny thing is that low pass filters operate=20
> bi-directionally. If =3D
> =3D3D
> your radio produces harmonics that interfere above its normal =3D
> operating =3D3D
> range, then mix down products from sources above HF would also=20
> cause =3D
> =3D3D
> interference on HF. THese mix down products are often caused by=20
> =3D3D
> interactions within the first stage of the IF in your radio. =20
> SO, =3D
> using a =3D3D
> filter eliminates a lot of that from getting to your radio (thus=20
> =3D3D
> reducing or eliminating the problem).
> =3D20
> I have an FM radio station transmitter site less than 3 miles=20
> from me =3D
> =3D3D
> producing several thousand watts. without the filter, I hear=20
> what =3D
> sounds =3D3D
> like FM modulated signals in a couple of bands. I put the=20
> filter in =3D3D=3D
>=20
> place, and those signals disappeared. THere are other sources=20
> (such =3D
> as a =3D3D
> wireless Access point, LAN switches and cable modems'DSL modems=20
> that =3D
> =3D3D
> produce signals that can show up in HF directly. Filtering=20
> these is a =3D
> =3D3D
> bit harder. I am having to use ferrite beads on the power leads=20
> and =3D
> also =3D3D
> on the LAN cables to try and minimize some of these issues. I=20
> have =3D
> only =3D3D
> been partially successful. I still get a lot of birdies in the=20
> 10 =3D
> meter =3D3D
> band (around 28.5). I am going to acquire a portable shortwave=20
> =3D
> receiver =3D3D
> and try to track these signals to their source and see what I=20
> can do =3D
> to =3D3D
> remove them.
> =3D20
> -eric
> =3D20
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